Zoé Van De Wyngaert

Céline Berthon

Houria Debarri

Claire Bories

Sarah Bonnet

Morgane Nudel

Benjamin Carpentier

Charline Legrand

Sarah Barbieux

Paul Chauvet

Arthur Simonnet

Alexandre Willaume

Jean-Baptiste Bossard

Loic Renaud

Kevin James Wattebled

Guillaume Escure

Nicolas Branche

Ines Arib

Marie Titecat

Bruno Quesnel

Serge Alfandari

MD Zoe Van De Wyngaert

Discontinuation of antimicrobial therapy in adult neutropaenic haematology patients: a prospective cohort

Keywords: Acute Myeloblastic Leukaemia, antibiotics discontinuation, febrile neutropaenia, ECIL-4

Objectives. Antibiotics for febrile neutropaenia, in acute myeloid leukaemia (AML) patients undergoing intensive chemotherapy, are usually maintained until neutropaenia resolution, because of the risk of uncontrolled sepsis in this vulnerable population. This leads to unnecessarily prolonged antimicrobial therapy. Methods. Based on ECIL-4 recommendations, we modified our management strategy and discontinued antibiotics after a pre-established duration, among patients treated for a first episode of febrile neutropaenia between August 2014 and October 2017. Results. Antibiotics were stopped during 62 febrile neutropaenia episodes, and maintained in the control group (n=13). Median age was 54 years. 39 (63%) patients received induction and 23 (37) consolidation chemotherapy. 36 (58%) patients had fever of unknown origin. Median neutropaenia length was 26 days [IQR 24-30]. Antibiotics were started at day 9 [5-13]. Most patients received piperacillin-tazobactam (56%) or cefepime (32%). Antimicrobial therapy was longer in the control group compared with the policy compliant group, 10 [7-16] vs. 19 days [15-23], p=.0001. After antibiotics discontinuation, 20% patients experienced fever recurrence, within 5.5 days [3-7.5]. None of these febrile episodes were severe. 80% patients remained afebrile, with neutrophil recovery occurring within five days [2-8.5]. Overall, 287 antibiotics days were spared; this represents 49% of all days with antibiotics. No patient had died at day 30 from intervention; six died during late follow-up, two from Graft-versus-Host disease and four from relapsed or refractory leukaemia.

Conclusions. Discontinuing antibiotics in neutropaenic AML patients treated for a first episode of febrile neutropaenia is safe, and results in significant antibiotic sparing.

Introduction.

Acute myeloblastic leukaemia (AML) patients undergoing intensive chemotherapy are considered at high risk for severe infections, because of a deep (<0.1x10 9 /L) and prolonged (>7 days) neutropaenia. Febrile neutropaenia (FN) will occur in 70 to 80% of these patients [START_REF] Freifeld | Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 Update by the Infectious Diseases Society of America[END_REF][START_REF] Knockaert | Fever of unknown origin in adults: 40 years on[END_REF]. Because of the neutropaenia and the low bacterial inoculum, 60% of patients will present with fever of unexplained origin (FUO), defined by fever with no clinical or microbiological documentation, despite thorough investigations [START_REF] Freifeld | Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 Update by the Infectious Diseases Society of America[END_REF][START_REF] Knockaert | Fever of unknown origin in adults: 40 years on[END_REF]. Initial treatment of FN should take into account previous documented infections, colonization with resistant bacteria, and hospital ecology. In our centre, according to US and European recommendations, we commonly use an escalation strategy, where initial empirical therapy is based on a beta-lactam covering typical Enterobacteriacae and Pseudomonas aeruginosa, but not extended-spectrum beta-lactamase (ESBL), carbapenemase producers, nor multi-resistant non-fermenters. Therapy is escalated, to carbapenems or with adjunction of aminoglycosides, if patient deteriorates, or if a resistant pathogen is isolated. Glycopeptides are used in seriously-ill patients (hemodynamic instability, severe pneumonia), in cases of colonisation with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci, or penicillin-resistant S. pneumoniae, skin or soft-tissue or catheter-related infection [START_REF] Freifeld | Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 Update by the Infectious Diseases Society of America[END_REF][START_REF] Averbuch | European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: summary of the 2011 4th European Conference on Infections in Leukemia[END_REF].

The Infectious Diseases Society of America (IDSA) recommends maintaining antimicrobial therapy (AMT) until resolution of neutropaenia (i.e. absolute neutrophil count > 0.5x10 9 /L) [START_REF] Freifeld | Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 Update by the Infectious Diseases Society of America[END_REF]. This is justified by the risk of uncontrolled sepsis in this vulnerable population. However, it leads to prolonged AMT, which increases the risk of multi-resistant bacteria selection, puts pressure on the colonising microbial flora, leading to colitis with Clostridium difficile or colonisation with yeasts, and can be responsible for pharmacological toxicity, including encephalopathy or nephropathy [START_REF] Deshayes | Neurological Adverse Effects Attributable to beta-Lactam Antibiotics: A Literature Review[END_REF][START_REF] Schalk | Clostridium difficile-associated diarrhoea, a frequent complication in patients with acute myeloid leukaemia[END_REF][START_REF] Ben-David | Outcome of carbapenem resistant Klebsiella pneumoniae bloodstream infections[END_REF][START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF]. Furthermore, non-bacterial agents, such as viruses or fungi, may cause some of these undocumented febrile episodes. Some may also have a noninfectious origin, such as acute transfusion reactions, or allergic reaction to chemotherapy.

Early studies addressing the issue of antibiotic discontinuation in neutropaenic patients showed an increased risk of severe infection and mortality [START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF]. Therefore, antibiotic discontinuation was considered unsafe. However, these conclusions have been challenged by more recent studies. It was shown that fever recurrence can occur whether antibiotics are stopped during neutropaenia or after its resolution, and that, with appropriate AMT and monitoring, non-severe FUO has low mortality, even in high-risk haematology patients [START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF]. Therefore, the 4th European Conference on Infections in Leukaemia (ECIL-4) published guidelines stating that AMT can be discontinued after ≥72 hours of intravenous (IV) treatment, in selected patients with non-severe FUO who are afebrile for ≥48 hours, irrespective of the absolute neutrophil count (ANC) or expected duration of neutropaenia. If fever recurs, AMT should be started again promptly [START_REF] Averbuch | European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: summary of the 2011 4th European Conference on Infections in Leukemia[END_REF].

Based on these recommendations, we modified our management strategy among newly diagnosed adult AML patients, receiving intensive chemotherapy, and treated for a first episode of non-severe febrile neutropaenia, and introduced AMT discontinuation after a preestablished duration, whatever the absolute ANC.

Material and methods.

Population.

Our antibiotic policy is reviewed and updated each year in discussions between haematologists, infectious diseases physicians and microbiologists. This antibiotic discontinuation policy was decided and implemented in August 2014. Although this paper reports results of a routine policy change, and not a clinical study, for clarity purpose, we will use the terms "inclusion/included" to define patients concerned by the new policy and "exclusion/excluded" for those unconcerned by the policy.

We included consecutive patients, admitted to our university hospital between August 2014 and October 2017. Inclusion criteria were age ≥18 years, new diagnosis of AML or myeloid sarcoma, first-line treatment with intensive chemotherapy, and first non-severe episode of FN, including FUO, primary bacteraemia and focal infections. The policy change also included patients who had an orthopaedic implant, had been admitted in the intensive care unit (ICU) for sepsis or septic shock during a previous hospital stay or were colonized with multiresistant bacteria. One patient could be included several times in our study, but during a different neutropaenic episode and a different hospital stay (e.g. during induction and consolidation phases).

Exclusion criteria were Acute Lymphoblastic Leukaemia (ALL) diagnosis, relapse or refractory patients, previous hematopoietic stem-cell transplant (HCST), non-intensive treatment, severe infection (i.e. sepsis or septic shock, according to the recent definition [START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF]), severe infection such as endocarditis or osteomyelitis, presence of prosthetic heart valve, as these patients were considered too frail and/or at higher risk for severe infectious complications. In these patients, antibiotics were maintained until neutropaenia resolution.

