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Parabolic reflector

A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave travelling along the axis into a spherical wave converging toward the focus. Conversely, a spherical wave generated by a point source placed in the focus is reflected into a plane wave propagating as a collimated beam along the axis.

Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light). Since the principles of reflection are reversible, parabolic reflectors can also be used to collimate radiation from an isotropic source into a parallel beam. In optics, parabolic mirrors are used to gather light in reflecting telescopes and solar furnaces, and project a beam of light in flashlights, searchlights, stage spotlights, and car headlights. In radio, parabolic antennas are used to radiate a narrow beam of radio waves for point-to-point communications in satellite dishes and microwave relay stations, and to locate aircraft, ships, and vehicles in radar sets. In acoustics, parabolic microphones are used to record faraway sounds such as bird calls, in sports reporting, and to eavesdrop on private conversations in espionage and law enforcement.

Theory
Strictly, the three-dimensional shape of the reflector is called a paraboloid. A parabola is the two-dimensional figure. (The distinction is like that between a sphere and a circle.) However, in informal language, the word parabola and its associated adjective parabolic are often used in place of paraboloid and paraboloidal.

If a parabola is positioned in Cartesian coordinates with its vertex at the origin and its axis of symmetry along the y-axis, so the parabola opens upward, its equation is $4fy = x^2$, where $ f$ is its focal length. (See "Parabola".) Correspondingly, the dimensions of a symmetrical paraboloidal dish are related by the equation: $ 4FD = R^2$, where $ F$ is the focal length, $ D$  is the depth of the dish (measured along the axis of symmetry from the vertex to the plane of the rim), and $ R$  is the radius of the dish from the center. All units used for the radius, focal point and depth must be the same. If two of these three quantities are known, this equation can be used to calculate the third.

A more complex calculation is needed to find the diameter of the dish measured along its surface. This is sometimes called the "linear diameter", and equals the diameter of a flat, circular sheet of material, usually metal, which is the right size to be cut and bent to make the dish. Two intermediate results are useful in the calculation: $ P = 2F$ (or the equivalent: $ P = \frac{R^2}{2D}$ ) and $ Q = \sqrt {P^2+R^2}$, where $F$, $D$, and $R$ are defined as above. The diameter of the dish, measured along the surface, is then given by: $ \frac {RQ} {P} + P \ln \left ( \frac {R+Q} {P} \right )$, where $\ln(x)$ means the natural logarithm of $x$, i.e. its logarithm to base "e".

The volume of the dish is given by $\frac {1} {2} \pi R^2 D ,$ where the symbols are defined as above. This can be compared with the formulae for the volumes of a cylinder $(\pi R^2 D),$ a hemisphere $ (\frac {2}{3} \pi R^2 D,$  where $ D=R),$  and a cone $ ( \frac {1} {3} \pi R^2 D ).$   $ \pi R^2 $  is the aperture area of the dish, the area enclosed by the rim, which is proportional to the amount of sunlight the reflector dish can intercept. The area of the concave surface of the dish can be found using the area formula for a surface of revolution which gives $A=\frac{\pi R}{6 D^2}\left((R^2+4D^2)^{3/2}-R^3\right)$. providing $ D \ne 0$. The fraction of light reflected by the dish, from a light source in the focus, is given by $ 1 - \frac{\arctan\frac{R}{D-F}}{\pi}$, where $$F,$$ $$D,$$ and $$R$$ are defined as above.

The parabolic reflector functions due to the geometric properties of the paraboloidal shape: any incoming ray that is parallel to the axis of the dish will be reflected to a central point, or "focus". (For a geometrical proof, click here.) Because many types of energy can be reflected in this way, parabolic reflectors can be used to collect and concentrate energy entering the reflector at a particular angle. Similarly, energy radiating from the focus to the dish can be transmitted outward in a beam that is parallel to the axis of the dish.

In contrast with spherical reflectors, which suffer from a spherical aberration that becomes stronger as the ratio of the beam diameter to the focal distance becomes larger, parabolic reflectors can be made to accommodate beams of any width. However, if the incoming beam makes a non-zero angle with the axis (or if the emitting point source is not placed in the focus), parabolic reflectors suffer from an aberration called coma. This is primarily of interest in telescopes because most other applications do not require sharp resolution off the axis of the parabola.

The precision to which a parabolic dish must be made in order to focus energy well depends on the wavelength of the energy. If the dish is wrong by a quarter of a wavelength, then the reflected energy will be wrong by a half wavelength, which means that it will interfere destructively with energy that has been reflected properly from another part of the dish. To prevent this, the dish must be made correctly to within about $1⁄20$ of a wavelength. The wavelength range of visible light is between about 400 and 700 nanometres (nm), so in order to focus all visible light well, a reflector must be correct to within about 20 nm. For comparison, the diameter of a human hair is usually about 50,000 nm, so the required accuracy for a reflector to focus visible light is about 2500 times less than the diameter of a hair. For example, the flaw in the Hubble Space Telescope mirror (too flat by about 2,200 nm at its perimeter) caused severe spherical aberration until corrected with COSTAR.

Microwaves, such as are used for satellite-TV signals, have wavelengths of the order of ten millimetres, so dishes to focus these waves can be wrong by half a millimetre or so and still perform well.

Focus-balanced reflector

It is sometimes useful if the centre of mass of a reflector dish coincides with its focus. This allows it to be easily turned so it can be aimed at a moving source of light, such as the Sun in the sky, while its focus, where the target is located, is stationary. The dish is rotated around axes that pass through the focus and around which it is balanced. If the dish is symmetrical and made of uniform material of constant thickness, and if F represents the focal length of the paraboloid, this "focus-balanced" condition occurs if the depth of the dish, measured along the axis of the paraboloid from the vertex to the plane of the rim of the dish, is 1.8478 times F. The radius of the rim is 2.7187 F. The angular radius of the rim as seen from the focal point is 72.68 degrees.

Scheffler reflector
The focus-balanced configuration (see above) requires the depth of the reflector dish to be greater than its focal length, so the focus is within the dish. This can lead to the focus being difficult to access. An alternative approach is exemplified by the Scheffler reflector, named after its inventor, Wolfgang Scheffler. This is a paraboloidal mirror which is rotated about axes that pass through its centre of mass, but this does not coincide with the focus, which is outside the dish. If the reflector were a rigid paraboloid, the focus would move as the dish turns. To avoid this, the reflector is flexible, and is bent as it rotates so as to keep the focus stationary. Ideally, the reflector would be exactly paraboloidal at all times. In practice, this cannot be achieved exactly, so the Scheffler reflector is not suitable for purposes that require high accuracy. It is used in applications such as solar cooking, where sunlight has to be focused well enough to strike a cooking pot, but not to an exact point.

Off-axis reflectors

A circular paraboloid is theoretically unlimited in size. Any practical reflector uses just a segment of it. Often, the segment includes the vertex of the paraboloid, where its curvature is greatest, and where the axis of symmetry intersects the paraboloid. However, if the reflector is used to focus incoming energy onto a receiver, the shadow of the receiver falls onto the vertex of the paraboloid, which is part of the reflector, so part of the reflector is wasted. This can be avoided by making the reflector from a segment of the paraboloid which is offset from the vertex and the axis of symmetry. The whole reflector receives energy, which is then focused onto the receiver. This is frequently done, for example, in satellite-TV receiving dishes, and also in some types of astronomical telescope (e.g., the Green Bank Telescope, the James Webb Space Telescope).

Accurate off-axis reflectors, for use in solar furnaces and other non-critical applications, can be made quite simply by using a rotating furnace, in which the container of molten glass is offset from the axis of rotation. To make less accurate ones, suitable as satellite dishes, the shape is designed by a computer, then multiple dishes are stamped out of sheet metal.

Off-axis-reflectors heading from medium latitudes to a geostationary TV satellite somewhere above the equator stand steeper than a coaxial reflector. The effect is, that the arm to hold the dish can be shorter and snow tends less to accumulate in (the lower part of) the dish.

History
The principle of parabolic reflectors has been known since classical antiquity, when the mathematician Diocles described them in his book On Burning Mirrors and proved that they focus a parallel beam to a point. Archimedes in the third century BCE studied paraboloids as part of his study of hydrostatic equilibrium, and it has been claimed that he used reflectors to set the Roman fleet alight during the Siege of Syracuse. This seems unlikely to be true, however, as the claim does not appear in sources before the 2nd century CE, and Diocles does not mention it in his book. Parabolic mirrors and reflectors were also studied extensively by the physicist Roger Bacon in the 13th century AD. James Gregory, in his 1663 book Optica Promota (1663), pointed out that a reflecting telescope with a mirror that was parabolic would correct spherical aberration as well as the chromatic aberration seen in refracting telescopes. The design he came up with bears his name: the "Gregorian telescope"; but according to his own confession, Gregory had no practical skill and he could find no optician capable of actually constructing one. Isaac Newton knew about the properties of parabolic mirrors but chose a spherical shape for his Newtonian telescope mirror to simplify construction. Lighthouses also commonly used parabolic mirrors to collimate a point of light from a lantern into a beam, before being replaced by more efficient Fresnel lenses in the 19th century. In 1888, Heinrich Hertz, a German physicist, constructed the world's first parabolic reflector antenna.

Applications

The most common modern applications of the parabolic reflector are in satellite dishes, reflecting telescopes, radio telescopes, parabolic microphones, solar cookers, and many lighting devices such as spotlights, car headlights, PAR lamps and LED housings.

The Olympic Flame is traditionally lit at Olympia, Greece, using a parabolic reflector concentrating sunlight, and is then transported to the venue of the Games. Parabolic mirrors are one of many shapes for a burning glass.

Parabolic reflectors are popular for use in creating optical illusions. These consist of two opposing parabolic mirrors, with an opening in the center of the top mirror. When an object is placed on the bottom mirror, the mirrors create a real image, which is a virtually identical copy of the original that appears in the opening. The quality of the image is dependent upon the precision of the optics. Some such illusions are manufactured to tolerances of millionths of an inch.

A parabolic reflector pointing upward can be formed by rotating a reflective liquid, like mercury, around a vertical axis. This makes the liquid-mirror telescope possible. The same technique is used in rotating furnaces to make solid reflectors.

Parabolic reflectors are also a popular alternative for increasing wireless signal strength. Even with simple ones, users have reported 3 dB or more gains.

title: Parabolic reflector


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Castlereagh (borough)

Castlereagh was a local government district with the status of borough in Northern Ireland. It merged with Lisburn City Council in May 2015 under local government reorganisation in Northern Ireland to become Lisburn and Castlereagh City Council, with a small amount being transferred to Belfast City Council.

