Molecular characterization and antimicrobial phenotypes in clinical isolates of Clostridium difficile in a tertiary care hospital, Mallorca

Abstract number: P1460

Déniz C., Riera E., Pérez J.L., Oliver A., Mena A.

Objectives: There have been some changes in the epidemiology of the Clostridium difficile infection, mainly represented by the rapid spread of epidemic strains, including hypervirulent strain known as ribotype 027. In order to know the epidemiology of our hospital environment we performed molecular characterization and antimicrobial phenotypes of toxigenic C. difficile clinical isolates collected from August 2007 to August 2009, at the major public hospital of the island of Mallorca, Spain.

Methods: A total of 70 clinical isolates of C. difficile obtained from different patients with diarrhoea during 2 years were studied. Rapid ELISA detection of toxins A and B (Wampole^®, Inverness medical), directly from the stools or from the culture, were performed for all the isolates. Molecular toxigenic profile of the strains was studied by PCR amplification of the tcdA (toxin A), tcdB (toxin B) and cdtA, cdtB (binary toxin) regions. Typing and clonal relation was studied by PCR ribotyping through amplification of the 16S-23S rRNA. C. difficile ribotypes 001, 078 and 027 were used as controls. Isolates with PCR ribotypes patterns different from those control strains were classified by letters. Finally, antimicrobial susceptibility patterns to metronidazole (MTR), vancomycin (VAN), clindamycin (CLIN), erythromycin (ERY) and moxifloxacin (MXF) were studied by determining the MIC using the Etest method.

Results: 96% of the isolates were toxigenic by PCR and 3 isolates were false positives ELISA results. All toxigenic isolates produced toxins A and B and 27% of the isolates also produced binary toxin. We found 30 different PCR ribotype patterns. The most prevalent ribotypes were A ribotype (A+B+, 21%), 078 ribotype (A+B+bin+, 19%), B ribotype (A+B+, 13%) and 001 ribotype (A+B+, 9%). All strains were susceptible to MTR and VAN, but resistance to CLIN, ERY and MXF was found in 61%, 23% and 23%, respectively. We also observed almost 100% CLIN resistance and 50% ERY resistance in ribotypes 078 and 001 and 50% MOXI resistance in ribotype 001.

Conclusion: The first epidemiological study of C. difficile in our hospital shows the presence of heterogeneous ribotyping population with binary toxin-producing strains, mainly represented by the hypervirulent ribotype 078. We found no clear association between antimicrobial profiles and ribotyping. Finally, there is no evidence of occurrence of clusters in our hospital or presence of the 027 epidemic ribotype and A-B+ strains.