Putative transmission of extended-spectrum β-lactamase-producing Escherichia coli among men who have sex with men in Amsterdam, the Netherlands.

Objectives: A previous study showed higher prevalence of Escherichia coli (E. coli) expressing extended-spectrum β-lactamases (ESBL-Ec) among men who have sex with men (MSM) in Amsterdam, the Netherlands, compared with the general Dutch population. This study genetically characterised the ESBL-Ec isolates and investigated whether the increased prevalence could be explained by transmission between participants.