Antimicrobial therapy discontinuation.

Initial empirical therapy was given intravenously (IV) in all cases. It was mostly based on a beta-lactam covering typical Enterobacteriacae and P. aeruginosa (e.g. cefepime or piperacillin-tazobactam). Narrower-spectrum beta-lactam (cefotaxime) was used when fever occurred within the first week of hospitalization. Carbapenem or adjunction of an aminoglycoside was used if a resistant pathogen was isolated. Glycopeptides were used in cases of skin, soft-tissue or catheter-related infection.

AMT was discontinued after at least seven days of intravenous treatment, after resolution of clinical symptoms and at least five days of apyrexia, regardless of the ANC or the predicted duration of neutropaenia. Duration of AMT was determined according to clinical presentation and/or microbiological documentation: seven days for FUO, colitis or pneumonia, ten days for catheter-related infection or bacteraemia, ten days for urinary tract infection in female patients, and 14 days for male patients. Patients were thoroughly monitored. In case of febrile recurrence, the same antibiotics were started again urgently by ward nurses (a standing order allowed for immediate treatment without medical prescription), and maintained until neutrophil recovery. Adjunction of antifungal treatment was discussed according to clinical presentation, duration of neutropaenia, indirect fungal biomarkers (galactomannan antigen), and thoracic CT-scan.

We do not use antibiotic prophylaxis with fluoroquinolones due to the high level of resistance to fluoroquinolones in our population. All patients received an antifungal prophylaxis with oral posaconazole during neutropaenic period.

Endpoint.

Our primary endpoint was the occurrence of a new febrile episode after AMT discontinuation.

Secondary endpoints were number of days without antibiotics, occurrence of severe infections, and 30-days mortality.

Statistics.

Data collected prospectively were analysed retrospectively. Outcomes were compared between the groups with the t test or Mann-Whitney U test for continuous outcomes and with the χ2 or Fisher's exact test as appropriate for contingency analysis. P values of 0.05 were considered significant. Statistical analysis was performed using Microsoft Excel v.12.2.8 (MS Office 2008) and GraphPad Prism v.7.0.

Ethics.

This study was conducted in accordance with the ethical standards of our hospital committee on human experimentation, and with the Helsinki Declaration of 1975, as revised in 2008. We did not submit this study to a formally constituted review board because the subject of this article was the analysis of a major antibiotic policy change performed to follow European guidelines (ECIL-4) for AML patients. Per French law at the time, review of usual care in monocentric studies did not require submission to an ethical review committee. Patients' usual physicians collected all data analyzed as part of routine diagnosis and treatment.

Results.

Flow-chart.

Between August 2014 and October 2017, 98 patients eligible for intensive treatment were newly diagnosed with AML or myeloid sarcoma in our university hospital. Each patient received at least one intensive treatment course (induction and/or consolidation); number of hospital stays (hence, number of neutropaenic episodes) was 195 overall, as patients could be included more than once, but over different hospital stays. Thirty-five neutropaenic episodes were excluded because of hospitalization in the ICU, due to AML complication or severe infection (sepsis or septic shock). During 45 neutropaenic episodes, patients remained afebrile. Finally, 115 episodes of non-severe FN were included. AMT was not discontinued in 66 episodes (58%): neutrophil recovery occurred before the planned end of antibiotic treatment in 35 episodes (30%); apyrexia couldn't be obtained before neutrophil recovery in 18 episodes (16%); and in 13 episodes (11%), AMT was not stopped because of physicians' failure to follow the new policy. We chose to use these 13 episodes as a control group. AMT was effectively stopped in 49 non-severe febrile neutropaenic episodes (Figure 1).

Population.

Patients' characteristics are described in Table 1 Overall, 47 patients had AML, including eight Acute Promyelocytic Leukaemia (APL), one had biphenotypic AML treated as an AML, and one had myeloid sarcoma. Induction chemotherapy was based on anthracyclines, either daunorubicin, or idarubicin given during three to five days, in combination with cytarabine (200mg/m 2 /day) given by continuous intravenous infusion during seven days. One patient received amsacrine combined with cytarabine. Consolidation chemotherapy consisted of cytarabine alone, 1 to 3g/m 2 /12h over 3 days, according to physician judgment. APL patients were treated according to APL2006 protocol, or with arsenic trioxide in combination with all-trans retinoic acid.

Control group.

Antibiotics were not stopped in 13 FN episodes (occurring among 13 patients) because of physicians' failure to follow the new policy. These patients were used as a control group.

Reasons for maintaining antibiotics were because patients were considered too frail (n=5), uncontrolled infection (n=1); no reasons were identified for the seven remaining patients.

Even though there were no statistically significant differences between the two groups, control patients had more aggressive underlying disease, with poor prognosis cytogenetics and higher tumour burden at admission (defined by either leukocyte count >50G/l, intravascular disseminated coagulation, or spontaneous tumour lysis syndrome). This could explain physicians' reluctance to discontinue antibiotics among these patients.

Febrile neutropaenia.

Febrile neutropaenia occurred during induction therapy for 39 (63%) episodes and during consolidation therapy for 23 (37%) episodes. FUO occurred in 36 episodes (58%). Clinical symptoms were upper respiratory tract symptoms (n=4) or pneumonia (n=5), catheter-related infection (n=4), colitis (n=1), dental abscess (n=1), endometritis (n=1). We obtained microbiological documentation in 16 (26%) cases. Blood cultures were positive in eight patients, with gram-negative rods (n=5) or streptococci (n=2), one patient having concomitant E. coli and S. oralis bacteraemia. Two patients had several positive blood cultures with coagulase-negative staphylococci (Staphylococcus hominis and S. epidermidis, respectively).

One patient had clinical signs of catheter infection, with significant Staphylococcus epidermidis growth at removal and culture. Three asymptomatic patients had positive urine culture. One female patient presented with E. coli endometritis. In four patients with upper respiratory tract symptoms, nasal swab was positive for viruses (Table 2).

Antimicrobial therapy.

Empirical AMT was initiated immediately after the first episode of FN. Four patients (6%) received cefotaxime as monotherapy (100mg/kg/day IV divided in 3 doses). Most patients received antipseudomonal beta-lactam, either piperacillin-tazobactam, 4g/6-8h IV (n=35, 56%) or cefepime, 2g/8h IV (n=20, 32%), mostly given as monotherapy (n=41, 66%).

Combination therapy with amikacin was given in patients with known ESBL colonization (n=5, 8%), or signs that could suggest severe infection but without sepsis criteria such as mottled skin (n=3, 5%). Anti methicillin-resistant staphylococci therapy (vancomycin or linezolid) was given in case of skin or catheter-related infection (n=6, 10%). One patient with ESBL colonization was given a carbapanem, meropenem. One patient with colitis was treated with cefepime and metronidazole. One patient received vancomycin alone for S. hominis bacteremia. The patient diagnosed with E. coli endometritis initially received ceftriaxone, metronidazole, and doxycycline (Table 3). AMT was considered adequate, following standard guidelines for FN and according to our center ecology, and when microbiological documentation was available, appropriate, in 46 (94%) patients in the policy compliant group and 12 (92%) in the control group.

As expected, effective AMT was longer in the control group. In the policy compliant group, antibiotics were discontinued as planned in FUO (n=28; 7.5 days [START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF][START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF]) and catheter-related infections and/or bacteraemia (n=10; 10 days [START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF]). However, for other clinical situations, antibiotics were given for a longer time than recommended. Reasons were persistence of clinical symptoms (n=7) and fever recurrence (n=2).

We observed adverse events in 20 (32%) patients; all were considered mild or moderate (grade 1-2). Most of them are not specific, and might also be caused by anti-leukaemia chemotherapy.

Outcome.

