Treatment of patients with febrile neutropenia (FN) attending Emergency Departments (EDs) relies on rapid antibiotic initiation in order to control a presumed infection. The choice of initial antibiotics is empirical and depends on patient's prior colonization or infection by multi-drug resistant pathogens (MDRPs) and risk stratification. Stratification of high-risk patients needing broad-spectrum antibiotics is debated. Thus, for non-specialist physicians, this choice may be challenging, leading to inappropriate initial antimicrobial regimens, potential risks for the patient and higher costs. Furthermore, international guidelines recommended to develop antibiotic stewardship programs and promoted an initial strategy based on escalation or de-escalation approaches, with early reassessment depending on patients' clinical course and microbiological results. Nevertheless, this interesting strategy may increase the level of complexity for the choice of the initial antibiotic regimen by non-specialist emergency physicians who are often the first prescribers in this context.

We developed an interactive computerized decision support app (CDSA) for initial antibiotic prescription and early revaluation in patients with FN. The first goal of this app is to assist non-specialized physicians in choosing initial antimicrobial regimen for patients with FN when they attend EDs. It uses an interactive algorithm based on international guidelines that takes into account patients' medical history and characteristics. Secondly, the app is also designed to propose an algorithm of antibiotic revaluation at day 3-4 for hospitalized patients, depending on patient clinical course, and biological and microbiological results. The revaluation suggests antimicrobial modification (escalation or de-escalation) or discontinuation and stopping rules with recommended duration of therapy also based on international guidelines.

We hypothesize that such a CDSA may improve the adherence to guidelines for the choice of initial antibiotic regimen for FN in the ED, favour early antibiotic reassessment for hospitalized patients, both decreasing the risk of treatment failure.

Inclusion Criteria:

• age ≥ 18 years;
• reported or observed fever at arrival at the ED (≥38.3° C on one occasion or ≥38°C on two or more occasions within 1 h);
• chemotherapy-induced neutropenia (absolute neutrophil count ≤500/mm3 or ≤1000/mm3 and anticipated to decrease to fewer than 500/mm3 within 24 to 48 h).

Exclusion Criteria:

• refusal to participate;
• prior inclusion in the study for a previous episode of FN;
• any intravenous antibiotic administration during the preceding 72 h;
• renal failure requiring renal replacement therapy or with an estimated creatinine clearance of less than 20 ml/min;
• palliative status with life expectancy of less than three days;
• pregnancy, absence of health insurance, mental deficiency or inability to understand informed consent, no French speaking;
• patient with a microbiological documented infection when arriving at the ED (e.g. positive blood culture).