It was a mainly urban borough consisting mostly of suburbs of Belfast in the Castlereagh Hills (to the south-east of the city) with a small rural area in the south of the borough. Unusually, it had no natural borough centre. The main centres of population are Carryduff, 6 miles (9.6 km) south of Belfast city centre and Dundonald, 5 miles (8 km) east of it.

Castlereagh was named after the barony of Castlereagh, which in turn was named after the townland of same name (from the Irish An Caislean Riabhach, or Grey Castle, a reference to a stronghold of the Clandeboye O'Neils which stood on a site near what is now an Orange hall on Church Road).

Creation
The district was one of twenty-six created on 1 October 1973. It was formed by the amalgamation of the following areas of County Down: most of Castlereagh Rural District, the Carryduff and Newtownbreda areas of Hillsborough Rural District and the Moneyreagh area of North Down Rural District.

Borough council
The borough was divided into four electoral areas: Castlereagh Central, South, East and West. In the 2011 elections, 23 members were elected. As of February 2012 the political composition of the council was: 11 Democratic Unionist Party (DUP), 6 Alliance Party, 3 Ulster Unionist Party (UUP), 2 Social Democratic and Labour Party (SDLP) and 1 Green Party councillor. The last election was due to take place in May 2009, but on 25 April 2008, Shaun Woodward, Secretary of State for Northern Ireland announced that the scheduled 2009 district council elections were to be postponed until the introduction of the eleven new councils in 2011. The proposed reforms were abandoned in 2010, and the most recent district council elections took place in 2011

Mayor of Castlereagh
In 1977 Castlereagh District Council was granted a charter of incorporation constituting the district as a borough, and creating the office of mayor.

The mayor for the civic year 2013–2014 was councillor David Drysdale (DUP) and the Deputy Mayor was councillor Ann-Marie Beattie (DUP).

Parliamentary and assembly representation
The borough was divided between the East Belfast constituency (the wards of Ballyhanwood, Carrowreagh, Cregagh, Downshire, Dundonald, Enler, Gilnahirk, Graham's Bridge, Lisnasharragh, Lower Braniel, Tullycarnet and Upper Braniel), the South Belfast constituency (Beechill, Cairnshill, Carryduff East, Carryduff West, Galwally, Hillfoot, Knockbracken, Minnowburn, Newtownbreda and Wynchurch wards) and the Strangford constituency (Moneyreagh ward) for elections to the Westminster Parliament and Northern Ireland Assembly.

Elections 2011
These elections saw the political landscape at Castlereagh change dramatically. The DUP lost overall control of the council due to the loss of two council seats, one in Central and one in the East. The UUP also lost their sole representative in East. The Alliance Party gained one in East and Central, while the Green Party also gained in East. There were no changes in the West or South areas. There had been much speculation that demographic change would deliver Sinn Féin a seat in South. However, this turned out to be unfounded, with the SDLP being the sixth placed runner up, being narrowly beaten by the UUP for the fifth seat.

Population
The area covered by the former Castlereagh Borough Council had a population of 67,272 residents according to the 2011 Northern Ireland census.

Freedom of the Borough
The following people and military units have received the Freedom of the Borough of Castlereagh.

Individuals

 * George Best: 2002.
 * Peter Robinson: 2003.

Military Units

 * The Ulster Defence Regiment: 1984.
 * The Ulster Special Constabulary Association: 1992.
 * The Regimental Association of the Ulster Defence Regiment: 1994.
 * The Royal Irish Regiment: 1995.
 * The Royal British Legion: 1996.
 * The 204 (North Irish) Field Hospital Royal Army Medical Corps (Volunteers): 1998.
 * The Royal Ulster Constabulary GC: 2000.
 * The Northern Ireland Prison Service: 2004.
 * The 152 (North Irish) Regiment RLC (Volunteers): 25 May 2013.
 * The 152 Royal Electrical and Mechanical Engineers Workshops: 25 May 2013.
 * The Police Service of Northern Ireland: December 2014.

Further References
Bow, John. 2011. Castlereagh, Enlightenment War and Tyranny. Quercus. ISBN 978-0-85738-186-6

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Castlereagh (borough)


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Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a group of gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. It caused more than 100,000 deaths worldwide attributable to antimicrobial resistance in 2019.

MRSA is any strain of S. aureus that has developed (through natural selection) or acquired (through horizontal gene transfer) a multiple drug resistance to beta-lactam antibiotics. Beta-lactam (β-lactam) antibiotics are a broad-spectrum group that include some penams (penicillin derivatives such as methicillin and oxacillin) and cephems such as the cephalosporins. Strains unable to resist these antibiotics are classified as methicillin-susceptible S. aureus, or MSSA.

MRSA infection is common in hospitals, prisons, and nursing homes, where people with open wounds, invasive devices such as catheters, and weakened immune systems are at greater risk of healthcare-associated infection. MRSA began as a hospital-acquired infection but has become community-acquired, as well as livestock-acquired. The terms HA-MRSA (healthcare-associated or hospital-acquired MRSA), CA-MRSA (community-associated MRSA), and LA-MRSA (livestock-associated MRSA) reflect this.

Signs and symptoms

In humans, Staphylococcus aureus is part of the normal microbiota present in the upper respiratory tract, and on skin and in the gut mucosa. However, along with similar bacterial species that can colonize and act symbiotically, they can cause disease if they begin to take over the tissues they have colonized or invade other tissues; the resultant infection has been called a "pathobiont".

After 72 hours, MRSA can take hold in human tissues and eventually become resistant to treatment. The initial presentation of MRSA is small red bumps that resemble pimples, spider bites, or boils; they may be accompanied by fever and, occasionally, rashes. Within a few days, the bumps become larger and more painful; they eventually open into deep, pus-filled boils. About 75 percent of CA-MRSA infections are localized to skin and soft tissue and usually can be treated effectively.

Risk factors
A select few of the populations at risk include:
 * People with indwelling implants, prostheses, drains, and catheters
 * People who are frequently in crowded places, especially with shared equipment and skin-to-skin contact
 * People with weak immune systems (HIV/AIDS, lupus, or cancer patients; transplant recipients; severe asthmatics; etc.)
 * Diabetics
 * Intravenous drug users
 * Regular contact with someone who has injected drugs in the past year
 * Users of quinolone antibiotics
 * Elderly people
 * School children sharing sports and other equipment
 * College students living in dormitories
 * People staying or working in a health-care facility for an extended period of time
 * People who spend time in coastal waters where MRSA is present, such as some beaches in Florida and the West Coast of the United States
 * People who spend time in confined spaces with other people, including occupants of homeless shelters, prison inmates, and military recruits in basic training
 * Veterinarians, livestock handlers, and pet owners
 * People who ingest unpasteurized milk
 * People who are immunocompromised and also colonized
 * People with chronic obstructive pulmonary disease
 * People who have had thoracic surgery

As many as 22% of people infected with MRSA do not have any discernable risk factors.

Hospitalized people
People who are hospitalized, including the elderly, are often immunocompromised and susceptible to infection of all kinds, including MRSA; an infection by MRSA is called healthcare-associated or hospital-acquired methicillin-resistant S. aureus (HA-MRSA). Generally, those infected by MRSA stay infected for just under 10 days, if treated by a doctor, although effects may vary from person to person.

Both surgical and nonsurgical wounds can be infected with HA-MRSA. Surgical site infections occur on the skin surface, but can spread to internal organs and blood to cause sepsis. Transmission can occur between healthcare providers and patients because some providers may neglect to perform preventative hand-washing between examinations.

People in nursing homes are at risk for all the reasons above, further complicated by their generally weaker immune systems.

Prison inmates and military personnel
Prisons and military barracks can be crowded and confined, and poor hygiene conditions may proliferate, thus putting inhabitants at increased risk of contracting MRSA. Cases of MRSA in such populations were first reported in the United States and later in Canada. The earliest reports were made by the Centers for Disease Control and Prevention in US state prisons. In the news media, hundreds of reports of MRSA outbreaks in prisons appeared between 2000 and 2008. For example, in February 2008, the Tulsa County jail in Oklahoma started treating an average of 12 S. aureus cases per month.

Animals
Antibiotic use in livestock increases the risk that MRSA will develop among the livestock and other animals that may reside near them; strains MRSA ST398 and CC398 are transmissible to humans. Generally, animals are asymptomatic.

Domestic pets are susceptible to MRSA infection by transmission from their owners; conversely, MRSA-infected pets can also transmit MRSA to humans.

Athletes
Locker rooms, gyms, and related athletic facilities offer potential sites for MRSA contamination and infection. Athletes have been identified as a high-risk group. A study linked MRSA to the abrasions caused by artificial turf. Three studies by the Texas State Department of Health found the infection rate among football players was 16 times the national average. In October 2006, a high-school football player was temporarily paralyzed from MRSA-infected turf burns. His infection returned in January 2007 and required three surgeries to remove infected tissue, and three weeks of hospital stay.

In 2013, Lawrence Tynes, Carl Nicks, and Johnthan Banks of the Tampa Bay Buccaneers were diagnosed with MRSA. Tynes and Nicks apparently did not contract the infection from each other, but whether Banks contracted it from either individual is unknown. In 2015, Los Angeles Dodgers infielder Justin Turner was infected while the team visited the New York Mets. In October 2015, New York Giants tight end Daniel Fells was hospitalized with a serious MRSA infection.

Children
MRSA is becoming a critical problem in children; studies found 4.6% of patients in U.S. health-care facilities, (presumably) including hospital nurseries, were infected or colonized with MRSA. Children and adults who come in contact with day-care centers, playgrounds, locker rooms, camps, dormitories, classrooms and other school settings, and gyms and workout facilities are at higher risk of contracting MRSA. Parents should be especially cautious of children who participate in activities where sports equipment is shared, such as football helmets and uniforms.

Intravenous drug users
Needle-required drugs have caused an increase of MRSA, with injection drug use (IDU) making up 24.1% (1,839 individuals) of Tennessee Hospital's Discharge System. The unsanitary methods of injection causes an access point for the MRSA to enter the blood stream and begin infecting the host. Furthermore, with MRSA's high contagion rate, a common risk factor is individuals who are in constant contact with someone who has injected drugs in the past year.

