Variability of intestinal colonization with third-generation cephalosporin-resistant Enterobacteriaceae and antibiotic use in intensive care units.

OBJECTIVES Healthcare-associated infections due to third-generation cephalosporin-resistant Enterobacteriaceae (CRE) have become a major public health threat, especially in intensive care units (ICUs). We assessed and compared β-lactam use, the prevalence of colonization with CRE at admission and the incidence of CRE acquisition across ICUs. PATIENTS AND METHODS A cohort study was conducted in 10 ICUs of the Paris (France) metropolitan area between November 2005 and February 2006. Antibiotic use was recorded prospectively in all patients admitted during the study period. Rectal swabs were collected at admission, twice weekly thereafter, before β-lactam prescription and before discharge. RESULTS A total of 893 patients provided 3453 rectal swabs; 793 of the patients were newly admitted, mostly for medical reasons (80.7%). On admission, 74 patients (9.6%) were colonized with CRE, including 32 with an extended-spectrum β-lactamase (ESBL)-producing strain. Among the remaining 694 naive patients, 94 acquired CRE during their follow-up, including 31 with an ESBL-producing strain. Incidence rates of colonization ranged from 8.8 to 21.0/1000 patient-days for all CRE, and from 1.4 to 10.9/1000 patient-days for ESBL producers. A majority of patients (68.3%) were prescribed β-lactams during their ICU stay, with defined daily doses ranging from 428 to 985/1000 patient-days. Across ICUs, prescriptions of all antibiotics, β-lactams and carbapenems were significantly correlated to incidence rates of colonization with ESBL-producing CRE. CONCLUSIONS The standardized and systematic follow-up of patients in 10 ICUs revealed great heterogeneity in the rates of colonization with ESBL- and non-ESBL-producing CRE, as well as in antimicrobial prescription practices.