Rai, Tejinder SinghShilpa B.2022-01-052022-01-052021https://krishikosh.egranth.ac.in/handle/1/5810180400The present study was taken up to investigate the prevalence of MRSA together with AMR genes among apparently healthy animals and their molecular typing. A total of 407 samples including skin swabs (130), nasal swabs (85), vaginal swabs (60), milk samples (35) and farm environmental samples (97) were collected from cattle, buffalo, sheep and pigs and their farm environment. A total of 76 (18.6%) Staphylococcus aureus isolates were obtained that further yielded 12 (2.94%) MRSA isolates on molecular detection of mecA gene. Highest number (7/12) of MRSA isolates were obtained from pigs followed by cattle (4/12) and only one was found from sheep. No MRSA could be isolated from buffalo. On Culture Sensitivity Test, the isolates showed resistance in decreasing order to Penicillin-G (94.7%), Methicillin (72.3%), Ampicillin (57.8%), Tetracycline (52.63%), Cefoxitin (30.26%), Doxycycline hydrochloride (28.94%) and Amikacin (22%). The isolates showed low resistance to Chloramphenicol (10.5%), Cefazolin (7.8%) and Ceftriaxone (6.57%) and least (3.94%) each to Cefotaxime and Co-Trimoxazole. The highest prevalence of AMR genes among S. aureus isolates in the decreasing order was as follows: tetK (76.3%), tetM (42%), blaZ (32.8%), aacA-aphD (31%). The AMR genes harboured among 12 MRSA isolates were tetK (11), tetM (8), ermC (2), ermB (4), aacAaphD (7), blaZ (6) and blaTEM (5). On SCCmec typing, 2 isolates were identified as Type III, 1 isolate as Type IVa and 1 isolate as Type V. On spa typing, 8 MRSA isolates could be sequenced and the different spa types obtained were t7286, t091, t448 and t442. Novel sequences of the spa gene were obtained in 3 isolates. This study indicated that AMR was high in livestock animals and their premises as shown both by phenotypic and genotypic detection of AMR genes in Staphylococcus aureus and MRSA. Hence it can colonize among healthy livestock and vice versa leading to alarming threat of antimicrobial resistance.EnglishThesis