ANTIMICROBIAL RESISTANCE, VIRULENCE AND GENOTYPIC PROFILING OF Clostridium difficile ISOLATED FROM ANIMALS AND HUMANS
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Date
2024-02
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SRI VENKATESWARA VETERINARY UNIVERSITY, TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The 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.