Prevalent PCR ribotypes and antibiotic sensitivity of clinical isolates of clostridium difficile

ABSTRACT

C.difficile is an important cause of nosocomial diarrhoea and pseudomembranous colitis [PMC], has a mortality rate that ranges from 15 to 30%. Therefore, in this study we investigated the incidence rate, toxigenicity and susceptibility pattern of C.difficile isolates to anti-anaerobic agents. We have also investigated the genotypes of clinical isolates by PCR ribotyping. The study was conducted on 80 patients [40 diarrhoeic and 40 non diarrhoeic] who had history of antibiotic exposure in the previous four weeks as well as on 20 healthy control subjects. The overall incidence rate of C.difficile was 35%. None of the healthy controls had positive culture. Analysis of the cytotoxin producing C.difficile strains showed that 40% of symptomatic and 20% of asymptomatic patients were infected by the cytotoxigenic strains [p<0.05]. A total of 35 C.difficile isolates were investigated for their susceptibility to 15 antibiotics using the E test. Amoxycillin/clavulanic acid, ampicillin, meropenem, metronidazole, penicillin, piperacillin, piperacillin/tazobactam, teicoplanin and vancomycin had excellent activity against all isolates of C.difficile. Multiple resistance to two or more antibiotics was observed in toxigenic, more than the non-toxigenic strains [ratio, 2.751] and in symptomatic than the asymptomatic patients [ratio, 2.5 1]. Interestingly, the 35 C.difficile culture positive patients harboured 10 different, highly diverse PCR ribotypes. Ribotypes 097 [23%] and 078 [17%] were the most prevalent toxigenic ribotypes responsible for over one-third of the cases of C.difficile associated diarrhoea [CDAD] seen. In conclusion, we believe that the extent of C.difficile involvement in diarrhoeal diseases would be better judged by direct comparison with the isolation rates of other enteric pathogens in antibioticassociated diarrhoea. In addition, our finding suggest that metronidazole should remain the drug of choice for the therapy of CDAD. It is also concluded that the prevalent PCR ribotypes of C.difficile strains isolated in our study are different from those found in Europe