Mechanism
Antimicrobial resistance is genetically based; resistance is mediated by the acquisition of extrachromosomal genetic elements containing genes that confer resistance to certain antibiotics. Examples of such elements include plasmids, transposable genetic elements, and genomic islands, which can be transferred between bacteria through horizontal gene transfer. A defining characteristic of MRSA is its ability to thrive in the presence of penicillin-like antibiotics, which normally prevent bacterial growth by inhibiting synthesis of cell wall material. This is due to a resistance gene, mecA, which stops β-lactam antibiotics from inactivating the enzymes (transpeptidases) critical for cell wall synthesis.

SCCmec
Staphylococcal cassette chromosome mec (SCCmec) is a genomic island of unknown origin containing the antibiotic resistance gene mecA. SCCmec contains additional genes beyond mecA, including the cytolysin gene psm-mec, which may suppress virulence in HA-acquired MRSA strains. In addition, this locus encodes strain-dependent gene regulatory RNAs known as psm-mecRNA. SCCmec also contains ccrA and ccrB; both genes encode recombinases that mediate the site-specific integration and excision of the SCCmec element from the S. aureus chromosome. Currently, six unique SCCmec types ranging in size from 21 to 67 kb have been identified; they are designated types I–VI and are distinguished by variation in mec and ccr gene complexes. Owing to the size of the SCCmec element and the constraints of horizontal gene transfer, a minimum of five clones are thought to be responsible for the spread of MRSA infections, with clonal complex (CC) 8 most prevalent. SCCmec is thought to have originated in the closely related Staphylococcus sciuri species and transferred horizontally to S. aureus.

Different SCCmec genotypes confer different microbiological characteristics, such as different antimicrobial resistance rates. Different genotypes are also associated with different types of infections. Types I–III SCCmec are large elements that typically contain additional resistance genes and are characteristically isolated from HA-MRSA strains. Conversely, CA-MRSA is associated with types IV and V, which are smaller and lack resistance genes other than mecA.

These distinctions were thoroughly investigated by Collins et al. in 2001, and can be explained by the fitness differences associated with carriage of a large or small SCCmec plasmid. Carriage of large plasmids, such as SCCmecI–III, is costly to the bacteria, resulting in a compensatory decrease in virulence expression. MRSA is able to thrive in hospital settings with increased antibiotic resistance but decreased virulence – HA-MRSA targets immunocompromised, hospitalized hosts, thus a decrease in virulence is not maladaptive. In contrast, CA-MRSA tends to carry lower-fitness cost SCCmec elements to offset the increased virulence and toxicity expression required to infect healthy hosts.

mecA
mecA is a biomarker gene responsible for resistance to methicillin and other β-lactam antibiotics. After acquisition of mecA, the gene must be integrated and localized in the S. aureus chromosome. mecA encodes penicillin-binding protein 2a (PBP2a), which differs from other penicillin-binding proteins as its active site does not bind methicillin or other β-lactam antibiotics. As such, PBP2a can continue to catalyze the transpeptidation reaction required for peptidoglycan cross-linking, enabling cell wall synthesis even in the presence of antibiotics. As a consequence of the inability of PBP2a to interact with β-lactam moieties, acquisition of mecA confers resistance to all β-lactam antibiotics in addition to methicillin.

mecA is under the control of two regulatory genes, mecI and mecR1. MecI is usually bound to the mecA promoter and functions as a repressor. In the presence of a β-lactam antibiotic, MecR1 initiates a signal transduction cascade that leads to transcriptional activation of mecA. This is achieved by MecR1-mediated cleavage of MecI, which alleviates MecI repression. mecA is further controlled by two co-repressors, blaI and blaR1. blaI and blaR1 are homologous to mecI and mecR1, respectively, and normally function as regulators of blaZ, which is responsible for penicillin resistance. The DNA sequences bound by mecI and blaI are identical; therefore, blaI can also bind the mecA operator to repress transcription of mecA.

Arginine catabolic mobile element
The arginine catabolic mobile element (ACME) is a virulence factor present in many MRSA strains but not prevalent in MSSA. SpeG-positive ACME compensates for the polyamine hypersensitivity of S. aureus and facilitates stable skin colonization, wound infection, and person-to-person transmission.

Strains
Acquisition of SCCmec in methicillin-sensitive S. aureus (MSSA) gives rise to a number of genetically different MRSA lineages. These genetic variations within different MRSA strains possibly explain the variability in virulence and associated MRSA infections. The first MRSA strain, ST250 MRSA-1, originated from SCCmec and ST250-MSSA integration. Historically, major MRSA clones ST2470-MRSA-I, ST239-MRSA-III, ST5-MRSA-II, and ST5-MRSA-IV were responsible for causing hospital-acquired MRSA (HA-MRSA) infections. ST239-MRSA-III, known as the Brazilian clone, was highly transmissible compared to others and distributed in Argentina, Czech Republic, and Portugal.

In the UK, the most common strains of MRSA are EMRSA15 and EMRSA16. EMRSA16 has been found to be identical to the ST36:USA200 strain, which circulates in the United States, and to carry the SCCmec type II, enterotoxin A and toxic shock syndrome toxin 1 genes. Under the new international typing system, this strain is now called MRSA252. EMRSA 15 is also found to be one of the common MRSA strains in Asia. Other common strains include ST5:USA100 and EMRSA 1. These strains are genetic characteristics of HA-MRSA.

Community-acquired MRSA (CA-MRSA) strains emerged in late 1990 to 2000, infecting healthy people who had not been in contact with healthcare facilities. Researchers suggest that CA-MRSA did not evolve from HA-MRSA. This is further proven by molecular typing of CA-MRSA strains and genome comparison between CA-MRSA and HA-MRSA, which indicate that novel MRSA strains integrated SCCmec into MSSA separately on its own. By mid-2000, CA-MRSA was introduced into healthcare systems and distinguishing CA-MRSA from HA-MRSA became a difficult process. Community-acquired MRSA is more easily treated and more virulent than hospital-acquired MRSA (HA-MRSA). The genetic mechanism for the enhanced virulence in CA-MRSA remains an active area of research. The Panton–Valentine leukocidin (PVL) genes are of particular interest because they are a unique feature of CA-MRSA.

In the United States, most cases of CA-MRSA are caused by a CC8 strain designated ST8:USA300, which carries SCCmec type IV, Panton–Valentine leukocidin, PSM-alpha and enterotoxins Q and K, and ST1:USA400. The ST8:USA300 strain results in skin infections, necrotizing fasciitis, and toxic shock syndrome, whereas the ST1:USA400 strain results in necrotizing pneumonia and pulmonary sepsis. Other community-acquired strains of MRSA are ST8:USA500 and ST59:USA1000. In many nations of the world, MRSA strains with different genetic background types have come to predominate among CA-MRSA strains; USA300 easily tops the list in the U.S. and is becoming more common in Canada after its first appearance there in 2004. For example, in Australia, ST93 strains are common, while in continental Europe ST80 strains, which carry SCCmec type IV, predominate. In Taiwan, ST59 strains, some of which are resistant to many non-beta-lactam antibiotics, have arisen as common causes of skin and soft tissue infections in the community. In a remote region of Alaska, unlike most of the continental U.S., USA300 was found only rarely in a study of MRSA strains from outbreaks in 1996 and 2000 as well as in surveillance from 2004 to 2006.

A MRSA strain, CC398, is found in intensively reared production animals (primarily pigs, but also cattle and poultry), where it can be transmitted to humans as LA-MRSA (livestock-associated MRSA).

Diagnosis
Diagnostic microbiology laboratories and reference laboratories are key for identifying outbreaks of MRSA. Normally, a bacterium must be cultured from blood, urine, sputum, or other body-fluid samples, and in sufficient quantities to perform confirmatory tests early-on. Still, because no quick and easy method exists to diagnose MRSA, initial treatment of the infection is often based upon "strong suspicion" and techniques by the treating physician; these include quantitative PCR procedures, which are employed in clinical laboratories for quickly detecting and identifying MRSA strains.

Another common laboratory test is a rapid latex agglutination test that detects the PBP2a protein. PBP2a is a variant penicillin-binding protein that imparts the ability of S. aureus to be resistant to oxacillin.

Microbiology
Like all S. aureus (also abbreviated SA at times), methicillin-resistant S. aureus is a gram-positive, spherical (coccus) bacterium about 1 micron in diameter. It does not form spores and it is not motile. It is frequently found in grape-like clusters or chains. Unlike methicillin-susceptible S. aureus (MSSA), MRSA is slow-growing on a variety of media and has been found to exist in mixed colonies of MSSA. The mecA gene, which confers resistance to a number of antibiotics, is always present in MRSA and usually absent in MSSA; however, in some instances, the mecA gene is present in MSSA but is not expressed. Polymerase chain reaction (PCR) testing is the most precise method for identifying MRSA strains. Specialized culture media have been developed to better differentiate between MSSA and MRSA and, in some cases, such media can be used to identify specific strains that are resistant to different antibiotics.

Other strains of S. aureus have emerged that are resistant to oxacillin, clindamycin, teicoplanin, and erythromycin. These resistant strains may or may not possess the mecA gene. S. aureus has also developed resistance to vancomycin (VRSA). One strain is only partially susceptible to vancomycin and is called vancomycin-intermediate S. aureus (VISA). GISA, a strain of resistant S. aureus, is glycopeptide-intermediate S. aureus and is less suspectible to vancomycin and teicoplanin. Resistance to antibiotics in S. aureus can be quantified by determining the amount of the antibiotic that must be used to inhibit growth. If S. aureus is inhibited at a concentration of vancomycin less than or equal to 4 μg/ml, it is said to be susceptible. If a concentration greater than 32 μg/ml is necessary to inhibit growth, it is said to be resistant.

Screening
In health-care settings, isolating those with MRSA from those without the infection is one method to prevent transmission. Rapid culture and sensitivity testing and molecular testing identifies carriers and reduces infection rates. It is especially important to test patients in these settings since 2% of people are carriers of MRSA, even though in many of these cases the bacteria reside in the nostril and the patient will not present any symptoms.

MRSA can be identified by swabbing the nostrils and isolating the bacteria found there. Combined with extra sanitary measures for those in contact with infected people, swab screening people admitted to hospitals has been found to be effective in minimizing the spread of MRSA in hospitals in the United States, Denmark, Finland, and the Netherlands.