Median neutropaenia length was 26 days [IQR [START_REF] La Martire | De-escalation and discontinuation strategies in high-risk neutropenic patients: an interrupted time series analyses of antimicrobial consumption and impact on outcome[END_REF][START_REF] Madran | Implementation of an antimicrobial stewardship program for patients with febrile neutropenia[END_REF][START_REF] Schmidt-Hieber | Management of febrile neutropenia in special consideration of the role of antimicrobial de-escalation[END_REF][START_REF] Theuretzbacher | Global antimicrobial resistance in Gram-negative pathogens and clinical need[END_REF][START_REF] Kaye | Infections Caused by Resistant Gram-Negative Bacteria: Epidemiology and Management[END_REF][START_REF] Gyssens | The role of antibiotic stewardship in limiting antibacterial resistance among hematology patients[END_REF][30] in the overall population, 27 days [START_REF] Madran | Implementation of an antimicrobial stewardship program for patients with febrile neutropenia[END_REF][START_REF] Schmidt-Hieber | Management of febrile neutropenia in special consideration of the role of antimicrobial de-escalation[END_REF][START_REF] Theuretzbacher | Global antimicrobial resistance in Gram-negative pathogens and clinical need[END_REF][START_REF] Kaye | Infections Caused by Resistant Gram-Negative Bacteria: Epidemiology and Management[END_REF][START_REF] Gyssens | The role of antibiotic stewardship in limiting antibacterial resistance among hematology patients[END_REF][30][31][32][33][34] for patients undergoing induction phase and 24 days [START_REF] Aguilar-Guisado | Optimisation of empirical antimicrobial therapy in patients with haematological malignancies and febrile neutropenia (How Long study): an open-label, randomised, controlled phase 4 trial[END_REF][START_REF] Clech | Early discontinuation of empirical antibacterial therapy in febrile neutropenia: the ANTIBIOSTOP study[END_REF][START_REF] La Martire | De-escalation and discontinuation strategies in high-risk neutropenic patients: an interrupted time series analyses of antimicrobial consumption and impact on outcome[END_REF][START_REF] Madran | Implementation of an antimicrobial stewardship program for patients with febrile neutropenia[END_REF][START_REF] Schmidt-Hieber | Management of febrile neutropenia in special consideration of the role of antimicrobial de-escalation[END_REF][START_REF] Theuretzbacher | Global antimicrobial resistance in Gram-negative pathogens and clinical need[END_REF] for patients in consolidation phase (Table 4). One patient never had neutrophil recovery, and was discharged at day 43.

In the overall population, AMT was started after a median nine days [IQR 5-13] since chemotherapy, and was given for ten days [START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF][START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF][START_REF] Link | Interventional antimicrobial therapy in febrile neutropenic patients. Study Group of the Paul Ehrlich Society for Chemotherapy[END_REF]. During the induction phase, AMT was started on day six [START_REF] Averbuch | European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: summary of the 2011 4th European Conference on Infections in Leukemia[END_REF][START_REF] Deshayes | Neurological Adverse Effects Attributable to beta-Lactam Antibiotics: A Literature Review[END_REF][START_REF] Schalk | Clostridium difficile-associated diarrhoea, a frequent complication in patients with acute myeloid leukaemia[END_REF][START_REF] Ben-David | Outcome of carbapenem resistant Klebsiella pneumoniae bloodstream infections[END_REF][START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF], and given for 17 days [START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF][START_REF] Link | Interventional antimicrobial therapy in febrile neutropenic patients. Study Group of the Paul Ehrlich Society for Chemotherapy[END_REF][START_REF] Santolaya | Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Micol | Discontinuation of empirical antibiotic therapy in neutropenic acute myeloid leukaemia patients with fever of unknown origin: is it ethical?[END_REF][START_REF] Orasch | Discontinuation of empirical antibiotic therapy in neutropenic leukaemia patients with fever of unknown origin is ethical[END_REF]; during consolidation, it was started on day 14 [11.5-17], and given for nine days [START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF][START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF]. AMT length was significantly higher in the control group compared with the policy compliant group, 10 days [START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF][START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF] vs. 19 days [START_REF] Shankar-Hari | Developing a New Definition and Assessing New Clinical Criteria for Septic Shock: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3)[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF][START_REF] Link | Interventional antimicrobial therapy in febrile neutropenic patients. Study Group of the Paul Ehrlich Society for Chemotherapy[END_REF][START_REF] Santolaya | Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Micol | Discontinuation of empirical antibiotic therapy in neutropenic acute myeloid leukaemia patients with fever of unknown origin: is it ethical?[END_REF][START_REF] Orasch | Discontinuation of empirical antibiotic therapy in neutropenic leukaemia patients with fever of unknown origin is ethical[END_REF][START_REF] Aguilar-Guisado | Optimisation of empirical antimicrobial therapy in patients with haematological malignancies and febrile neutropenia (How Long study): an open-label, randomised, controlled phase 4 trial[END_REF][START_REF] Clech | Early discontinuation of empirical antibacterial therapy in febrile neutropenia: the ANTIBIOSTOP study[END_REF], p=0.0001 (Figure 2). This was true for both induction and consolidation phases. There were no differences in neutropaenia length, or antibiotic initiation day between the groups.

After AMT discontinuation, in the policy compliant group, ten patients (20%) experienced a new febrile episode and 39 (80%) achieved neutrophil recovery without febrile recurrence.

Febrile recurrence occurred for nine patients (18%) during induction phase, and for one (2%) during consolidation. Treatment phase was not associated with significantly higher risk of fever recurrence (p=0.08). Median duration between AMT interruption and new febrile episode was 5.5 days [3-7.5] in the overall population, six days [START_REF] Averbuch | European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: summary of the 2011 4th European Conference on Infections in Leukemia[END_REF][START_REF] Deshayes | Neurological Adverse Effects Attributable to beta-Lactam Antibiotics: A Literature Review[END_REF][START_REF] Schalk | Clostridium difficile-associated diarrhoea, a frequent complication in patients with acute myeloid leukaemia[END_REF][START_REF] Ben-David | Outcome of carbapenem resistant Klebsiella pneumoniae bloodstream infections[END_REF][START_REF] Sallah | Analysis of factors related to the occurrence of chronic disseminated candidiasis in patients with acute leukemia in a non-bone marrow transplant setting: a follow-up study[END_REF][START_REF] Wey | Risk factors for hospital-acquired candidemia. A matched case-control study[END_REF] for induction phase, and three days for the patient in consolidation phase. None of these ten febrile episodes led to hemodynamic instability, septic shock, or ICU hospitalization. Eight episodes (80%) presented as FUO; febrile recurrence was asymptomatic but microbiologically documented in the two (20%) remaining patients: one had Escherichia coli bacteraemia, and another had Streptococcus mitis bacteraemia. Interestingly, both of them initially presented as a FUO.

Use of relatively narrow-spectrum antibiotics such as cefotaxime was associated with higher risk of fever recurrence (p=0.0009). However, use of monotherapy vs. combination therapy (p=0.43) or use of penicillin vs. cephalosporin (p=0.9) had no significant impact on the risk of fever recurrence.

Patients who achieved neutrophil recovery without fever recurrence were equally distributed between induction (n=19, 39%) and consolidation phase (n=20, 41%). Median overall duration between AMT discontinuation and neutrophil recovery was five days [IQR 2-8.5],

eight days [4.5-12.5] in the induction group and two days [START_REF] Freifeld | Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 Update by the Infectious Diseases Society of America[END_REF][START_REF] Knockaert | Fever of unknown origin in adults: 40 years on[END_REF][START_REF] Averbuch | European guidelines for empirical antibacterial therapy for febrile neutropenic patients in the era of growing resistance: summary of the 2011 4th European Conference on Infections in Leukemia[END_REF][START_REF] Deshayes | Neurological Adverse Effects Attributable to beta-Lactam Antibiotics: A Literature Review[END_REF][START_REF] Schalk | Clostridium difficile-associated diarrhoea, a frequent complication in patients with acute myeloid leukaemia[END_REF][START_REF] Ben-David | Outcome of carbapenem resistant Klebsiella pneumoniae bloodstream infections[END_REF] in the consolidation group.

