a1 Department of Bacteriology, National Institute of Infectious Diseases, Tokyo, Japan
a2 Clinical and Research Laboratory, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan
a3 Department of Infectious Diseases, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan
a4 Department of Virology, Tokyo Medical and Dental University, Tokyo, Japan
a5 AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan
To investigate two clusters of diarrhoea cases observed in our geriatric hospital wards, the faecal specimens were analysed. Reversed passive latex agglutination assay revealed that 63·2% and 41·7% of the faecal specimens from each cluster were positive for Clostridium perfringens enterotoxin. PCR assay revealed that 71·4% and 68·8% of C. perfringens isolates from each cluster were positive for the enterotoxin gene (cpe). These observations suggested that both the clusters were outbreaks caused by enterotoxigenic C. perfringens. Subsequent pulsed-field gel electrophoresis analysis revealed that the two outbreaks were caused by different C. perfringens isolates. However, these outbreak isolates as well as other sporadic diarrhoea isolates shared a 75-kb plasmid on which the cpe gene and the tcp locus were located. The 75-kb plasmid had horizontally spread to various C. perfringens isolates and had caused outbreaks and sporadic infections. However, the site and time of the plasmid transfer are unclear.
(Accepted April 11 2008)
(Online publication May 19 2008)