Molecular epidemiology and resistance profiles of Clostridium difficile in a tertiary care hospital in Spain

Epidemiological surveillance of Clostridium difficile infection has gained importance in recent years as a result of the rapid spread of epidemic strains, including hypervirulent strains and strains with reduced susceptibility to antimicrobials. The molecular epidemiology and antimicrobial susceptibility of C. difficile in the reference hospital of the Balearic Islands (Spain) is reported in this study. One hundred isolates of toxigenic C. difficile from different patients were selected using rapid dual EIA screening test. All isolates were characterized through toxin profile, PCR ribotyping and, in addition, multi-locus sequence typing (MLST) was performed on fifty selected strains. MICs to metronidazole, vancomycin, erythromycin and moxifloxacin were also determined. A total of 43 different ribotypes were distinguished, with higher prevalence of ribotype 014 (34%). Twenty one per cent of the isolates expressed binary toxin and it is noteworthy that 62% of these were identified as the hypervirulent ribotype 078, the second most prevalent ribotype found in our hospital (13%). A total of 20 different sequence types (STs) were found, including a new described allele and ST. MLST data showed a clear concordance between some ribotypes and STs, mainly represented by ribotype 014/ST-2, ribotype 078/ST-11 and ribotype 001/ST-3. Phylogenetic analysis also revealed that most of the isolates were genetically related, forming a large clonal complex. Finally, ribotypes 078 (ST-11) and 001 (ST-3) were associated with higher resistance to erythromycin and to erythromycin and moxifloxacin, respectively. All these data suggest that the combination of ribotyping and MLST is a good tool for the surveillance of the changing epidemiology of C. difficile. A wide dissemination of clones has been observed in our setting, ribotype 014 (ST-2) being the most prevalent followed by the hypervirulent ribotype 078 (ST-11) and ribotype 001 (ST-3), their spread in our setting probably influenced by their higher resistance.