As AMT is usually maintained until neutrophil recovery, this corresponds to the number of days of antibiotics spared. Overall, patients received antibiotics during 845 days, and 586 days in the policy-compliant population. Our management strategy allowed us to spare 287 days of AMT; this represents 34% of the overall consumption, and 49% for the policycompliant population.

Mortality.

No patient had died at day 30 from antibiotics discontinuation. Three-year overall survival (OS) was 75%. Median OS was not reached. Median follow-up was 19 months. Overall, six patients (12%) died during follow-up. Two patients underwent allogeneic stem-cell transplant and died of severe GVHD, six and eight months after diagnosis, respectively. Four patients died of AML: three relapsed, and died three years, 19 and 16 months after initial diagnosis, respectively; one had refractory leukaemia and died ten months after diagnosis.

The main result of our study is that discontinuing AMT, in patients treated for a first episode of FN, is safe, regardless of the ANC. Indeed, 80% patients remained afebrile until neutrophil recovery. Among the 20% patients with a recurrent febrile episode, the outcome was favourable, without any severe sepsis, ICU admission or death. AMT length was significantly higher among patients with compliance failure to the new policy. Implementation of the new strategy resulted in high antibiotic sparing, a mean 6 days per patient, similar in patients with or without a second febrile episode. In the policy compliant population, 49% of all days with antibiotics were spared.

Most of first and second febrile episodes occurred remotely from each other. Febrile recurrences were diagnosed a median six days and up to 14 days after AMT discontinuation.

These episodes are probably independent events, as it seems unlikely that the same microorganism could be incriminated in both episodes. Blood cultures at the time of febrile recurrence were positive in only two patients, who both initially presented as FUO. Previous studies reported that recurrence of fever might occur whether or not AMT is discontinued [START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF]. Patients probably present several infectious episodes during prolonged neutropaenia, with different microorganisms, and that could be another reason to discontinue AMT, as it might allow for better microbiological documentation and lead to de-escalation therapy.

ECIL-4 guidelines state that AMT can be discontinued after at least three days of IV treatment, in patients with non-severe FUO who are afebrile for ≥48 hours. Before these guidelines, standard of care in our unit was to discontinue AMT after neutrophil recovery.

Changing clinical practices is challenging, especially in the absence of randomized controlled study to support these paradigm-changing recommendations. We decided to adapt the guidelines to our centre habits, hoping for a better appropriation by our prescribers. We thus chose to discontinue AMT after at least seven days of IV treatment and five days of apyrexia.

In contrast, we extended indications of antibiotic discontinuation to cases of documented fever, whereas ECIL-4 recommendations only refer to FUO episodes, which concerned 58% of our population.

However, in our study, a high number of patients were excluded due to neutrophil recovery before AMT cessation. This accounts for 35 patients (30%) overall, most of them (91%) being in consolidation phase. This could reflect the longer duration of antibiotic therapy used in this study, compared to ECIL-4 guidelines, and indicates that we could probably align our strategy more closely to ECIL-4 guidelines. This is especially true for patients in consolidation phase, who are probably a lower risk group with shorter neutropaenic period. A tighter application of ECIL-4 guidelines could probably save even more AMT days. Discontinuation of AMT in neutropaenic patients is not a new topic, but remains controversial. [START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF], provided the first study addressing this question. They included 33 patients with FUO after chemotherapy for solid neoplasia or hemopathy, randomized between stopping or continuing treatment after seven days of empirical AMT.

Seven patients (41%) in the experimental arm relapsed, with five documented febrile episodes, and two septic deaths due to E. coli bacteraemia, vs. only one fever recurrence and no deaths in the standard group. Antibiotic discontinuation was thus considered unsafe in neutropaenic patients. Later, [START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF], conducted a randomized study among 60 high and low-risk haematology patients, in which empirical AMT was stopped after 48 hours of apyrexia. They showed that febrile recurrence occurred both in neutropaenic (9/49, 18%) and non neutropaenic patients (2/11, 18%). One neutropaenic patient died from an invasive fungal infection. Slobbe et al. included 169 high-risk haematology patients, receiving fluoroquinolone and fluconazole prophylaxis. Imipenem was stopped after ≤72 hours in cases of FUO, or switched to narrower spectrum antimicrobial agents according to microbial documentation. There were no differences between fever recurrence, severe infections or death among the different groups. ECIL-4 guidelines were published in 2013, based on these studies and others [START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF][START_REF] Link | Interventional antimicrobial therapy in febrile neutropenic patients. Study Group of the Paul Ehrlich Society for Chemotherapy[END_REF][START_REF] Santolaya | Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study. Clinical infectious diseases : an official publication of the[END_REF].

To our knowledge, few prospective studies have been published since then. One prospective French study by Micol et al. included seven high-risk neutropaenic patients with FUO.

Antimicrobial therapy was discontinued after a mean of 15 days, which is longer than the ECIL-4 recommendations; four patients remained afebrile, with neutrophil recovery achieved within two to four days, and three patients had recurrent fever in less than three days, with one septic shock. AMT was spared for a mean of three days, but authors considered that exposing patients to a risk of uncontrolled secondary infections was unethical. However, interpretation of this study is controversial, and was commented by others [START_REF] Micol | Discontinuation of empirical antibiotic therapy in neutropenic acute myeloid leukaemia patients with fever of unknown origin: is it ethical?[END_REF][START_REF] Orasch | Discontinuation of empirical antibiotic therapy in neutropenic leukaemia patients with fever of unknown origin is ethical[END_REF]. It is noteworthy that the patient undergoing septic shock was the only one receiving salvage therapy, underlying the importance of patients' selection.

Recently, one Spanish team conducted a multicentric randomized study among 157 high-risk neutropaenic haematology patients with FUO [START_REF] Aguilar-Guisado | Optimisation of empirical antimicrobial therapy in patients with haematological malignancies and febrile neutropenia (How Long study): an open-label, randomised, controlled phase 4 trial[END_REF]. AMT was stopped after ≥72h of apyrexia in the experimental group, or withdrawn at neutrophil recovery. Mean AMT length was 11.9 days in the experimental group and 14.4 days in the control group. This allowed a significant spare of 2.5 days of AMT (p=0.026). The frequency of recurrent fever was similar in both groups, (11 patients (14%) in the experimental group and 14 (18%) in the control group, p=0.54), with only one severe infection; no patient died after AMT withdrawal. However, in our opinion, this study has some limits. First, the overall population is heterogeneous, and includes patients that are at lower risk for FN (81 patients, 52%), such as patients receiving chemotherapy for lymphoid malignancies, including autologous stem cell transplant; these patients are expected to have duration of neutropaenia of 7 days or more, but neutropaenia is usually not as deep as in AML patients or allogeneic stem cell recipients (76 patients, 48%).

There are more low-risk patients in the control group, and neutropaenia length is therefore shorter, 11 (8.0-21.3) vs. 14 days (9.5-24) in the experimental group. Secondly, only 41 (53%) patients were still neutropaenic at AMT withdrawal in the experimental group; the reason for this is unclear. Although results of this study are encouraging, this may limit extrapolation of these findings. Interestingly, our median antibiotic duration (10 days) was similar to the one reported in this study, despite having a longer apyrexia requirement before AMT discontinuation.

