A retrospective study of the epidemiology of Clostridium difficile infection at a University Hospital in Japan: genotypic features of the isolates and clinical characteristics of the patients

Clostridium difficile is a major cause of antibiotic-associated diarrhea and frequently results in healthcare-associated infections. The epidemiology of C. difficile infection (CDI), including the prevalent polymerase chain reaction (PCR) ribotypes and the clinical characteristics of the patients, is not well known in Japan, compared to the situation in the United States and Europe. We performed PCR ribotyping of C. difficile isolates from 71 consecutive patients with CDI at a University Hospital over a 3-year period and investigated the clinical features of those patients. CDI was diagnosed when a patient with diarrhea or colitis was found to have toxin B-positive C. difficile with no other enteropathogenic microorganisms. Toxin A-positive, toxin B-positive, binary toxin-positive (A⁺B⁺CDT⁺) strains; toxin A-positive, toxin B-positive, binary toxin-negative (A⁺B⁺CDT⁻) strains; and toxin A-negative, toxin B-positive, binary toxin-negative (A⁻B⁺CDT⁻) strains were isolated from 4, 58, and 9 patients, respectively, indicating that infections with binary toxin-positive strains were uncommon (5.6%). PCR ribotyping of the isolates demonstrated that among the 71 strains, 20 different PCR ribotypes were identified and that types smz, yok, and hr were predominant (19, 14, and 13 isolates, respectively), all of which were A⁺B⁺CDT⁻. No specific time periods or wards were found to be associated with the three types; PCR ribotyping analysis clearly showed that the three types spread almost evenly in all wards for the 3 years studied. Comparative analysis of the clinical characteristics of patients harboring the three C. difficile types indicated that the duration of CDI was longer in the yok group than in the hr group. PCR ribotyping, which is easy to perform, appears to give us useful information to trace CDI cases in clinical settings. Further, the analysis of a large number of CDI cases may allow evaluation of the possible relationship between specific C. difficile types and the clinical features of patients.