Handwashing
The Centers for Disease Control and Prevention offers suggestions for preventing the contraction and spread of MRSA infection which are applicable to those in community settings, including incarcerated populations, childcare center employees, and athletes. To prevent the spread of MRSA, the recommendations are to wash hands thoroughly and regularly using soap and water or an alcohol-based sanitizer. Additional recommendations are to keep wounds clean and covered, avoid contact with other people's wounds, avoid sharing personal items such as razors or towels, shower after exercising at athletic facilities, and shower before using swimming pools or whirlpools.

Isolation
Excluding medical facilities, current US guidance does not require workers with MRSA infections to be routinely excluded from the general workplace. The National Institutes of Health recommend that those with wound drainage that cannot be covered and contained with a clean, dry bandage and those who cannot maintain good hygiene practices be reassigned, and patients with wound drainage should also automatically be put on "Contact Precaution," regardless of whether or not they have a known infection. Workers with active infections are excluded from activities where skin-to-skin contact is likely to occur. To prevent the spread of staphylococci or MRSA in the workplace, employers are encouraged to make available adequate facilities that support good hygiene. In addition, surface and equipment sanitizing should conform to Environmental Protection Agency-registered disinfectants. In hospital settings, contact isolation can be stopped after one to three cultures come back negative. Before the patient is cleared from isolation, it is advised that there is dedicated patient-care or single-use equipment for that particular patient. If this is not possible, the equipment must be properly disinfected before it is used on another patient.

To prevent the spread of MRSA in the home, health departments recommend laundering materials that have come into contact with infected persons separately and with a dilute bleach solution; to reduce the bacterial load in one's nose and skin; and to clean and disinfect those things in the house that people regularly touch, such as sinks, tubs, kitchen counters, cell phones, light switches, doorknobs, phones, toilets, and computer keyboards.

Restricting antibiotic use
Glycopeptides, cephalosporins, and in particular, quinolones are associated with an increased risk of colonisation of MRSA. Reducing use of antibiotic classes that promote MRSA colonisation, especially fluoroquinolones, is recommended in current guidelines.

Public health considerations
Mathematical models describe one way in which a loss of infection control can occur after measures for screening and isolation seem to be effective for years, as happened in the UK. In the "search and destroy" strategy that was employed by all UK hospitals until the mid-1990s, all hospitalized people with MRSA were immediately isolated, and all staff were screened for MRSA and were prevented from working until they had completed a course of eradication therapy that was proven to work. Loss of control occurs because colonised people are discharged back into the community and then readmitted; when the number of colonised people in the community reaches a certain threshold, the "search and destroy" strategy is overwhelmed. One of the few countries not to have been overwhelmed by MRSA is the Netherlands: an important part of the success of the Dutch strategy may have been to attempt eradication of carriage upon discharge from hospital.

Decolonization
As of 2013, no randomized clinical trials had been conducted to understand how to treat nonsurgical wounds that had been colonized, but not infected, with MRSA, and insufficient studies had been conducted to understand how to treat surgical wounds that had been colonized with MRSA. As of 2013, whether strategies to eradicate MRSA colonization of people in nursing homes reduced infection rates was not known.

Care should be taken when trying to drain boils, as disruption of surrounding tissue can lead to larger infections, including infection of the blood stream. Mupirocin 2% ointment can be effective at reducing the size of lesions. A secondary covering of clothing is preferred. As shown in an animal study with diabetic mice, the topical application of a mixture of sugar (70%) and 3% povidone-iodine paste is an effective agent for the treatment of diabetic ulcers with MRSA infection.

Community settings
Maintaining the necessary cleanliness may be difficult for people if they do not have access to facilities such as public toilets with handwashing facilities. In the United Kingdom, the Workplace (Health, Safety and Welfare) Regulations 1992 require businesses to provide toilets for their employees, along with washing facilities including soap or other suitable means of cleaning. Guidance on how many toilets to provide and what sort of washing facilities should be provided alongside them is given in the Workplace (Health, Safety and Welfare) Approved Code of Practice and Guidance L24, available from Health and Safety Executive Books, but no legal obligations exist on local authorities in the United Kingdom to provide public toilets, and although in 2008, the House of Commons Communities and Local Government Committee called for a duty on local authorities to develop a public toilet strategy, this was rejected by the Government.

Agriculture
The World Health Organization advocates regulations on the use of antibiotics in animal feed to prevent the emergence of drug-resistant strains of MRSA. MRSA is established in animals and birds.

Antibiotics
Treatment of MRSA infection is urgent and delays can be fatal. The location and history related to the infection determines the treatment. The route of administration of an antibiotic varies. Antibiotics effective against MRSA can be given by IV, oral, or a combination of both, and depend on the specific circumstances and patient characteristics. The use of concurrent treatment with vancomycin or other beta-lactam agents may have a synergistic effect.

Both CA-MRSA and HA-MRSA are resistant to traditional anti-staphylococcal beta-lactam antibiotics, such as cephalexin. CA-MRSA has a greater spectrum of antimicrobial susceptibility to sulfa drugs (like co-trimoxazole (trimethoprim/sulfamethoxazole), tetracyclines (like doxycycline and minocycline) and clindamycin (for osteomyelitis). MRSA can be eradicated with a regimen of linezolid, though treatment protocols vary and serum levels of antibiotics vary widely from person to person and may affect outcomes. The effective treatment of MRSA with linezolid has been successful in 87% of people. Linezolid is more effective in soft tissue infections than vancomycin. This is compared to eradication of infection in those with MRSA treated with vancomycin. Treatment with vancomycin is successful in approximately 49% of people. Linezolid belongs to the newer oxazolidinone class of antibiotics which has been shown to be effective against both CA-MRSA and HA-MRSA. The Infectious Disease Society of America recommends vancomycin, linezolid, or clindamycin (if susceptible) for treating those with MRSA pneumonia. Ceftaroline, a fifth-generation cephalosporin, is the first beta-lactam antibiotic approved in the US to treat MRSA infections in skin and soft tissue or community-acquired pneumonia.

Vancomycin and teicoplanin are glycopeptide antibiotics used to treat MRSA infections. Teicoplanin is a structural congener of vancomycin that has a similar activity spectrum but a longer half-life. Because the oral absorption of vancomycin and teicoplanin is very low, these agents can be administered intravenously to control systemic infections. Treatment of MRSA infection with vancomycin can be complicated, due to its inconvenient route of administration. Moreover, the efficacy of vancomycin against MRSA is inferior to that of anti-staphylococcal beta-lactam antibiotics against methicillin-susceptible S. aureus (MSSA).

Several newly discovered strains of MRSA show antibiotic resistance even to vancomycin and teicoplanin. Strains with intermediate (4–8 μg/ml) levels of resistance, termed glycopeptide-intermediate S. aureus (GISA) or vancomycin-intermediate S. aureus (VISA), began appearing in the late 1990s. The first identified case was in Japan in 1996, and strains have since been found in hospitals in England, France, and the US. The first documented strain with complete (>16 μg/ml) resistance to vancomycin, termed vancomycin-resistant S. aureus (VRSA), appeared in the United States in 2002. In 2011, a variant of vancomycin was tested that binds to the lactate variation and also binds well to the original target, thus reinstating potent antimicrobial activity. Linezolid, quinupristin/dalfopristin, daptomycin, ceftaroline, and tigecycline are used to treat more severe infections that do not respond to glycopeptides such as vancomycin. Current guidelines recommend daptomycin for VISA bloodstream infections and endocarditis.

Oxazolidinones such as linezolid became available in the 1990s and are comparable to vancomycin in effectiveness against MRSA. Linezolid resistance in S. aureus was reported in 2001, but infection rates have been at consistently low levels. In the United Kingdom and Ireland, no linezolid resistance was found in staphylococci collected from bacteremia cases between 2001 and 2006.

Skin and soft-tissue infections
In skin abscesses, the primary treatment recommended is removal of dead tissue, incision, and drainage. More information is needed to determine the effectiveness of specific antibiotics therapy in surgical site infections (SSIs). Examples of soft-tissue infections from MRSA include ulcers, impetigo, abscesses, and SSIs. In surgical wounds, evidence is weak (high risk of bias) that linezolid may be better than vancomycin to eradicate MRSA SSIs.

MRSA colonization is also found in nonsurgical wounds such as traumatic wounds, burns, and chronic ulcers (i.e.: diabetic ulcer, pressure ulcer, arterial insufficiency ulcer, venous ulcer). No conclusive evidence has been found about the best antibiotic regimen to treat MRSA colonization.

Children
In skin infections and secondary infection sites, topical mupirocin is used successfully. For bacteremia and endocarditis, vancomycin or daptomycin is considered. For children with MRSA-infected bone or joints, treatment is individualized and long-term. Neonates can develop neonatal pustulosis as a result of topical infection with MRSA. Clindamycin is not approved for the treatment of MRSA infection, but it is still used in children for soft-tissue infections.

Endocarditis and bacteremia
Evaluation for the replacement of a prosthetic valve is considered. Appropriate antibiotic therapy may be administered for up to six weeks. Four to six weeks of antibiotic treatment is often recommended, and is dependent upon the extent of MRSA infection.

Respiratory infections
CA-MRSA in hospitalized patients pneumonia treatment begins before culture results. After the susceptibility to antibiotics is performed, the infection may be treated with vancomycin or linezolid for up to 21 days. If the pneumonia is complicated by the accumulation of pus in the pleural cavity surrounding the lungs, drainage may be done along with antibiotic therapy. People with cystic fibrosis may develop respiratory complications related to MRSA infection. The incidence of MRSA in those with cystic fibrosis increased during 2000 to 2015 by five times. Most of these infections were HA-MRSA. MRSA accounts for 26% of lung infections in those with cystic fibrosis.

There is insufficient evidence to support the use of topical or systematic antibiotics for nasal or extra-nasal MRSA infection.

Bone and joint infections
Cleaning the wound of dead tissue and draining abscesses is the first action to treat the MRSA infection. Administration of antibiotics is not standardized and is adapted by a case-by-case basis. Antibiotic therapy can last up to 3 months and sometimes even longer.

Infected implants
MRSA infection can occur associated with implants and joint replacements. Recommendations on treatment are based upon the length of time the implant has been in place. In cases of a recent placement of a surgical implant or artificial joint, the device may be retained while antibiotic therapy continues. If the placement of the device has occurred over 3 weeks ago, the device may be removed. Antibiotic therapy is used in each instance sometimes long-term.

Central nervous system
MRSA can infect the central nervous system and form brain abscess, subdural empyema, and spinal epidural abscess. Excision and drainage can be done along with antibiotic treatment. Septic thrombosis of cavernous or dural venous sinus can sometimes be a complication.