A French observational study included 82 cases of FN; antibiotics were discontinued whatever the ANC, according to ECIL-4 guidelines. Forty-eight (58%) FUO episodes did not relapse during hospital-stay and 14 (17%) had fever recurrence, without excessive in-hospital mortality or intensive care unit admission [START_REF] Clech | Early discontinuation of empirical antibacterial therapy in febrile neutropenia: the ANTIBIOSTOP study[END_REF]. Rates of fever recurrence are similar to what we observed in our study, and in others, published before ECIL-4 guidelines [START_REF] Pizzo | Duration of empiric antibiotic therapy in granulocytopenic patients with cancer[END_REF][START_REF] Joshi | Can antibacterial therapy be discontinued in persistently febrile granulocytopenic cancer patients?[END_REF][START_REF] Cherif | A prospective, randomized study comparing cefepime and imipenem-cilastatin in the empirical treatment of febrile neutropenia in patients treated for haematological malignancies[END_REF][START_REF] Slobbe | Three-day treatment with imipenem for unexplained fever during prolonged neutropaenia in haematology patients receiving fluoroquinolone and fluconazole prophylaxis: a prospective observational safety study[END_REF][START_REF] Cornelissen | Discontinuation of intravenous antibiotic therapy during persistent neutropenia in patients receiving prophylaxis with oral ciprofloxacin. Clinical infectious diseases : an official publication of the[END_REF][START_REF] Horowitz | Stepdown single agent antibiotic therapy for the management of the high risk neutropenic adult with hematologic malignancies[END_REF][START_REF] Hodgson-Viden | Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia[END_REF][START_REF] Jones | Risk factors for recurrent fever after the discontinuation of empiric antibiotic therapy for fever and neutropenia in pediatric patients with a malignancy or hematologic condition[END_REF][START_REF] Link | Interventional antimicrobial therapy in febrile neutropenic patients. Study Group of the Paul Ehrlich Society for Chemotherapy[END_REF][START_REF] Santolaya | Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study. Clinical infectious diseases : an official publication of the[END_REF].

Another study, conducted by la Martire et al., aimed at evaluating the impact of an antibiotic stewardship intervention on antibiotic consumption. Antibiotic discontinuation was performed among 52/100 FN episodes. Surprisingly, no fever recurrence during the same neutropaenic episode was observed. Compared to our population, neutropaenia length was significantly shorter (19 [12-29] vs. 26 [START_REF] La Martire | De-escalation and discontinuation strategies in high-risk neutropenic patients: an interrupted time series analyses of antimicrobial consumption and impact on outcome[END_REF][START_REF] Madran | Implementation of an antimicrobial stewardship program for patients with febrile neutropenia[END_REF][START_REF] Schmidt-Hieber | Management of febrile neutropenia in special consideration of the role of antimicrobial de-escalation[END_REF][START_REF] Theuretzbacher | Global antimicrobial resistance in Gram-negative pathogens and clinical need[END_REF][START_REF] Kaye | Infections Caused by Resistant Gram-Negative Bacteria: Epidemiology and Management[END_REF][START_REF] Gyssens | The role of antibiotic stewardship in limiting antibacterial resistance among hematology patients[END_REF][30][31] days); this could explain the higher fever recurrence rates observed in our study [START_REF] La Martire | De-escalation and discontinuation strategies in high-risk neutropenic patients: an interrupted time series analyses of antimicrobial consumption and impact on outcome[END_REF].

Management of FN has changed over the past years. The overall tendency to the prudent use of AMT is justified by the global increase in antibiotic resistance in hospitalized patients and in the community. Several studies have shown that antibiotic stewardship leads to improved AMT use, and decreases antibiotic consumption [START_REF] Madran | Implementation of an antimicrobial stewardship program for patients with febrile neutropenia[END_REF][START_REF] Schmidt-Hieber | Management of febrile neutropenia in special consideration of the role of antimicrobial de-escalation[END_REF]. Antibiotic resistance is a special concern for haematology patients, who undergo several chemotherapy-induced neutropaenia episodes, and are exposed to repeated courses of broad-spectrum AMT [START_REF] Theuretzbacher | Global antimicrobial resistance in Gram-negative pathogens and clinical need[END_REF][START_REF] Kaye | Infections Caused by Resistant Gram-Negative Bacteria: Epidemiology and Management[END_REF][START_REF] Gyssens | The role of antibiotic stewardship in limiting antibacterial resistance among hematology patients[END_REF].

Our study has limitations. First, it is a monocentric cohort based on a small population.

Nevertheless, our patients are standard AML patients, included consecutively, who, in our opinion, reflect the overall population of patients with AML. Second, the lack of a control group with patients recruited prospectively limits the impact of our results. However, having observed no adverse effect at all of the new strategy, a control group could not have yielded better results. One of the reasons may be the automatic standing order for readministration of AMT in patients with a new febrile episode. Third, this study, following a policy change, might be biased in patients' selection. However, in our centre, only two haematology physicians manage AML patients, with twice weekly rounds by a consulting infectious disease physician, resulting in a homogenous management of the patients.

Conclusions.

In conclusion, antibiotic discontinuation in patients newly diagnosed with acute myeloid leukaemia, and presenting a first episode of febrile neutropaenia after receiving intensive chemotherapy, is not only feasible but also safe, provided that appropriate AMT is started again promptly after fever recurrence. This strategy reduces antibiotic use, and does not increase the rate of severe infections or mortality in high-risk haematology patients.

Fig. 1 .Fig

 1 Fig. 1.

  . Overall, 36 patients were included in the policy compliant group and 13 in the control group. Median age was 54 years overall [interquartile range (IQR) 36-63]. Four patients (8%) had previous known ESBL colonization.

Declarations

CBe, HD and SA formulated the research question, and designed the study.

CBo, SBo, MN, BC, CL, SBa, PC, AS, AW, JBB, LR, KJW, GE, NB, IA included patients, collected data of tolerance, efficacy and follow-up.

ZV included patients, collected and analyzed data, and wrote the manuscript draft.

CBe, SA, BQ and MT revised the manuscript.

All authors read and approved the final version of this manuscript.


Edwin-Joffrey Courtial

Clément Perrinet

Arthur Colly

David Mariot

Jean-Marc Frances

René Fulchiron

Christophe Marquette

Hicham Bidaoui
email: bidaouihicham@gmail.com

Ikram El Abbassi

Abdelmajid El Bouardi

Abdelmoumen Darcherif

Silicone rheological behavior modification for 3D printing: Evaluation of yield stress impact on printed object properties

Keywords: Weibull distribution, Rayleigh distribution, Wind speed, Probability density function, Wind rose

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

In recent years, world's energy consumption has been increasing due to economic and social development in both modern and emergent countries. The fast growing energy demand is particularly visible in Africa. While the world energy production reached 13 790 Mtoe in 2015, the African continent saw its consumption rose to 8% versus 0.6% in 2014. While, energy demand rose only by 0.5% in non-OECD (Organization for Economic Co-operation and Development) countries. and decreased by 0.3% in OECD [1].

Wind is one of the most important renewable energy sources. Indeed, the wind energy is well developed, controlled and accessible. However, in order to increase wind farm's electrical production performance in a given location, a deep analysis of wind characteristics is required [2], [3]. Recently, researchers have shown increased interest in wind energy potential in several regions of the world using miscellaneous probability density functions (PDF). In this paper, Weibull and Rayleigh PDFs are used to describe wind speed probability in five cities in Northern Morocco (Fig. 1); they are the most widely used in literature, as well as their good accuracy in describing and predicting wind speed distribution in many regions of the world PDF.

The objective here is threefold i) to find the theoretical model closest to the experimental reality for extrapolation to other geographical areas in the southern Mediterranean, ii) to determine among the five cities those with the best potential Wind turbine, iii) and to use the models in the sizing of wind farms according to the geographical specificities of the site.

Nomenclature

Materials and methods

Dual-fed antenna design Weibull probability and cumulative distribution function

It's the widely two parameters distribution function used in literature for describing wind speed data in many regions. The variations in wind velocity are characterized by two functions: "The probability density function" and "The cumulative distribution function". The first function indicates the percent of time for which the wind flows with a specific wind speed. It's mathematically expressed as follow [4], [5]:

1 exp k k w k v v f (v) . c c c -        = -                 (1)
The cumulative distribution function gives the percent of time that the wind speed is less than or equal the wind speed v0, it's expressed by the integral of the probability density function.

