Molecular typing of methicillin resistant Staphylococcus aureus (MRSA) from livestock and farm environmental samples
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Date
2021
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Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana
Abstract
The 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.