Other infections
Treatment is not standardized for other instances of MRSA infection in a wide range of tissues. Treatment varies for MRSA infections related to: subperiosteal abscesses, necrotizing pneumonia, cellulitis, pyomyositis, necrotizing fasciitis, mediastinitis, myocardial, perinephric, hepatic, and splenic abscesses, septic thrombophlebitis, and severe ocular infections, including endophthalmitis. Pets can be reservoirs and pass on MRSA to people. In some cases, the infection can be symptomatic and the pet can develop a MRSA infection. Health departments recommend that the pet be taken to the veterinarian if MRSA infections keep occurring in the people who have contact with the pet.

Epidemiology
Worldwide, an estimated 2 billion people carry some form of S. aureus; of these, up to 53 million (2.7% of carriers) are thought to carry MRSA. S. aureus was identified as one of the six leading pathogens for deaths associated with resistance in 2019 and 100,000 deaths caused by MRSA were attributable to antimicrobial resistance.

HA-MRSA
In a US cohort study of 1,300 healthy children, 2.4% carried MRSA in their nose. Bacterial sepsis occurs with most (75%) of cases of invasive MRSA infection. In 2009, there were an estimated 463,017 hospitalizations due to MRSA, or a rate of 11.74 per 1,000 hospitalizations. Many of these infections are less serious, but the Centers for Disease Control and Prevention (CDC) estimate that there are 80,461 invasive MRSA infections and 11,285 deaths due to MRSA annually. In 2003, the cost for a hospitalization due to MRSA infection was US$92,363; a hospital stay for MSSA was $52,791.

Infection after surgery is relatively uncommon, but occurs as much as 33% in specific types of surgeries. Infections of surgical sites range from 1% to 33%. MRSA sepsis that occurs within 30 days following a surgical infection has a 15–38% mortality rate; MRSA sepsis that occurs within one year has a mortality rate of around 55%. There may be increased mortality associated with cardiac surgery. There is a rate of 12.9% in those infected with MRSA while only 3% infected with other organisms. SSIs infected with MRSA had longer hospital stays than those who did not.

Globally, MRSA infection rates are dynamic and vary year to year. According to the 2006 SENTRY Antimicrobial Surveillance Program report, the incidence of MRSA bloodstream infections was 35.9% in North America. MRSA blood infections in Latin America was 29%. European incidence was 22.8%. The rate of all MRSA infections in Europe ranged from 50% in Portugal down to 0.8% in Sweden. Overall MRSA infection rates varied in Latin America: Colombia and Venezuela combined had 3%, Mexico had 50%, Chile 38%, Brazil 29%, and Argentina 28%.

The Centers for Disease Control and Prevention (CDC) estimated that about 1.7 million nosocomial infections occurred in the United States in 2002, with 99,000 associated deaths. The estimated incidence is 4.5 nosocomial infections per 100 admissions, with direct costs (at 2004 prices) ranging from $10,500 (£5300, €8000 at 2006 rates) per case (for bloodstream, urinary tract, or respiratory infections in immunocompetent people) to $111,000 (£57,000, €85,000) per case for antibiotic-resistant infections in the bloodstream in people with transplants. With these numbers, conservative estimates of the total direct costs of nosocomial infections are above $17 billion. The reduction of such infections forms an important component of efforts to improve healthcare safety. (BMJ 2007) MRSA alone was associated with 8% of nosocomial infections reported to the CDC National Healthcare Safety Network from January 2006 to October 2007.

The British National Audit Office estimated that the incidence of nosocomial infections in Europe ranges from 4% to 10% of all hospital admissions. As of early 2005, the number of deaths in the United Kingdom attributed to MRSA has been estimated by various sources to lie in the area of 3,000 per year.

In the United States, an estimated 95 million people carry S. aureus in their noses; of these, 2.5 million (2.6% of carriers) carry MRSA. A population review conducted in three U.S. communities showed the annual incidence of CA-MRSA during 2001–2002 to be 18–25.7/100,000; most CA-MRSA isolates were associated with clinically relevant infections, and 23% of people required hospitalization.

CA-MRSA
In a US cohort study of 1,300 healthy children, 2.4% carried MRSA in their noses. There are concerns that the presence of MRSA in the environment may allow resistance to be transferred to other bacteria through phages (viruses that infect bacteria). The source of MRSA could come from hospital waste, farm sewage, or other waste water.

LA-MRSA
In 2004, MRSA was first isolated on a Dutch pig farm leading to further investigations of livestock associated MRSA (LA-MRSA). Livestock associated MRSA (LA-MRSA) has been observed in Korea, Brazil, Switzerland, Malaysia, India, Great Britain, Denmark, and China.

History
In 1961, the first known MRSA isolates were reported in a British study, and from 1961 to 1967, infrequent hospital outbreaks occurred in Western Europe and Australia, with methicillin then being licensed in England to treat resistant infections. Other reports of MRSA began to be described in the 1970s. Resistance to other antibiotics was documented in some strains of S. aureus. In 1996, vancomycin resistance was reported in Japan. In many countries, outbreaks of MRSA infection were reported to be transmitted between hospitals. The rate had increased to 22% by 1995, and by 1997 the level of hospital S. aureus infections attributable to MRSA had reached 50%.

The first report of community-associated MRSA (CA-MRSA) occurred in 1981, and in 1982, a large outbreak of CA-MRSA occurred among intravenous drug users in Detroit, Michigan. Additional outbreaks of CA-MRSA were reported through the 1980s and 1990s, including outbreaks among Australian Aboriginal populations that had never been exposed to hospitals. In the mid-1990s, scattered reports of CA-MRSA outbreaks among US children were made. While HA-MRSA rates stabilized between 1998 and 2008, CA-MRSA rates continued to rise. A report released by the University of Chicago Children's Hospital comparing two periods (1993–1995 and 1995–1997) found a 25-fold increase in the rate of hospitalizations due to MRSA among children in the United States. In 1999, the University of Chicago reported the first deaths from invasive MRSA among otherwise healthy children in the United States. By 2004, the genome for various strains of MRSA were described.

The observed increased mortality among MRSA-infected people arguably may be the result of the increased underlying morbidity of these people. Several studies, however, including one by Blot and colleagues, that have adjusted for underlying disease still found MRSA bacteremia to have a higher attributable mortality than methicillin-susceptible S. aureus (MSSA) bacteremia.

A population-based study of the incidence of MRSA infections in San Francisco during 2004–05 demonstrated that nearly one in 300 residents had such an infection in the course of a year and that greater than 85% of these infections occurred outside of the healthcare setting. A 2004 study showed that people in the United States with S. aureus infection had, on average, three times the length of hospital stay (14.3 vs. 4.5 days), incurred three times the total cost ($48,824 vs. $14,141), and experienced five times the risk of in-hospital death (11.2% vs 2.3%) than people without this infection. In a meta-analysis of 31 studies, Cosgrove et al., concluded that MRSA bacteremia is associated with increased mortality as compared with MSSA bacteremia (odds ratio= 1.93; 95% ). In addition, Wyllie et al. report a death rate of 34% within 30 days among people infected with MRSA, a rate similar to the death rate of 27% seen among MSSA-infected people.

In the US, the CDC issued guidelines on October 19, 2006, citing the need for additional research, but declined to recommend such screening. According to the CDC, the most recent estimates of the incidence of healthcare-associated infections that are attributable to MRSA in the United States indicate a decline in such infection rates. Incidence of MRSA central line-associated blood-stream infections as reported by hundreds of intensive care units decreased 50–70% from 2001 to 2007. A separate system tracking all hospital MRSA bloodstream infections found an overall 34% decrease between 2005 and 2008. In 2010, vancomycin was the drug of choice.

Across Europe, based mostly on data from 2013, seven countries (Iceland, Norway, Sweden, the Netherlands, Denmark, Finland, and Estonia, from lowest to highest) had low levels of hospital-acquired MRSA infections compared to the others, and among countries with higher levels, significant improvements had been made only in Bulgaria, Poland, and the British Isles.

A 1,000-year-old eye salve recipe found in the medieval Bald's Leechbook at the British Library, one of the earliest known medical textbooks, was found to have activity against MRSA in vitro and in skin wounds in mice.

In the media
MRSA is frequently a media topic, especially if well-known personalities have announced that they have or have had the infection. Word of outbreaks of infection appears regularly in newspapers and television news programs. A report on skin and soft-tissue infections in the Cook County jail in Chicago in 2004–05 demonstrated MRSA was the most common cause of these infections among those incarcerated there. Lawsuits filed against those who are accused of infecting others with MRSA are also popular stories in the media.

MRSA is the topic of radio programs, television shows,  books, and movies.

Research
Various antibacterial chemical extracts from various species of the sweetgum tree (genus Liquidambar) have been investigated for their activity in inhibiting MRSA. Specifically, these are: cinnamic acid, cinnamyl cinnamate, ethyl cinnamate, benzyl cinnamate, styrene, vanillin, cinnamyl alcohol, 2-phenylpropyl alcohol, and 3-phenylpropyl cinnamate.

The delivery of inhaled antibiotics along with systematic administration to treat MRSA are being developed. This may improve the outcomes of those with cystic fibrosis and other respiratory infections. Phage therapy has been used for years in MRSA in eastern countries, and studies are ongoing in western countries. Host-directed therapeutics, including host kinase inhibitors, as well as antimicrobial peptides are under study as adjunctive or alternative treatment for MRSA.

