Molecular epidemiology, plasmid analysis, virulence, and resistance of Escherichia coli isolated from neonatal intensive care units in Poland.

We investigated the set of Escherichia coli isolates originating from newborns in relation to resistance, virulence factors (VFs), phylogenetic groups, plasmid replicon typing, and genotypes. The most isolates were clustered in ECOR group B2. Extended-spectrum beta-lactamase phenotype was found in 27.7% of isolates. The ST131 clone was detected among 33 strains, 12 of which carried the CTX-M-15 gene. Most VFs were detected among ST131 isolates and in the B2 group. IbeA gene was found more frequently in the blood isolates, while the iha gene, in the urine isolates. The 3 most prevalent replicon types were IncFIB, IncF, and IncFIA.