SRINIVASA RAO, T(MAJOR)BINDU KIRANMAYI, Ch.LAKSHMI KAVITHA, KSRINIVAS, K2019-07-092019-07-092018-12http://krishikosh.egranth.ac.in/handle/1/5810113380THESESCampylobacter is a well established food-borne zoonotic pathogen having a worldwide public health importance. The present study was undertaken to characterize Campylobacter species of animal and human origin based on cultural isolation. A total of 513 samples comprising faecal samples of livestock and poultry (174), intestinal contents of livestock and poultry (96), foods of animal origin (185) and human diarrhoeic samples (35) as well as samples of miscellaneous origin (23) were examined. Overall prevalence of Campylobacter spp. was found to be 4.87% (25/513) with highest prevalence in poultry intestinal samples (8/36, 22.2%), followed by pig intestinal contents (4/40, 10%), pig faecal samples (5/60, 8.33%), pork samples (3/90, 3.33%), human diarrhoeic samples (1/35, 2.85%), poultry faecal samples (3/114, 2.63%) and chicken meat samples (1/50, 2%). All 7 virulence genes under the study (iam, virB11, flaA, cadF, cdtA, cdtB, cdtC) were detectable. flaA and cadF genes were present in all the isolates (25/25, 100%) followed by iam (23/25, 92%), cdtA (20/25, 80%), cdtB (20/25, 80%), cdtC (17/25, 68%) and virB11 (4/25, 16%). Antibiogram profiling of 25 isolates revealed that a major fraction of the Campylobacter isolates showed sensitivity to colistin and co-trimoxazole (64%), chloramphenicol and azithromycin (56%) and ceftazidime (52%). All the Campylobacter isolates were resistant to at least one of the antibiotics tested. Higher resistance was observed for vancomycin and tetracycline (76%), cephalothin and ciprofloxacin (68%), erythromycin (56%) and doxycycline (52%). Notable percentages of isolates were intermediately resistant against nalidixic acid and nitrofurantoin (44%), gentamicin and streptomycin (32%) and clindamycin (28%). Resistance to β-lactam antibiotics like aztreonam (40%), cefotaxime (32%), ceftriaxone (40%) and ceftazidime (28%) were detected. ESBL production was confirmed phenotypically in 12 isolates by CDM . blaTEM was the only β-lactamase gene detected in 60% of the isolates. rep-PCR (ERIC-PCR and REP-PCR) and flaA-PCR-RFLP analysis revealed a greater degree of molecular heterogeneity among Campylobacter isolates from different sources. ERIC-PCR genotyping revealed 6 and 18 genotypes distinguished among 6 and 19 isolates of C. jejuni and C. coli, respectively. REP-PCR genotyping revealed 5 and 19 genotypes among 6 and 19 isolates of C. jejuni and C. coli., respectively while flaA PCR-RFLP typing of 6 isolates of C. jejuni and 19 C. coli isolates revealed 5 and 15 genotypes, respectively. The discriminatory power of the three typing methods for Campylobacter species were found to be highly significant (>0.90) i.e. 0.9967 (ERIC PCR and REP-PCR) and 0.9833 (flaA-PCR-RFLP). Cluster analysis revealed a great deal of homogeneity and heterogeneity among different isolates recovered from various sources and hinted at the chance of cross-contamination of foods of animal origin.ennullThesis