A 2015 Cochrane systematic review aimed to assess the effectiveness of wearing gloves, gowns and masks to help stop the spread of MRSA in hospitals, however no eligible studies were identified for inclusion. The review authors concluded that there is a need for randomized controlled trials to be conducted to help determine if the use of gloves, gowns, and masks reduces the transmission of MRSA in hospitals.


text:
Talk:Robert Stewart, Viscount Castlereagh

Comments 2003-2004
Stewart became the Marquess of Londonderry, but historically he is known as Lord Castlereagh. Using his highest title would give him an unrecognisable name. I have thus used his most commonly recognised title with his name. JtdIrL 19:49 Mar 6, 2003 (UTC)

 * I'm not sure that he ever succeeded to his father's title, did he? Deb 19:57 Mar 6, 2003 (UTC)

I'm not sure. I just followed what the article stated. JtdIrL 22:01 Mar 6, 2003 (UTC)

 * Yes, you're right, he was briefly Marquess. Some of the places I looked it up didn't mention it, and some had him down as being the son of the Second Marquess  -- possibly because of the earl/marquess change. Deb 17:57 Mar 7, 2003 (UTC)

 * Hm... slight problem, perhaps. His father was also briefly 'Robert Stewart, Viscount Castlereagh' until he was created an earl. Do we just ignore this?Mintguy 23:27, 16 Aug 2003 (UTC)

 * I'll add a disambig soon. But I have a question: the article mentions that someone told Castlereagh to "consult a physician", and he committed suicide thereafter. Did he commit suicide because he was paranoid and thought "consult a physician" meant something else? Or did he commit suicide because he was insane? I can't really find the reasoning in that in the article, or maybe I'm just not looking hard enough... ugen64 16:28, Sep 11, 2004 (UTC)

In terms of the disambiguation, I don't think it's terribly important - his father was only known as Viscount Castlereagh for a year, between 1795 and 1796, when he became Earl of Londonderry. As to the latter part, Castlereagh was being blackmailed for supposedly being a homosexual. The "consult a physician" bit does not seemed to have caused his suicide. it was just the king's response to this news, which was hardly encouraging for Castlereagh. john k 16:37, 11 Sep 2004 (UTC)

 * I added that final para. IIRC no-one has ever been sure whether there really was a blackmailer ot whether it was in Castlereagh's head. I think perhaps that King was intending suggest that Castlereagh needed to seek medical advice because he thought that the blackmail was in Castlereagh's mind. Or pehaps the words were intended to suggest the Castlereagh consult a physician to "cure him" of homosexual tendencies, or perhaps the King just wanted to get rid of him and the response satistfied either situation. I don't have a citation for the quotes, I have to admit I read it on the web somewhere. Mintguy (T) 18:14, 11 Sep 2004 (UTC)

Leader of the Commons in 1821-22?
How could he have held the post for the last year of his life when he was in the House of Lords? (Technically as the Lord Stewart.) Timrollpickering 16:16, 5 Dec 2004 (UTC)

 * My mistake - Lord Stewart was his half-brother, the 3rd Marquess, who was already enobled during Castlereagh's lifetime. Timrollpickering 01:39, 17 Dec 2004 (UTC)

Yup, yup. Old Charles Stewart was British ambassador to Prussia during the latter part of the Napoleonic Wars. john k 05:04, 17 Dec 2004 (UTC)

 * Lord Londonderry was able to remain Leader of the House of Commons because he was an Irish peer, not a British one.

 * To clarify in case the subject comes up again. The Marquess of Londonderry is in the Irish peerage. Castlereagh's father, the 1st Marquess, sat in the UK House of Lords because he was made a Representative Peer as part of the Act of Union. But the "representative" status was personal, not hereditary. So on his death, his seat in the House of Lords was taken by another Irish peer who was appointed as a "representative peer" to replace him. Given Castlereagh's political stature and record of service, he could have undoubtedly been appointed to replace his father as "representative peer" in the House of Lords. But he was rather desperately needed to continue to lead the Commons. Dunnettreader (talk) 05:36, 7 July 2009 (UTC)

Page Move
General consensus has been that he should remain at Viscount Castlereagh, as that is how he is best known. So I have moved him back. john k 01:50, 29 Jan 2005 (UTC)

The Most Honourable
Pray tell, why can't the article begin with his style? Thesocialistesq 04:39, 3 March 2006 (UTC)

-rah or -rey?
How would one pronounce "Castlereagh"?

 * "Caa-sul-ray". Proteus (Talk) 15:19, 16 March 2006 (UTC)
 * There is a Castlereagh Street in Sydney (Australia). I have heard the pronunciation "Castlerock" there. --82.135.90.142 (talk) 22:44, 2 November 2009 (UTC)

"ray," as evidenced by the rhymes in various poems by Byron and Shelley that incorporated the name (and biting criticism of the person). — Preceding unsigned comment added by 71.243.209.24 (talk) 20:36, 10 August 2012 (UTC)

GA quick-failed
I have reviewed this article according to the GA criteria and have failed the article at this time. The article is lacking any inline citations which is a requirement under the criteria. It would also be beneficial to add an infobox; look at WP:Bio for which one to use. Headings should only have the first word capitalized unless the word is a proper noun (Decline and Death should be Decline and death). Once you have addressed these issues, and have looked over the rest of the criteria, consider renominating again. Also consider getting a peer review to see how the article can be improved further. If you have any questions, let me know on my talk page and I'll get back to you as soon as I can. --Nehrams2020 06:21, 8 July 2007 (UTC)

GA revisited
Hello, here are my comments. So, I'll put the GA review on hold for the time being, attend to these points and get back to me for a re-review. Cheers. The Rambling Man 07:30, 1 August 2007 (UTC)
 * Ensure in-line citations are placed according to WP:CITE. Also, it's a lot nicer if the references are given titles rather than their simple URL's being shown at the bottom in the references section.  See WP:REF for more on this.
 * Early career and Ireland section contains several short paragraphs, I'd prefer to see them flowed together to form one or two larger paragraphs.
 * In Back in cabinet and the duel with Canning section, do tensions really cool or do they relax? Just read a bit strange to me!
 * Avoid single-sentence paragraphs.
 * Tenses are a bit mixed, i.e. "Later, he would learn..." vs "Stewart was elected..." for example.
 * (Just an aside, I found abstruse difficult to understand, so I looked it up and it turned out to mean... well... difficult to understand...!)
 * Last half of Decline and death section lacks citation, in particular statements like "His funeral on August 20 was greeted with jeering and insults along the processional route, although not to the level of unanimity projected in the radical press." need attribution otherwise may be considered original research.
 * When using paper references, it's best to actually cite the pages used as well as the books themselves, for a more thorough set of references.
 * Why is this categorised as Category:LGBT history of the United Kingdom?

LGBT History
Castlereagh's article is in Category:LGBT history of the United Kingdom because he was blackmailed for being homosexual - and in fact probably committed suicide for that very reason. I've replaced the cat and the project banner. -- SatyrTN (talk | contribs) 07:58, 6 August 2007 (UTC)
 * Well can it be referenced in the text with a citation then please? I can't find any mention of this in the article so it's unclear why it's tagged as such and should be removed unless suitable citable text is added.  The Rambling Man 08:01, 6 August 2007 (UTC)
 * I've added a ref to the quote. Let me know if you think the article (which is now on my watchlist) needs that section to be clearer. -- SatyrTN (talk | contribs) 08:19, 6 August 2007 (UTC)
 * That's great, but can we be even more specific in the text so that a non-familiar reader can understand the relevance of the blackmailing was? After all, you can be blackmailed for an awful number of things so I think you should make it clear that it was related to him being (accused of being) homosexual.  The Rambling Man 08:24, 6 August 2007 (UTC)
 * A little clearer? Does anything else need to be said? -- SatyrTN (talk | contribs)  08:37, 6 August 2007 (UTC)
 * Yes, that's perfect I think. The Rambling Man 08:53, 6 August 2007 (UTC)
 * I added a sentence making it clear that we don't know if he really was homosexual or bisexual, or if instead it was a function of his paranoia. I still think that this one statement, made under considerable duress, is a pretty flimsy reason to include him in the LGBT category, but I suppose it doesn't hurt. -- The_socialist talk? 21:06, 6 August 2007 (UTC)
 * The source I added says "There is no evidence to show that Castlereagh had any homosexual inclinations, although he has been credited with them." - . But it doesn't back that up with anything.  I'll see if I can find anything more for that. -- SatyrTN (talk | contribs)  06:41, 7 August 2007 (UTC)
 * Does anyone have ? -- SatyrTN (talk | contribs) 06:48, 7 August 2007 (UTC)

GA revisited, pass
Hello folks, sorry it's been a few days but I've been out of the country. I've looked over the changes made and I'm pleased to say that I think it's in a much better state. I've added a Further reading section as the in-line references and the bullet list of texts didn't look great. Anyway, enough of that, I'm promoting the article to GA and congratulate those involved in getting the article there. All the best, The Rambling Man 15:34, 8 August 2007 (UTC)

Regarded in Ireland...
The article states: "In Ireland he is always regarded, particularly by nationalists, as a traitor." I can find nothing in the given citation [] to support this. Moreover "always... particularly by nationalists" seems unlikely, since what nationalists would regard as treason (against Ireland, presumably) unionists would regard rather as praiseworthy.

I'm removing the line. If someone can find a supporting citation, a statement of the form "Irish nationalists regard[ed] him as..." might be in order. - Paul (talk) 00:48, 5 December 2007 (UTC)

Limavady
In the table at the bottom of this article it is not listed that Castlereagh was first elected to the Irish House of Commons in 1790 as a representative for county Down - although this is said in the text.

The table lists him as having been elected to represent Limavady in 1798 - I suspect though he never took up this seat as at the same time he was re-elected to County Down. The Limavady seat was perhaps a hedge against his possible failure to retain his Down seat.

If my supposition is correct Limavady would perhaps be best removed from the table. Certainly Down should be there.

Ned of the Hills 217.155.193.205 (talk) 08:58, 21 August 2008 (UTC)

Byron's epitath
The article sources the following version from.
 * Posterity will ne'er survey
 * A nobler grave than this:
 * Here lie the bones of Castlereagh:
 * Stop, traveller, and piss.

There is another version that, I personally think, is more likely to be correct:
 * Posterity will ne'er survey
 * A nobler scene than this.
 * Here lie the bones of Castlereagh.
 * Stop, traveller, and piss.

