SRINIVASA RAO .T (MAJOR)BINDU KIRANMAYI .CHSUDHA RANI CHOWDARY .CHNAGARJUNA REDDY NAKKA2024-07-072024-07-072024-02https://krishikosh.egranth.ac.in/handle/1/5810211559The present study was undertaken for isolation and characterization of Clostridium difficile from food animals, foods of animal origin, environmental samples and human samples. Out of 400 samples analyzed, 15% (60/400) were positive for C. difficile by cultural isolation and confirmation by biochemical tests. Out of 60 phenotypically positive isolates from different sources, 11 (18.33%) isolates were further confirmed by species specific PCR targeting genes (tpi and gluD genes) The highest rate of occurrence of C. difficile was obtained in chicken samples 8.0% (4/50), while lowest in mutton samples 2% (1/50). All the C. difficile isolates (100%) showed gelatinase activity, 45.45% isolates exhibited congo red binding activity, none of the isolates were positive for lecithinase activity on on egg yolk agar. Eight C. difficile isolates (72.72%) carried both toxin A and toxin B, two (18.18%) isolates carried only toxin B, 10 (90.91%) isolates carried binary toxin and one (9.09%) isolate from diarrhoeic stools of vety students did not carry any of the toxins. Among 11 C. difficile isolates higher resistance was observed towards pencillin G and linezolid (100% each), followed by gentamicin (81.81%), cefotaxime and clindamycin (72.72% each) and ciprofloxacin (63.63%). The highest sensitivity was observed for chloramphenicol (100%) followed by metronidazole and vancomycin (81.81% each), moxifloxacin (72.72%) and meropenem (54.54%). Intermediate resistance pattern were observed against ceftriaxone and tetracycline (18.18% each). All the C. difficile isolates were MDR and MAR indexing of all isolates yielded 6 MAR index groups. Out of 11 C. difficile isolates nine were identified as ESBL suspects by PST and ESBL production was confirmed in nine (81.81%) isolates by CDM and in eight (72.72%) isolates by DDST. All the 9 phenotypic ESBL suspects did not carry any of the beta lactamase genes (blaTEM, blaSHV and blaOXA) by multiplex PCR. Among 11 C. difficile isolates, three (27.27%) isolates carried tetM genes, two (18.18%) isolates carried vanC1 gene and none of the isolates carried aac-aph genes by PCR. A greater degree of heterogeneity was observed among 11 C. difficile isolates from different sources by REP-PCR. Genotyping of C. difficile by REP-PCR was highly significant since the discriminatory power is one. Cluster analysis also revealed a greater degree of homogeneity and heterogeneity among different isolates recovered from different sources.EnglishThesis