0 ( ) 1 exp k v F v v c     ≤ = - -          
(2)

Rayleigh probability and cumulative distribution function

The Rayleigh distribution, which is a special case of Weibull distribution with a fixed shape parameter value k=2, is defined by

[6], [7]: 2 2 ( ) exp 4 2 r m m v v f v v v π π       = -        (3)
The Rayleigh cumulative distribution function is given by:

2 0 ( ) 1 exp 4 m v F v v v π       ≤ = - -        (4)

Extrapolation of wind speed at different hub height

The observed data used in this study were measured at 10m height. While most of commercial wind turbine have different hub height. The Hellman's exponential law was used to extrapolate wind speed data to adequate height to our study (110m) [8], [9]:

0 0 z z v v z α   =     (5)
It's assumed to be 0.143 in coastal regions and 0.2-0.3 in forested area, or evaluated by the following equation: 2 0 0.37 0.088ln( ) / 1 0.088ln 10

z c α     = - -             (6)

Fig. 1 .

 1 Fig. 1. Map of the locations of measurement stations.


Sammy Badr

Isabelle Legroux-Gérot

Jean Vignau

Christophe Chauveau

Stefan Ruschke

Dimitrios C Karampinos

Jean-François Budzik

Bernard Cortet

Anne Cotten

Thibaut Capron
email: thibaut.capron@ap-hm.fr

Youssef Trigui

Clarisse Gautier

Basile Puech

Pascal Chanez

Martine Reynaud-Gaubert

Comparison of regional bone marrow adiposity characteristics at the hip of underweight and weight-recovered women with anorexia nervosa using magnetic resonance spectroscopy

Keywords: Niemann-Pick, Acid sphingomyelinase deficiency, pulmonary storage disorder, lung transplant, hemoptysis

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Acid sphingomyelinase deficiency (ASMD) is a rare lysosomal storage disorder caused by autosomal recessive genetic mutations in the SMPD1 gene. It has been historically termed as Niemann-Pick disease. Patients reaching adulthood often exhibit interstitial lung disease although rarely presenting respiratory symptoms. This is a reason why this disease remains poorly known from pulmonologists, whereas new diagnostic recommendations and promising therapeutics are rising. We present two case reports illustrating respiratory impairment in such patients with referral to the pulmonologist. We briefly review and discuss typical aspects of the disease and related up-to-date challenges for the pulmonologist.

Case report #1:

A 50-year-old man was referred to our center for the worsening of his respiratory status and assessment for lung transplantation.

He had been diagnosed with Niemann-Pick disease type B six years ago, following the exploration of increased dyspnea revealing an interstitial lung disease. He reported only a 20 pack-years smoking history as background. The computed tomography (CT) scan found an interstitial pattern and revealed hepatosplenomegaly for which he was referred to the hematologist. Vacuolated macrophages were found in bone marrow and a storage disorder was suspected. In order to ascertain diagnosis, the patient benefited from wedge lung resection, which confirmed interstitial infiltration with lipid-laden cells compatible with Gaucher's disease. Deficiency of the acid sphyngomyelinase enzyme activity in blood was observed and the final diagnosis of Niemann-Pick type B disease was set. Genetic analysis of the SMPD1 gene yielded the homozygous deletion p.R610, without family background for such a disease.

After the diagnosis, the patient stopped follow-up for 5 years. He was referred back to pulmonologist due to progressively increased dyspnea. He quit smoking one year before, required continuous 2 L/min oxygen support and was treated with 10 mg corticosteroid per day.

According to this worsening respiratory condition, he was referred to our lung transplantation center.

On admission, blood arterial gases revealed hypoxemia (PaO2 55 mmHg) without hypercapnia.

Pulmonary function testing evidenced a moderate restriction (Forced Vital Capacity FVC 75 % theorics) with lowered diffusion capacity for carbon monoxide (DLCO 45 % theorics).

6-minutes walk distance test (6MWD) performed under continuous 4 L/min oxygen support showed decreased saturation down to 84 % with 480 m distance walked. Thoracic CT scan found diffuse abnormalities along a cranio-caudal gradient. They consisted of ground-glass opacities with intermixed intralobular lines and interlobular septal thickening (Figure 1a-c), characteristic of the so-called "crazy-paving" pattern. Infra-centimetric mediastinal nodes were also noted. Global comparison with anterior results drew the conclusion of a smooth slow deterioration.

On the cardiovascular side, echocardiography did not show any sign of cardiac dysfunction or pulmonary hypertension. Coronarography was normal. Arterio-venous vascular axes were free from significant lesion. Liver function was normal and portal hypertension was ruled out.

Biology found isolated low platelet count to 93 G/L and hyperlipidemia with high level of triglycerides and low level of high-density lipoprotein (HDL). Renal and hepatic functions were normal. Previous abdominal CT scan found spleen nodules with, on ultrasound, an aspect of angioma.

Finally the evaluation did find indication for lung transplantation with a very motivated patient reporting major alteration of his quality of life. No contraindications were noted. Information and psychological support were provided to the patient and he has been placed on the waiting list for double lung transplantation 3 months later.

Case report #2 :

A 44-years old caucasian man referred to pulmonologist with moderate hemoptysis. He had never smoked and had been diagnosed with Niemann-Pick disease type B at the age of 3 years old, following the exploration of hepatosplenomegaly. The patient had only minor dyspnea for important efforts as respiratory symptoms, and lung interstitial pattern was discovered on CT 5 years before. Genetic analysis of SMPD1 is in progress and there was no family history of the disease. The patient also had symptomatic hiatal hernia treated by proton pump inhibitors.

He consulted for an intermittent hemoptoic productive cough since nearly one month, without thoracic pain nor fever. He was not febrile, and clinical examination did not find signs of respiratory failure. Blood pressure and oxygen saturation were normal and cardio-pulmonary auscultation did not reveal any significant findings.

Laboratory blood examinations found preserved hemoglobin and low platelet count to 111 G/L, reticulocyte count was slightly elevated to 91 G/L. C reactive protein, renal function and coagulation were normal. Dyslipidemia was noted with slightly elevated triglycerides and low HDL cholesterol level.

Thoracic CT scan showed bilateral lower lobes ground glass opacities associated with intermixed intralobular and interlobular lines in upper lobes (Figure 2). Emphysema lesions were observed in apical regions whereas very distal bronchiolectasis were noticeable in basal lungs (Figure 3).

Because of profuse basal ground glass opacities in relation with the chronic disease, no additional sign of alveolar hemorrhage could be diagnosed on CT. There was neither vascular target for embolization nor evidence for the origin of bleeding.

Flexible bronchoscopy with bronchoalveolar lavage (BAL) revealed an active bleeding from the right lower lobe (segmental lateral basal B9). A radial endobronchial ultrasound probe was used to confirm the absence of endobronchial lesions in this segment and in the upstream segment. BAL was macroscopically hemorrhagic and showed elevated cell count. The BAL cultures were negative for bacteria, mycobacteria and fungi. No malignant cells were found.

Differential cell count provided 8 % neutrophils, 3 % lymphocytes and 89 % macrophages comprising 7 % hemosiderin-laden macrophages with a Golde score of 95.

The diagnosis of alveolar hemorrhage was retained and the patient started therapy with oral prednisolone 1mg/kg per day without any improvement.

Pulmonary function tests were unchanged as compared to 2014 with preserved volumes (FVC 93 % theorics) and mild alteration of diffusing capacity (DLCO 54 % theorics). The patient did not present any desaturation in 6MWD.

Immunological blood analyses including anticytoplasmic antibodies (myeloperoxidase and proteinase 3), antiglomerular basal membrane antibodies, antinuclear antibodies, rheumatoid factor and antibodies to citrullinated peptide were negative. No drugs could be incriminated in the alveolar hemorrhage. Specifically, there was no current epistaxis or gingival hemorrhage episodes that could point out a role of the relative thrombocytopenia.

Finally, the patient had isolated recurrent low-abundance hemoptysis with signs of idiopathic alveolar hemorrhage and impairment of his quality of life. In the absence of specific treatment, close follow-up was proposed to the patient.