A quick Google comparison turns up ~370 hits for "grave" and ~250 hits for "scene". 87.234.117.197 (talk) 19:25, 24 April 2009 (UTC)

Requested move - April 2011

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the move request was: page moved. Vegaswikian (talk) 23:07, 5 May 2011 (UTC)

Robert Stewart, 2nd Marquess of Castlereagh → Robert Stewart, 2nd Marquess of Londonderry – The most senior peerage title is the convention by which peers are named in wiki. Even if they are commonly known by another name, this is to be entered in the lead, rather than the article name. The Castlereagh re-naming was an earlier error of mine. Apologies. Laurel Lodged (talk) 20:26, 28 April 2011 (UTC)
 * Where did you get that idea? The most common name is the name we should use in the title.  Powers T 22:35, 28 April 2011 (UTC)

 * Support — There never was a marquessate of Castlereagh. —Tamfang (talk) 01:49, 29 April 2011 (UTC)
 * Support. Probably could have been listed as an uncontroversial move. In answer to Powers's question (and to go slightly off topic), although we nearly always follow common name, nobility and royalty are a bit of an exception to this and we generally follow WP:NCROY in these articles (even though it's only a guideline, it has a large consensus and widespread usage). As an example, see Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge, neither of which are actually their most common name. Jenks24 (talk) 14:17, 30 April 2011 (UTC)
 * However, also see Frederick North, Lord North as another example of a prime minister better known by his courtesy title than his later inherited title. -- Necrothesp (talk) 15:30, 30 April 2011 (UTC)
 * However however, "Marquess of Castlereagh" is neither common nor correct. —Tamfang (talk) 08:54, 1 May 2011 (UTC)
 * Indeed, but Robert Stewart, Viscount Castlereagh may be more appropriate. -- Necrothesp (talk) 11:15, 1 May 2011 (UTC)
 * I have renamed the article to Robert Stewart, 2nd Marquess of Londonderry as this can clearly be speedied (Marquess of Castlereagh being simply incorrect and therefore providing false information to our readers), but we still need to decide whether to keep it here or to move it back to Robert Stewart, Viscount Castlereagh, which given the precedent and the fact that it was there until Laurel Lodged moved it I would now Support. -- Necrothesp (talk) 11:19, 1 May 2011 (UTC)
 * NCROY exists only because of the relative obscurity of many members of the nobility. It was put in place because no common name can be easily determined for the vast numbers of barely-notable nobility for whom we have articles.  It was not ever intended to override our WP:COMMONNAME guidelines, merely supplement it to provide structure and consistency when common names are hard to come by.  See, for instance, Queen Victoria.  Powers T 12:44, 1 May 2011 (UTC)
 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Whose Stupid Idea?
Since when did the title 'Marquess of Castlereagh' exist? As I could have sworn that Viscount Castlereagh was still the junior title held by the Marquess's eldest son an awful long time after, as otherwise Churchill wouldn't have referred to "That idiot Charlie Londonderry", whose son sat in the Commons as Viscount Castlereagh? —Preceding unsigned comment added by 82.21.148.189 (talk) 19:34, 29 April 2011 (UTC)

 * According to the last section, it was an admitted error by . —Tamfang (talk) 06:59, 30 April 2011 (UTC)

Retention permission.
Retain the current name per WP:NCROY. The exception of Lord North should not be followed. Indeed, that too should revert to the format of both his father and son. Also, propose to retain Robert Stewart, Viscount Castlereagh and Lord Castlereagh as re-directs to this page. Laurel Lodged (talk) 12:14, 1 May 2011 (UTC)
 * Who says that WP:Common supercedes WP:NCROY? Where is that written? Laurel Lodged (talk) 13:15, 1 May 2011 (UTC)

Retain per arguments given before. I don't see that wp:commonname supersedes wp:ncroy, and this way seems to be the case elsewhere. Boleyn (talk) 15:17, 1 May 2011 (UTC)

 * WP:COMMONNAME is part of WP:TITLE which is policy. NCROY is only a guideline.  And why is this conversation so disjointed?  Powers T 16:08, 1 May 2011 (UTC)

 * Disjointed probably because there have been three styles in question (and no one has explicitly said so): Marquess of Londonderry, the subject's highest title; Viscount Castlereagh, the courtesy title under which he became famous; and Marquess of Castlereagh, a nonexistent title to which this article was for a time erroneously renamed. —Tamfang (talk) 21:39, 1 May 2011 (UTC)

Requested move

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the move request was: move to Robert Stewart, Viscount Castlereagh. WP:NCPEER and WP:COMMONNAME are in agreement. Favonian (talk) 13:36, 11 July 2011 (UTC)

Robert Stewart, 2nd Marquess of Londonderry → Robert Stewart, Viscount Castlereagh – According to WP:NCROY, where someone is better known by a courtesy title, this should be used, as with e.g. Lord North. PatGallacher (talk) 09:28, 2 July 2011 (UTC)
 * Disagree Retain per arguments given before. I don't see that wp:commonname supersedes wp:ncroy, and this way seems to be the case elsewhere. Laurel Lodged (talk) 19:12, 2 July 2011 (UTC)
 * Reply NCROY clearly states: "When individuals became peers but are better known by a courtesy title, use that, e.g. Frederick North, Lord North (not 'Frederick North, 2nd Earl of Guilford'), Robert Stewart, Viscount Castlereagh (not 'Robert Stewart, 2nd Marquess of Londonderry')." So this is actually a case of following NCROY, not disregarding it.  The previous discussion was about moving away from "Marquess of Castlereagh", a title which was obviously incorrect. PatGallacher (talk) 19:55, 2 July 2011 (UTC)
 * Yes, this isn't a case of common name against WP:ncroy - the name proposed is the one that WP:NCROY implies, so there shouldn't be any controversy about this. (If we were to apply common name, we would use Lord Castlereagh, which I would support even more strongly, but given the prevailing superstition against doing anything so sensible, I'll confine myself to supporting the proposal.)--Kotniski (talk) 07:07, 11 July 2011 (UTC)
 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

I'm not sure I would strongly oppose Lord Castlereagh myself, but the present title is a clear improvement on the previous one. PatGallacher (talk) 17:41, 11 July 2011 (UTC)

Persed
Note 4: "Stewart ... persed his son to stand for the seat ..." Did you mean "pursed" (although that would be verbing a noun)? "pursued"? "dispersed"? Art LaPella (talk) 16:47, 1 December 2014 (UTC)

Responsibility for repressive measures
The second para contains the statement "Much more than prime minister Lord Liverpool, he was responsible for the repressive domestic measures."

As far as I can see, there's no evidence in the article to support this (nor in the standard biographies). It would be true to say, as it implies in the 'Decline and Death' section that his role as Leader of the House led to an association in the public mind with repressive acts, but he was no more personally responsible than any other member of cabinet, and rather less than Addington (and, probably, Liverpool).

Will edit the original sentence if no one objects — Preceding unsigned comment added by 87.112.174.69 (talk) 09:40, 18 June 2015 (UTC)

More ghostys
Elliott O'Donnell in his book on Gutenberg http://www.gutenberg.org/files/40823/40823-h/40823-h.htm describes a "yellow boy" who showed him how he would kill himself. It's in chapter iii. 104.229.139.131 (talk) 04:23, 1 February 2016 (UTC)

External links modified
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House of Orange
Castlereagh was instrumental in making the House of Orange kings of the Netherlands. One can argue that without his interference in 1813 this wouldn't have happened. I see it is not mentioned in the article. JRB-Europe (talk) 04:34, 12 August 2018 (UTC)

Change Citation Style
I would like to reorganise the way sources are cited in the article. I would like to see a list of cited sources and I would like to get rid of the "Further reading" section by citing the sources given there if possible. I would like to use the Sfn template in the text and provide quotes and URLs where possible. I would like to use the Citation template in the list of sources and again give URLs where possible. The references would become much easier to verify as the reader would be in most cases be able to read the relevant part of the source himself with a couple of mouse clicks. I think I need to call for a consensus      before implementing the changes. If there are no objections, I will consider that such a consensus exists and will make the corresponding changes after a delay of a month. Johannes Schade (talk) 15:11, 30 November 2019 (UTC)
 * No objection here. — howcheng  {chat} 16:51, 30 November 2019 (UTC)

The Radiant Boy
This legend seems to be associated with Ballyshannon in Donegal: https://ballyshannon-musings.blogspot.com/2017/11/a-famous-ballyshannon-ghost-story.html Corby Castle in Cumbria has a similar legend, although no Castlereagh connection: http://www.mysteriousbritain.co.uk/hauntings/corby-castle/ Shtove (talk) 11:09, 26 August 2020 (UTC)

Castlereagh, an "Ulster Scottish statesman"?
His grandfather, Alexander might be described as an Ulster-Scot, but given his maternal line, education, conversion to the Established Church, Castlereagh doesn't really benefit from such a description, especially as it was not current or understood in his circle. In some senses of the term, Anglo-Irish might also be misleading, but a "Irish and British statement" doesn't fit either, as he was only a statesman--whether as Chief Secretary for Ireland, or as Foreigh Secretary--in the direct service of the British government.ManfredHugh (talk)

 * Ethincally he is indeed best described as Ulster Scots, while belonging to the class of landed gentry (later aristocracy). His nationality, however, can be described as nothing other than British. Gaelicbow 14:54 Feb 3, 2024 (UTC)


text:
Robert Stewart, 1st Marquess of Londonderry

Robert Stewart, 1st Marquess of Londonderry PC (Ire) (1739–1821), was a County Down landowner, Irish Volunteer, and member of the parliament who, exceptionally for an Ulster Scot and Presbyterian, rose within the ranks of Ireland's "Anglican Ascendancy." His success was fuelled by wealth acquired through judicious marriages, and by the advancing political career of his son, Viscount Castlereagh (an architect of the Acts of Union, and British Foreign Secretary). In 1798 he gained notoriety for refusing to intercede on behalf of James Porter, his local Presbyterian minister, executed outside the Stewart demesne as a rebel.

Birth and origins
Robert was born on 27 September 1739, at Mount Stewart, the eldest son of Alexander Stewart and his wife Mary Cowan. His father was an alderman of Derry in 1760, and his grandfather, Colonel William Stewart, had commanded one of the two companies of Protestant soldiers that Derry admitted into its walls when Mountjoy was sent there by Tyrconnell before the start of the siege. Robert's mother was a daughter of John Cowan, also an alderman of that same town. His parents had married on 30 June 1737 in Dublin.

Cowan inheritance
Within three months of his parents' marriage in 1737, Robert's mother inherited the fortune her half-brother, Robert Cowan, had acquired in service to the East India Company as Governor of Bombay. The legacy allowed Alexander Stewart to retire from the linen trade and buy into the landed gentry. In 1743 he purchased sixty townlands and a large estate from the Colville family at Newtownards and Comber in County Down.

Education and first marriage
Robert Stewart was brought up a Calvinist, sent by his father under the care of a tutor to the University of Geneva, where he studied literature. He thus "temptations of Oxford and similar academic strongholds of the Established Church" to which, as the son landed gentry, he might naturally have been drawn.

On his return from the continent, he courted Lady Sarah Frances Seymour-Conway (whose niece, Mary Moore, married Robert's brother Alexander in 1791). Lady Sarah Frances Seymour-Conway's father, Francis Seymour-Conway, 1st Marquess of Hertford, owned considerable property in the neighbourhood of Lisburn, and in 1765 was appointed Lord Lieutenant of Ireland. Robert Stewart attended the viceregal court in Dublin, where he successfully pressed his suit. The marriage took place in the Chapel Royal of Dublin Castle, and Lord Hertford housed the new couple in the city.

