Investigation of an Enterobacter hormaechei OXA-436 carbapenemase outbreak: when everything goes down the drain

Summary: Over a time period of 18 months an Enterobacter hormaechei sequence type (ST) 90, harboring a blaOXA-436 carbapenemase gene, was isolated from seven patients at Odense University Hospital, Denmark. The patients were all from the same department, but there was no apparent direct epidemiological link. Whole genome sequencing (WGS) was performed on all clinical isolates as well as on a number of environmental samples including two E. hormaechei ST90 isolates carrying the blaOXA-436 gene, which were isolated in samples from two shower drains at the department. These drains were suspected to be the source of the outbreak.