An outbreak of ST307 extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in a rehabilitation center: An unusual source and route of transmission

Objective: Nosocomial outbreaks due to multidrug-resistant microorganisms in rehabilitation centers have rarely been reported. We report an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (ESBL-K. pneumoniae) on a single ward in a rehabilitation center in Rotterdam, The Netherlands. Design: Outbreak description. Setting: A 40-bed ward of a rehabilitation center in the Netherlands. Methods: In October 2016, 2 patients were found to be colonized by genetically indistinguishable ESBL-K. pneumoniae isolates. Therefore, an outbreak management team was installed, by whom a contact tracing plan was made. In addition to general outbreak measures, specific measures were formulated to allow continuation of the rehabilitation process. Also, environmental cultures were taken. Multiple-locus variable-number tandem-repeat analysis and amplification fragment-length polymorphism were used to determine strain relatedness. Selected isolates were subjected to whole-genome multilocus sequence typing. Results: The outbreak lasted 8 weeks. In total, 14 patients were colonized with an ESBL-K. pneumoniae, of whom 11 patients had an isolate belonging to sequence type 307. Overall, 163 environmental cultures were taken. Several sites of a household washing machine were repeatedly found to be contaminated with the outbreak strain. This machine was used to wash lifting slings and patient clothing contaminated with feces. The outbreak was contained after taking the machine temporarily out of service and implementing a reinforced and adapted protocol on the use of this machine. Conclusion: We conclude that in this outbreak, the route of transmission of the outbreak strain via the household washing machine played a major role.