Person-to-person transmission of microbes in a nursing home serving patients in a persistent vegetative state

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Background: A probable outbreak of respiratory disease in a nursing home serving exclusively patients in a persistent vegetative state (PVS) resulted in hospitalization of eight patients. Methods: Microbes from all PVS patients’ respiratory tracks and environments were surveyed by microbiological methods. Major pathogenic microbes were analyzed by pulsed-field gel electrophoresis (PFGE). Results: 24 PVS patients were investigated. Half were colonized with at least four different pathogenic microbes in their respiratory tracts. The most prevalent microbes were Pseudomonas aeruginosa in 15 patients (62.5%), Serratia marcescens in 14 (58.3%), Citrobacter koseri in nine (37.5%), Streptococcus pneumoniae in six (25%), and Proteus mirabilis in five (20.8%). By PFGE analysis, one major pulsotype each was identified for S. marcescens (92.9%, 13/14) and S. pneumoniae (100%, 6/6), whereas diverse pulsotypes were identified for P. aeruginosa, C. koseri, and P. mirabilis. Both major pulsotypes for S. marcescens and S. pneumoniae were also found in strains from patients outside the nursing home. No environmental reservoir was found for prevalent microbes. Conclusions: Clonal transmission of S. marcescens and S. pneumoniae among PVS patients in the nursing home was evident, indicating a need to enforce control measures to reduce threats to this type of facility.