Multilocus sequence typing and CTX-M characterization of ESBL-producing E. coli: a prospective single-centre study in Lower Saxony, Germany.

The increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacteria is a serious threat for current healthcare settings. In this study we investigated the molecular epidemiology of ESBL-producing E. coli at the University Medical Center Göttingen in Lower Saxony, Germany. All E. coli isolates with an ESBL phenotype were collected during a 6-month period in 2014. Multilocus sequence typing and CTX-M characterization were performed on 160 isolates. Of the ESBL-producing isolates 95·6% were CTX-M positive. Compared to recent Germany-wide studies, we found CTX-M-1 to occur in higher frequency than CTX-M-15 (44·4% vs. 34·4%). CTX-M-14 and CTX-M-27 were detected at 9·4% and 5·0%, respectively. The globally dominant sequence type (ST) 131, which is often associated with CTX-M-15, occurred at a relatively low rate of 24%. Major non-ST131 sequence types were ST101 (5%), ST58 (5%), ST10 (4·4%), ST38 (4·4%), ST410 (3·8%) and ST453 (3·1%). Several of these major sequence types were previously shown to be associated with livestock farming. Together, our study indicates that E. coli lineage distribution in individual healthcare settings can significantly differ from average numbers obtained in nationwide studies.