Molecular epidemiology and susceptibility profiles of Clostridium difficile in New Zealand, 2009

The aim of this study was to provide baseline information on the molecular epidemiology and the antimicrobial susceptibility of Clostridium difficile (C. difficile) clinical isolates from patients throughout New Zealand.

Faecal specimens that were C. difficile-toxin positive by EIA assay were cultured for C. difficile. Antimicrobial susceptibility testing was carried out using the agar dilution minimum inhibitory concentration method. The following antibiotics were tested: penicillin, piperacillin/tazobactam, vancomycin, ciprofloxacin, moxifloxacin, clindamycin, clarithromycin, meropenem and metronidazole. Molecular typing by PCR-ribotyping was performed on all isolates.

C. difficile was isolated from 108 of 159 submitted faecal specimens. After excluding the repeats, there were 101 isolates from 97 patients. Most isolates were fully susceptible to the range of antibiotics tested. Thirty-two PCR-ribotypes were identified among the 101 isolates. The most common ribotypes were 014 (18 isolates), 002 (11) and 005 (10). No PCR-ribotype 027 isolates were identified, but one isolate of another hypervirulent strain, PCR-ribotype 078, was identified.

There is a wide range of C. difficile PCR-ribotypes circulating in New Zealand and antimicrobial resistance is uncommon. Ongoing surveillance for hypervirulent strains of C. difficile is essential to prevent the dissemination of these strains within New Zealand hospitals.