inclusion criteria: age ≥ 18 years patients affiliated to social security scheme admission to an intensive care unit (icu) or intermediate care unit participating to the trial diagnosis of community- acquired pneumonia (cap) suggested by at least two of the following: cough, purulent sputum, chest pain and dyspnea focal shadowing/infiltrate on chest x-ray or ct-scan diagnosis of community- acquired pneumonia (cap) during the 48 hours post-hospital admission study drug infusion initiated no longer than 24 hours post first severity criterion severity defined by at least one of the following: pneumonia severity index (psi) > 130 (fine class v) patient placed on mechanical ventilation (invasive or not) for acute respiratory failure, with a peep level of 5 cm of water or more patient treated by high-flow oxygen therapy with a fio2 of 50% or more and a p/f ratio less than 300 patient treated by oxygen therapy with a partial rebreathing-mask with a reservoir bag, provided that the pao2 is less than (cf. table): oxygen flow (l/min) 6 7 8 9 10 or more pao2 (mmhg) less than 180 210 240 270 300 patient already treated by antibiotics (at least one dose since admission to hospital) informed consent signed by the patient, its relatives or emergency procedure on the sub-group of patients included with covid19 : diagnosis of covid19 either as certain (pcr) or probable (evocative clinical and radiological features and epidemic context and absence of other microbiological documentation). study drug infusion initiated no longer than 24 hours post first severity criterion ; in case of transfer from another hospital, this period will be prolonged to 48 hours patient receiving the best available treatment as define by up-to-date scientific knowledge

inclusion criteria: age ≥ 18 years patients affiliated to social security scheme admission to an intensive care unit (icu) or intermediate care unit participating to the trial diagnosis of community- acquired pneumonia (cap) suggested by at least two of the following: cough, purulent sputum, chest pain and dyspnea focal shadowing/infiltrate on chest x-ray or ct-scan diagnosis of community- acquired pneumonia (cap) during the 48 hours post-hospital admission study drug infusion initiated no longer than 24 hours post first severity criterion severity defined by at least one of the following: pneumonia severity index (psi) > 130 (fine class v) patient placed on mechanical ventilation (invasive or not) for acute respiratory failure, with a peep level of 5 cm of water or more patient treated by high-flow oxygen therapy with a fio2 of 50% or more and a p/f ratio less than 300 patient treated by oxygen therapy with a partial rebreathing-mask with a reservoir bag, provided that the pao2 is less than (cf. table): oxygen flow (l/min) 6 7 8 9 10 or more pao2 (mmhg) less than 180 210 240 270 300 patient already treated by antibiotics (at least one dose since admission to hospital) informed consent signed by the patient, its relatives or emergency procedure on the sub-group of patients included with covid19 : diagnosis of covid19 either as certain (pcr) or probable (evocative clinical and radiological features and epidemic context and absence of other microbiological documentation). study drug infusion initiated no longer than 24 hours post first severity criterion ; in case of transfer from another hospital, this period will be prolonged to 48 hours patient receiving the best available treatment as define by up-to-date scientific knowledge