Review of ASMD and discussion

ASMD is a lysosomal storage disorder commonly known as Niemann-Pick disease type A (NPD A) and Niemann-Pick disease type B (NPD B) [START_REF] Schuchman | Types A and B Niemann-Pick disease[END_REF]. NPD A patients have mainly neurological impairment and a poor prognosis with a median lifespan of 3 years after birth. In contrast, NPD B patients reach adulthood, show very variable disease course and a broader spectrum of clinical manifestations including pulmonary involvement [START_REF] Wasserstein | The natural history of type B Niemann-Pick disease: results from a 10-year longitudinal study[END_REF][START_REF] Guillemot | Lung disease in Niemann-Pick disease[END_REF]. While typical NPD B patients do not exhibit neurological manifestations, a subset of patients termed "variant NPD B" may have mild-to-severe peripheral neurological symptoms (4). The Niemann-Pick disease type C, initially grouped with ASMD, is however driven by other pathogenesis, different genetic disorders and central nervous system is mainly involved. NPD A and B classifications were historically based on clinical presentation but owing to the various manifestations and severity levels of the disease, it might be more appropriated to report them as pathogenenesis-based ASMD disease (4). The estimated incidence of ASMD is approximately 0.5 per 100 000 births [START_REF] Mcgovern | Disease manifestations and burden of illness in patients with acid sphingomyelinase deficiency (ASMD)[END_REF].

Pathogenesis is caused by mutations in the SMPD1 gene, coding for acid sphingomyelinase. Such mutation results in lower enzymatic activity and abnormal accumulation of lipids in cells, predominantly macrophages and hepatocytes. This deposition disease evolves slowly and progressively and may impair multiple organs. Histopathological analyses typically show lipid-laden cells, so-called "foam cells" in liver, spleen, lymph nodes, adrenal cortex, lungs and/or bone marrow. Specifically for the lung, lipid-laden cells accumulate in the alveolar septa, bronchial walls and subpleural spaces [START_REF] Marten | Imaging of macrophage-related lung diseases[END_REF].

A major challenge for the pulmonologist is to identify ASMD patients [START_REF] Hervé | Niemann-Pick disease type B identified following an episode of bronchopneumonia[END_REF], due to the scarcity and the heterogeneity of the disease. Overall, storage disorder should be suspected in patients presenting with hepatosplenomegaly and interstitial lung disease (Figure 1). Indeed, such patients almost systematically have pulmonary involvement detectable by imaging, but without respiratory symptoms. In the largest prospective case series, common symptoms were splenomegaly (78 %) and hepatomegaly (73 %). The most common complaints were bleeding (49 %, recurrent epistaxis in 29 %), pulmonary infections (42 %), shortness of breath (42 %) and joint/limb pain (39 %) [START_REF] Mcgovern | A prospective, cross-sectional survey study of the natural history of Niemann-Pick disease type B[END_REF]. Clinical manifestations may also include developmental delay or retina cherry-red maculae [START_REF] Cox | Burden of Illness in Acid Sphingomyelinase Deficiency: A Retrospective Chart Review of 100 Patients[END_REF]. Thrombocytopenia and mixed dyslipidemia are typical biological features reported in NPD B patients [START_REF] Mcgovern | A prospective, cross-sectional survey study of the natural history of Niemann-Pick disease type B[END_REF][START_REF] Hollak | Acid sphingomyelinase (Asm) deficiency patients in The Netherlands and Belgium: disease spectrum and natural course in attenuated patients[END_REF]. This dyslipidemia is characterized by low high-density-lipoprotein (HDL) cholesterol and high levels of low-density-lipoprotein (LDL) cholesterol and triglycerides.

Respiratory impairment ranges from absence of symptoms to rare chronic failure [START_REF] Minai | Pulmonary involvement in Niemann-Pick disease: case report and literature review[END_REF][START_REF] Von Ranke | Pulmonary Involvement in Niemann-Pick Disease: A State-of-the-Art Review[END_REF].

Mainly reported respiratory symptoms are dyspnea on mild exertion and recurrent infections.

As illustrated in case #1, the disease may evolve towards oxygen requirement and reduced tolerance to exercise. Some studies reported that pulmonary disease is the most debilitating clinical feature in NPD B patients [START_REF] Hollak | Acid sphingomyelinase (Asm) deficiency patients in The Netherlands and Belgium: disease spectrum and natural course in attenuated patients[END_REF] and retrospective compelling of the data from ASMD deceased patients found that overall leading causes of death were respiratory failure and liver failure (27 % each) [START_REF] Cassiman | Cause of death in patients with chronic visceral and chronic neurovisceral acid sphingomyelinase deficiency (Niemann-Pick disease type B and B variant): Literature review and report of new cases[END_REF].

Interstitial lung disease is the most prominent feature found in prospective surveys, concerning 90-98 % of NPD B patients [START_REF] Mcgovern | A prospective, cross-sectional survey study of the natural history of Niemann-Pick disease type B[END_REF][START_REF] Mendelson | Type B Niemann-Pick disease: findings at chest radiography, thin-section CT, and pulmonary function testing[END_REF], predominantly in the lower lobes. However the severity of imaging assessment does not correlate with the lack of alteration of pulmonary function tests [START_REF] Mendelson | Type B Niemann-Pick disease: findings at chest radiography, thin-section CT, and pulmonary function testing[END_REF]. Indeed, pulmonary function tests can demonstrate normal lung volumes or mild restrictive pattern, with a slight alteration of the diffusion capacity for carbon monoxide. Longitudinal follow-up highlighted a gradual but slow deterioration of pulmonary function over time, reflecting a slow progression of the disease (2,10).

Bronchoalveolar lavage is helpful to highlight lipid-laden macrophages characteristic of lipoid pneumonia (15) but is not specific for Niemann-Pick disease. Lung biopsy samples allow for studying morphology and topography of the infiltration with lipoid cells, which is necessary for the pathologist to argue for diagnosis of metabolic disorder [START_REF] Rossi | The role of macrophages in interstitial lung diseases: Number 3 in the Series "Pathology for the clinician" Edited by Peter Dorfmüller and Alberto Cavazza[END_REF]. Typical features are large multivacuolated histiocytes staining deep blue with MGG, so-called Niemann-Pick cells or "sea-blue histiocytes".

Chest CT identifies ground-glass opacities, mild smooth interlobular septal thickening and intralobular lines, predominantly in the lower lung regions. Such mixed observations form the so-called "crazy-paving" pattern [START_REF] Mendelson | Type B Niemann-Pick disease: findings at chest radiography, thin-section CT, and pulmonary function testing[END_REF][START_REF] Freitas | Niemann-Pick disease type B: HRCT assessment of pulmonary involvement[END_REF].

For the first patient presented above, CT imaging during an acute dyspnea episode one year before is shown on figure 1-d. Numerous bilateral ground-glass opacities were visible and had disappeared one year after (figure 1-b). Clinical evolution was spontaneously favorable without any treatment in the absence of positive microbiological documentation. This suggests exacerbations of the disease with radiological reversible lesions, which are not described in ASMD and may be interpreted as low respiratory tract infection episode in view of the symptoms and the chest radiograph.

The second patient had unusual lesions on CT imaging: apical emphysema and very distal bronchiolectasis in lower lobes (Figure 3). Comparison with previous CT performed 5 years before demonstrated slow progression of these anomalies. Bronchial distortion and subpleural emphysema-like lesions were also identifiable in our first patient (Figure 1-a). Following the model of macrophage-related interstitial lung diseases in cigarette smokers, macrophage dysfunction can induce emphysema or fibrosis [START_REF] Marten | Imaging of macrophage-related lung diseases[END_REF]. Our cases may suggest an additional alveolar macrophage dysfunction, which could be related to the progression of respiratory impairment.

Main features of the two cases presented above are summarized in table 1. These reports highlight the concerns for the pulmonologist in ASMD disease, especially when respiratory impairment does develop. Actually, several series of patients identified respiratory impairment as a major cause of death [START_REF] Cassiman | Cause of death in patients with chronic visceral and chronic neurovisceral acid sphingomyelinase deficiency (Niemann-Pick disease type B and B variant): Literature review and report of new cases[END_REF][START_REF] Mcgovern | Morbidity and mortality in type B Niemann-Pick disease[END_REF]. Onset of respiratory symptoms may thus be viewed in favor of the intensification of the treatment and care.

