Hospital toilets and drainage systems as a reservoir for a long-term polyclonal outbreak of clinical infections with multidrug-resistant Klebsiella oxytoca species complex

The study investigated an increase in bacteraemia with extended-spectrum β-lactamase-producing Klebsiella oxytoca at a hospital in 2021, revealing an environmental source. Clinical K. oxytoca isolates were collected from patients and samples from sinks, shower drains, and toilet water. Whole-genome sequencing revealed four clusters and a polyclonal population of ESBL-producing K. oxytoca and Klebsiella michiganensis. Environmental sampling revealed widespread contamination, with toilet water being the most common source.