BetaLACTA® Test for Early De-escalation of Empirical Carbapenems in Pulmonary, Urinary and Bloodstream Infections in ICU

This study is conducted on ICU patients with a suspected pneumonia, primary blood-stream infection (BSI), and/or urinary tract infection (UTI). The primary objective of the study is to demonstrate that in ICU infections treated empirically by carbapenems and documented with GNB on direct examination of a respiratory, urinary and/or blood sample(s), the early de-escalation guided by the results of the betaLACTA® test is not inferior to the reference strategy de-escalating on antibiotic susceptibility test (AST) results obtained 48-72h after sampling, in terms of mortality at D90 and infection recurrence in ICU. The secondary objectives are to compare the early de-escalation guided by the betaLACTA® test results to the reference strategy de-escalating on the AST results on: * The exposure to carbapenems. * The total use of ICU and hospital resources and the cost-effectiveness. * The occurrence of other infections. * The colonization of the digestive tractus of patients with 3rd generation cephalosporins (3rdGC) resistant Gram-negative bacteria (GNB). In addition, an ancillary study will be performed (only in participating centers from the Ile de France region) to compare : * The composition of the intestinal microbiota among patients with an early de-escalation guided by the betaLACTA® test results and a standard de-escalation on AST results at 48-72h. * The evolution of intestinal microbiota of patients after exposure to different beta-lactam antibiotics, from carbapenems or cefepim/ceftazidim during the empirical treatment, to the definitive beta-lactam antibiotic chosen to cure the infection after antibiotic susceptibility test results. * The outcomes of ICU patients (mortality at D90, occurrence of infection, ICU length of stay, etc.) according to the composition of their intestinal microbiota and to its evolution during antibiotic treatment. To meet these objectives, 646 patients will be enrolled.