The revolving door between hospital and community: extended-spectrum beta-lactamase-producing Escherichia coli in Dublin.

BACKGROUND: Escherichia coli that produce extended-spectrum beta-lactamases (ESBLs) are an increasing cause of healthcare-associated infection, and community healthcare facilities may be a reservoir for important epidemic clones.

AIM: To characterize retrospectively and investigate the epidemiology of ESBL-producing E. coli collected in a Dublin hospital, during 2009 and 2010, and to investigate the dissemination of specific clones within hospital and community healthcare facilities.

METHODS: Pulsed-field gel electrophoresis (PFGE) was used to determine the genetic relatedness of 100 ESBL-producing E. coli isolates. Phylogenetic groups were determined and the O25b-ST131 clone identified in the collection. The genetic data were correlated with antimicrobial susceptibility, clinical and demographic data to explore the epidemiology of specific clones.

FINDINGS: Phylogenetic groups B2 (62%) and D (18%) were the most common and were associated with non-urinary isolates (P<0.0001 by Fisher's exact test). PFGE revealed 12 clusters (≥ 80% similarity), the largest of which clustered with the epidemic UK strain A. Residents of long-term care facilities (LTCFs) in the community exclusively carried the O25b-ST131 clone and phylogenetic groups B2 and D.

CONCLUSIONS: E. coli O25b-ST131 is largely responsible for ESBL-producing E. coli in LTCFs in Dublin. The distribution of ESBL-producing E. coli in our hospital and community highlights a 'revolving door' through which these resistant bacteria spread and disseminate.