Correlation between serogroup and susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline among 308 isolates of Clostridium difficile.

The susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline of 308 isolates of Clostridium difficile from various origins was determined by a disc diffusion susceptibility testing and the results were compared with the serogroup of the strains. For the five antimicrobials, there was a clear-cut separation between susceptible and resistant strains. Some correlation between resistance and serogroup was found. Almost all of the 161 isolates of serogroups A, F, G, H and X were susceptible to all antibiotics. The 32 toxigenic isolates of serogroup C were characterized by a typical resistance pattern which could be used for typing purposes. Other serogroups showed variable patterns. The review of 64 cases of antibiotic associated diarrhoea showed that these differences in susceptibility could have clinical implications: all seven cases due to clindamycin were caused by a clindamycin resistant strain of serogroup C, whereas cases associated with other antibiotics were distributed among various serogroups.