E. coli ST131 CTX-M-27 in French children

The recent emergence and diffusion of Escherichia coli isolates belonging to the multidrug-resistant and CTX-M-27-producing ST131 C1-M27 cluster, notably in the community, makes this cluster potentially as epidemic as the worldwide E coli ST131 subclade C2 composed of multidrug resistant isolates producing CTX-M-15. Whole genome of 35 extended-spectrum beta-lactamase (ESBL) producing ST131 isolates identified within a cohort of 1885 French children followed over a 5 year-period was sequenced to characterize the ST131 E. coli isolates producing CTX-M-27 recently emerged in France. Multivariate analysis was performed to assess risk factors of children fecal carriage of CTX-M-27-producing isolates. ST131 isolates producing CTX-M-27 (n=17), particularly those belonging to C1-M27 cluster (n=14), harbored many resistance-encoding genes and mostly a F1:A2:B20 plasmid type. In the multivariate analysis, having been hospitalized since birth (OR=10.9; 95%CI=2.4;48.8; p=0.002) and being cared for in a day-care center (OR=9.4;95%; CI=1.5;59.0; p=0.017) were independent risk factors for ST131 CTX-M-27 fecal carriage compared with ESBL-producing non-ST131 isolates. No independent risk factor was found when comparing CTX-M-15 (n=11) or CTX-M-1/14 (n=7)-producing ST131 isolates with ESBL-producing non-ST131 isolates or with non-ESBL-producing isolates. Several factors may contribute to the increase in fecal carriage of CTX-M-27-producing E. coli isolates: resistances to multiple antibiotics, capacity of the CTX-M-27 enzyme to hydrolyze both cefotaxime and ceftazidime, carriage of a peculiar F-type plasmid, and/or capacity to colonize children having been hospitalized since birth or attending day-care centers.