The clinical presentation depicted earlier is highly suggestive of lysosomal storage disorder but is shared by Gaucher's disease. Hepatosplenomegaly and pulmonary impairment may also occur, with abnormal pulmonary function tests and similar interstitial pattern on CT [START_REF] Gülhan | Different features of lung involvement in Niemann-Pick disease and Gaucher disease[END_REF]. As illustrated in our first case report, histopathological analyses may also fail to discriminate the two diseases. Following recent consensus guidelines, first-intention measurement of acid sphingomyelinase enzymatic activity provides the differential diagnosis [START_REF] Mcgovern | Consensus recommendation for a diagnostic guideline for acid sphingomyelinase deficiency[END_REF]. This can be reliably done in peripheral blood lymphocytes or cultured skin fibroblasts. Simultaneous determination of the glucocerebrosidase activity in blood, which is specifically lowered in Gaucher's disease, is also recommended. Genetic detection of pathogenic SMPD1 variants may bring diagnostic information but should be reserved to second-intention analysis after enzymatic diagnosis, due to the variety of mutations of unknown significance. These diagnostic recommendations are summarized as an algorithm in recent consensus expert guidelines [START_REF] Mcgovern | Consensus recommendation for a diagnostic guideline for acid sphingomyelinase deficiency[END_REF].

Management of ASMD is currently based on symptomatic treatment and supportive care.

Whole lung lavage, based on pulmonary alveolar proteinosis protocols, has shown efficacy in few cases reports but remains a high-risk procedure with only temporary benefit [START_REF] Nicholson | Successful treatment of endogenous lipoid pneumonia due to Niemann-Pick Type B disease with whole-lung lavage[END_REF][START_REF] Lau | Whole lung lavage for lipoid pneumonia[END_REF].

Importantly, splenectomy has to be avoided as it may worsen hyperlipidemia profile [START_REF] Mcgovern | A prospective, cross-sectional survey study of the natural history of Niemann-Pick disease type B[END_REF], whereas updated vaccination is warranted. Potential effect of steroids remains an open question in guidelines for clinical management [START_REF] Wasserstein | Recommendations for clinical monitoring of patients with acid sphingomyelinase deficiency (ASMD)[END_REF].

Promising new enzyme replacement therapies are rising with the potential to modify the natural history of the disease. Results of a phase 1 trial of recombinant human acid shingomyelinase in ASMD patients have been published in 2016 [START_REF] Mcgovern | Novel first-dose adverse drug reactions during a phase I trial of olipudase alfa (recombinant human acid sphingomyelinase) in adults with Niemann-Pick disease type B (acid sphingomyelinase deficiency)[END_REF] and results of phase 1b study are about to be announced [START_REF] Lidove | Acid sphingomyelinase deficiency (Niemann-Pick disease Type B) as an inflammatory disease[END_REF]. Clinical development is continuing with an ongoing phase 2/3 trial in ASMD adults [START_REF] Lidove | Acid sphingomyelinase deficiency (Niemann-Pick disease type B) in adulthood: A retrospective multicentric study of 28 adult cases][END_REF].

It is worthwhile to notice that our first patient was contraindicated to enzyme replacement therapy trial because of the severity of his respiratory condition, raising again interest in an earlier diagnosis.

Another end-stage treatment that could be considered by pulmonologist is lung transplantation, as illustrated in case #1. Very recently, a first case reporting such procedure in a patient with NPD B was published. Diffuse alveolar damage occurred on the lung allograft, attributed to major influx of recipient-derived lipid-laden macrophages and patient died at day 29 [START_REF] Mannem | Lung transplantation in a patient with Niemann-Pick disease[END_REF].

While it was proposed that such reaction could be prevented using enzyme replacement therapy [START_REF] Lidove | Acid sphingomyelinase deficiency (Niemann-Pick disease Type B) as an inflammatory disease[END_REF], a second case of successful lung transplantation was reported [START_REF] Ding | Successful lung transplantation in a patient with Niemann-Pick disease[END_REF]. The authors applied standard immunosuppression protocol and emphasized that normal liver function plays a fundamental role in protecting the lung allograft. Lung transplantation candidates should thus be carefully checked-up for liver function and portal hypertension.

Interestingly, these two patients showing severe NPD B also presented upper-lobe emphysema, consistent with our two cases descriptions of severity. Moreover, these recent publications on lung transplantation in NPD B confirm the growing referral of these patients to the pulmonologist.

Conclusion

Acid sphingomyelinase deficiency is a rare disease with growing concerns for the pulmonologist. Almost all patients present asymptomatic interstitial lung disease and few of them exhibit respiratory symptoms for which they can be referred to the pulmonologist. Early diagnosis is still currently limited by the lack of awareness of healthcare professionals. Storage disorder should be suspected when combined with hepatosplenomegaly and typical biologic abnormalities; diagnosis should be confirmed following recent expert consensus guidelines based on first-intention measurement of enzymatic activity.

The disease is slowly but irremediably progressive and this has to be taken into account in order to adapt therapeutics or refer the patients for lung transplantation. Unlike in other interstitial pulmonary diseases such as fibrosis, no clear steeper degradation signal is currently appreciable. However, cases discussed in this review suggest that emphysema or marked bronchiolectasis may be a marker for more severe respiratory impairment.

Enzyme replacement therapy is very promising and involves pulmonologist for early diagnosis, follow-up of respiratory function and referral to expert centers. Potentially, efficient therapy improvements would intensify discussions around newborn screening for such storage disorders in the future [START_REF] Wasserstein | The New York pilot newborn screening program for lysosomal storage diseases: Report of the First 65,000 Infants[END_REF].

FiguresFigure 1 :

 1 Figures

Figure 2 :

 2 Figure 2: chest computed tomography of case#2. a: upper lobes with apical emphysema and b: septal thickening. c: middle-lung mixed interlobular and intralobular lines with ground glass opacities. d: lower lobes with ground glass and distal bronchiolectasis.

Figure 3 :

 3 Figure 3: chest computed tomography with minip coronal reconstruction for case#2. Left: whole lung coronal view illustrating cranio-caudal gradient and variety of lesions. Right: focus

Table 1 :

 1 summary of clinical and analyses findings in our two cases. "Red flag symptom" is the symptom that made ASMD diagnosis evoked. "Unusual features" note the original features presented in these cases not reported in previous literature.

	Diagnostic age (yrs)	44	3
	Red flag symptom	Hepatosplenomegaly	Hepatosplenomegaly
	Family cases/SMPD1 mutations	None/homozygous p.R610del	None/in progress
	Acid sphingomyelinase activity	Low	Low
	Main complaint	Dyspnea	Hemoptysis
	Thrombopenia	Mild	Mild
	Dyslipidemia	HyperTg, low HDL	HyperTg, low HDL
	Other biological anomaly	None	Elevated reticulocytes
	Respiratory impairment	Hypoxemia PaO2 55 mmHg	Daily hemoptysis
	Pulmonary function tests	Mild restrictive syndrome FVC 75 %, lowered KCO 45 %	Normal lung volumes, lowered KCO 54 %
	Chest imaging	Mixed interlobular and intralobular lines, ground-glass opacities	Mixed interlobular and intralobular lines, ground-glass opacities
	Extra-thoracic disease	Spleen nodules	None
	Unusual features	Subpleural emphysema, disease exacerbations	Emphysema, bronchiolectasis, alveolar hemorrhage

Acknowledgments

We acknowledge fruitful discussions on chest imaging with Pr J.-Y. Gaubert and Dr P. Habert, but also concerning clinical management of these cases with Dr K. Mazodier, Dr C. Stavris, Dr G. Thomas, Dr J.-B. Rey, Dr E. Prud'homme and J. Bermudez.