Prevalence of toxin A-nonproducing/toxin-B-producing Clostridium difficile in the Tsukuba-Tsuchiura district, Japan

Abstract

In Japan, many clinical laboratories may not have recognized toxin A-nonproducing/toxin B-producing (A-/B+) Clostridium difficile, because rapid diagnostic kits detecting toxin B of C. difficile have not been available in the laboratories. Therefore, we examined the prevalence of A-/B+ strains in the Tsukuba-Tsuchiura district, Japan. Fecal specimens submitted for C. difficile toxin tests in four tertiary hospitals in the district were collected for 6 months. Several C. difficile A-/B+ strains, isolated in two nosocomial outbreaks that had occurred in geographically distant areas in Japan, were also simultaneously analyzed as controls. C. difficile was isolated from 159 of 332 specimens collected. Ten (6.3%) of the 159 C. difficile strains were A-/B+ strains. Nine A-/B+ strains, isolated in one hospital, had an identical genomic pattern by polymerase chain reaction (PCR) ribotyping and macrorestriction analysis with pulsed-field gel electrophoresis (PFGE). The A-/B+ strain isolated in another hospital and some of those in the geographically distant hospitals were indistinguishable from the nine strains by PCR ribotyping but were distinguishable with PFGE analysis. We concluded that A-/B+ strains are not epidemic in this district and that PFGE analysis may be preferable to PCR ribotyping for the genotyping of C. difficile A-/B+ strains. The reason why most of the A-/B+ strains were detected in the one hospital was unclear.