Characterization of clostridium difficile isolated from diarrheal patients in a tertiary-care hospital, Karnataka, South India

Increase in Clostridium difficile infection in tertiary-care hospitals in Karnataka, South India with a paucity of data on antibiotic susceptibility and genetic characteristics of the pathogen from this region of the country necessitated this study. From April 2012 to December 2014, 480 hospitalized antibiotic-associated diarrhea cases with a history of antibiotic treatment in the previous three weeks were enrolled. Sixteen percent of the samples were positive for C. difficile toxins A and B by rapid enzyme immunoassay, anaerobic culture and multiplex PCR. In 40 representative strains, minimum inhibitory concentrations (MICs) determined by E-test revealed that 39 strains were resistant to imipenem and moxifloxacin (MIC > 32 µg/ml), 38 to clindamycin (MIC > 256 µg/ml) and 19 to tetracycline (MIC > 4 µg/ml), while all 40 strains were susceptible to ampicillin (MIC < 2 µg/ml), ampicillin sulbactam (MIC < 8 µg/ml), metronidazole (MIC < 8 µg/ml) and vancomycin group (MIC < 2 µg/ml). Pulsed field gel-electrophoresis (PFGE) of 13 representative strains grouped them into three clusters: cluster A consisting of two strains having > 65% similarity, cluster B of 6 strains with 100% similarity (considered clonal) and 3 strains with > 85% similarity, and cluster C of 2 strains with 50% similarity. Clusters A and C contained unrelated strains having different antibiograms. Periodic monitoring of resistance profiles with epidemiological typing by PFGE should aid in interpretation of emerging drug resistant C. difficile clones.