Robert and Sarah had two sons:
 * 1) Alexander-Francis, who died within his first year
 * 2) Robert (1769–1822), later to be known as "Castlereagh", the famous statesman

Lady Sarah died in childbirth in 1770.

Opposition member of parliament
The year following his wife's death Robert Stewart entered the Irish House of Commons as member for County Down filling a vacancy created by the elevation of Bernard Ward to the House of Lords as Baron Bangor. He was returned by the "independent" or "county" interest backed by the local Whigs and by his fellow Presbyterians ("Dissenters" from the Established Church who were a majority among the county's exceptionally high number of freeholder voters). Their discomforted rivals were the "official" or "court" party of the Earl of Hillsborough, the county's Lord-Lieutenant and largest proprietor.

This political triumph over the interests of an Ascendancy family which had hitherto returned both county members to the Irish House of Commons formed the prelude of a long period of rivalry. Robert Stewart's initial success was largely due to popular sympathy with John Wilkes and the discontented American colonists, and to the growing feelings in favour of constitutional and parliamentary reform which found expression in the Volunteer movement.

He proved a consistent antagonist of the administration, invariably voting and sometimes speaking for the Opposition in the House. His early political conduct won the approval of his constituents. A dinner at which they entertained in Belfast was marked by toasts "liberal in quality as in quantity", including to "The memory of John Hampden" (who had led parliamentary opposition to Charles I), and to "All those who would rather die in jack-boots than live in wooden shoes".

Second marriage and children
Robert Stewart remarried, on 7 June 1775, taking for his second wife, Frances Pratt, the independent-minded daughter of the Whig politician Charles Pratt, 1st Earl Camden.

From his second marriage he had 11 more children, three sons and eight daughters:
 * 1) Charles William (1778–1854), succeeded him as 3rd Marquess
 * 2) Frances Ann (1777–1810), married Lord Charles Fitzroy
 * 3) Elizabeth Mary (1779–1798)
 * 4) Caroline (1781–1860), married Col. Thomas Wood MP
 * 5) Alexander John (1783–1800)
 * 6) Georgiana (1785–1804), married the politician George Canning, 1st Baron Garvagh, nephew of army general and politician Brent Spencer
 * 7) Selina Sarah Juliana (1786–1871), David Guardi Ker MP for Downpatrick
 * 8) Matilda Charlotte (1787–1842), married Edward Michael Ward, the eldest son of the Robert Ward of Bangor
 * 9) Emily Jane (1789–1865), married firstly John James, son of Sir Walter James James, 1st Baronet, and secondly Henry Hardinge, 1st Viscount Hardinge
 * 10) Thomas Henry (1790–1810)
 * 11) Octavia (1792–1819), married Edward Law, 1st Earl of Ellenborough

Irish Volunteer

Between 1775 and 1783, Robert Stewart lived in Bangor with his wife, while his father was living at Mount Stewart.

In 1776, a general election was held in Ireland. Robert Stewart stood again for Down and was re-elected. He sat until the dissolution of this parliament on 25 July 1783.

Stewart participated in the Irish Volunteers, the self-armed militia ostensibly formed to maintain order and defend Ireland while the Crown and its forces were distracted by the American War. Following the raid on Belfast Lough by the American privateer John Paul Jones in April 1778, Stewart organised a volunteer company in Newtownards of 115 men, the Arms Independents, to act as fencibles, but which, like other companies, were soon engaged in patriotic debate.

Alexander Stewart, died on 2 April 1781 and as his heir he moved into the family seat, Mount Stewart, near Newtownards (where in the park he completed the Temple of the Winds). On 17 September 1782 he was sworn to the Irish Privy Council.

That very same month as Colonel Stewart he was elected president of the second Ulster (overwhelmingly Presbyterian) Volunteer Convention in Dungannon.

Anticipating a "grand national convention" called for Dublin in November, it notably failed to broaden the front against the Ascendancy. Resolutions in support of Catholic enfranchisement were rejected.

In the general election of October Stewart stood again for County Down but the Ascendancy families triumphed, one seat taken by Arthur Hill, the son of the Earl of Downshire, the other by Lord Bangor's son, Edward Ward. Stewart unsuccessfully challenged the returns at the bar of the House of Commons claiming irregularities. Downshire's influence was able to procure the dismissal of his petition with costs".

At the Dublin convention, Stewart was appointed chairman of the committee "for the receiving and digesting plans of reform". But the convention tactic did not succeed as in 1781, when the massed ranks of the Volunteers had helped secure Irish legislative independence. The digested bill, presented by Henry Flood, which would have abolished the proprietary boroughs (with which their Ascendancy rivals, but not the Stewarts, were endowed) and extended the vote to a broader class of Protestant freeholders was rejected. Having accepted defeat in America, Britain could again spare troops for Ireland, and neither parliament nor Dublin Castle would again be intimidated.

Although he believed that the demands of Dissenters for greater representation should have been met so as to dissuade them from pushing Catholic claims along with their own, Stewart joined his friend, president of the convention, the Earl of Charlemont in urging the Volunteers to receive their rebuff quietly.

Ascendant peer
In 1789 Robert Stewart was created Baron Londonderry in the Peerage of Ireland. Unable as a peer to himself avenge his defeat in 1783, for general election of 1790 he took his eldest son, Robert, out of Cambridge University to run for the county. Still able to persuade Down's Forty-shilling freeholders that the Stewarts were the friends of reform, the younger Stewart did so successfully albeit at considerable expense to his father.

Stewart deserted Presbyterianism for the Established Church, at what point is unclear but likely in advance of his elevation in 1795 to Viscount Castlereagh and the following year to Earl of Londonderry. His eldest son, now Viscount Castlereagh, also quietly converted to Anglicanism and was appointed Chief Secretary for Ireland to serve under Lady Frances's brother, Earl Camden, the Lord Lieutenant. Londonderry's second son, Charles, meanwhile kept the family present in the Irish Commons as member for Thomastown borough, County Kilkenny. Banking on these new establishment connections, and alarmed by the evident disaffection of their tenantry, Stewart reached an accommodation with the Hills: the families in future would divide the two county seats in Down, each returning a nominee to the parliament in Dublin unopposed.

Following a theft of gunpowder and grapeshot in Donaghdee, on 26 September 1796, Londonderry summoned his tenants to Mount Stewart to compel them to sweat as oath of allegiance. To the extent that he and his sons were prepared to consider reform, including further rights for Catholics, it was now to be within the more secure context of a union with Great Britain. When in 1799 the parliament in Dublin rejected the bill for the Union they fought to have it re-presented.

With the bill's final passage, in 1801, Londonderry become one of the 28 original Irish representative peers in the new United Kingdom parliament at Westminster. In 1816, thanks to the advancing career of Castlereagh as Foreign Secretary, he was further elevated to Marquess of Londonderry. He thus achieved the rare feat of rising from a "Dissenting" (Presbyterian) commoner into the highest ranks of the Irish aristocracy.

1798, the execution of James Porter
During their three-day "Republic" in Ards and north Down, 10–13 June 1798, the United Irish insurgents briefly occupied Mount Stewart. In August, the wife of the local Presbyterian minister, James Porter, appeared at the house with her seven children where they overwhelmed Lady Londonderry and young sister, then dying of tuberculosis, with a plea for his life. One of the children was later to recount that when Londonderry discovered his wife composing a letter to General Nugent, he insisted she add a postscript: "L does not allow me to interfere in Mr Porter's case. I cannot, therefore, and beg not to be mentioned. I only send the letter to gratify the humour", i.e. to placate the distraught Mrs Porter to whom, with a smile that filed her with "much horror", Londonderry then handed the letter.

Londonderry was himself present at the court martial which had accepted dubious testimony to the minister's presence among the rebels, and was to see the sentence executed. Porter was hanged in sight both of his own meeting house at Greyabbey and of his family home (with Stewart tenants reportedly defying their landlord's wish that they attend). The Presbyterian minister Rev. Henry Montgomery of Killead, County Antrim, would later describe the circumstances of Porter's execution as being of "extreme cruelty towards both himself and his family, which were altogether unnecessary for any purpose of public example".

Londonderry was content that other offenders should be allowed exile. David Bailie Warden who commanded north Down rebels in the field; the Reverend Thomas Ledlie Birch, a United Irish firebrand who rallied with the rebels after the Battle of Saintfield; and William Sinclair who joined the tenantry in swearing loyalty before Londonderry yet served on the rebel Committee of Public Safety, were all permitted passage to the United States.

Porter's offence may have been his popular satire of the local landed interest, Billy Bluff, in which the master of Mount Stewart is clearly recognisable as the inarticulate tyrant "Lord Mountmumble". Porter had been aware that Billy Bluff might not go unpunished, acknowledging in its preface: "I am in danger of being hanged or put in gaol, perhaps both".

It may also be that Londonderry believed that Porter, who had been close to the family (their election agent and a frequent visitor to the Mount Stewart), had been a source of his wife's wayward, and potentially compromising, political sympathies. Lady Frances is rumoured to have continued to send privately for Porter's offending paper, the Northern Star, and in correspondence with Jane Greg (reputedly "head of the [ United Irish] Female Societies" in Belfast) made bold to identify herself as a "republican countess".

Local tradition has it that Mrs. Porter waylaid his lordship's carriage, in a vain hope of prevailing by a further direct entreaty, but Londonderry bade the coachman "drive on." The sentence, however, was mitigated by remission of the order for quartering.

Reputation as landlord
Despite political differences with his tenants, Londonderry did have a reputation as a comparatively generous landlord. He and his father rarely evicted tenants unless they were more than five years in arrears, and they abided by the Ulster custom of tenant right. They patronised the local town of Newtownards raising a subscription for a Catholic primary school as a gesture of ecumenical good will, and building a market house with a striking clock tower (a building which occupied by Scottish Fencibles was attacked by the rebels under Warden's command in 1798). During food shortages in 1800 and 1801, Londonderry at his own expense imported provisions into the stricken districts.

Death, succession, and timeline
Lord Londonderry died on 6 April 1821 at Mount Stewart, County Down, and was buried at the Newtownards Priory, where his father already had been laid to rest. He was succeeded briefly as the 2nd Marquess of Londonderry by his eldest son Robert (Castlereagh) who took his own life the following year.