Foodborne nosocomial outbreak of SHV1 and CTX-M-15-producing Klebsiella pneumoniae: epidemiology and control.

BACKGROUND: We describe a foodborne nosocomial outbreak due to extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae.

METHODS: An outbreak of ESBL K. pneumoniae was detected in March 2008. Initial control measures included contact isolation and a protocol for routine detection and reinforcement in hand hygiene practices. ESBL producers were screened for the bla(TEM), bla(SHV), and bla(CTX-M) genes. Pulsed-field gel electrophoresis analysis was performed using XbaI as a restriction endonuclease.

RESULTS: One hundred fifty-six colonized and/or infected patients were identified, 35 (22.4%) of whom had infection. The outbreak affected all hospital wards. Fecal carriage was up to 38% of patients in some wards. Of note, investigation revealed a very short delay between admission and colonization. None of the health care workers or environmental surfaces in the wards was found to be colonized. This prompted an epidemiological investigation of a possible foodborne transmission. We found that up to 35% of the hospital kitchen-screened surfaces or foodstuff were colonized and that 6 (14%) of 44 food handlers were found to be fecal carriers. Phenotypic and genotypic analysis of all clinical, environmental, and fecal carrier isolates showed the dissemination of a single strain of SHV-1 and CTX-M-15-producing K. pneumoniae. At that time, structural and functional reforms in the kitchen were performed. These were followed by a progressive reduction in colonization and infection rates among inpatients until complete control was obtained in December 2008. No restrictions in the use of antibiotics were needed.

CONCLUSIONS: To our knowledge, this is the first reported hospital outbreak that provides evidence that food can be a transmission vector for ESBL K. pneumoniae.