M olecular detection of antibiotic resistance genes and virulence genes in Staphylococcus spp. isolated from goat milkmilk
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Date
2019
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Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana
Abstract
Antimicrobial resistance is the phenomenon in which the microorganisms become resistant to the effects of drugs, that are used to cure the infections caused by them. The present study was conducted for determination of antibiotic resistance patterns and for detection of antibiotic resistance genes and virulence genes in Staphylococcus spp. isolated from goat milk. A total of 200 milk samples were collected from mastitic (n=136) as well as healthy goats (n=64) and processed for isolation of Staphylococcus spp. Out of these samples, 136 samples (68%) were positive by Sodium Lauryl Sulphate (SLS) test. Out of 200 samples, 47 isolates of Staphylococcus spp. were isolated and identified by biochemical tests. Out of 47 isolates, 33 isolates were coagulase positive Staphylococcus spp. and 14 isolates were found to be coagulase negative. All the isolates were screened for their antimicrobial activity using culture sensitivity test against 17 antibiotics which revealed highest resistance to penicillin G followed by oxacillin, methicillin and vancomycin. All the 47 isolates were confirmed by genus specific PCR and an amplicon size of 532 bp was obtained. PCR was conducted for detection of antibiotic resistance genes and virulence genes among the isolates. The presence of tetK gene encoding the tetracycline efflux pump was found to be highest (89.3%), followed by blaZ gene encoding for β-lactamase resistance (87.23%), mecA gene encoding for methicillin resistance (48.93%) and tetM gene encoding for tetracycline resistance protein (14.89%). Among the virulence genes, the presence of eno gene which encodes for enolase was found to be highest (87.23%) followed by hlg gene which encodes for gamma-haemolysin (17.02%) in the isolates. No isolate was positive for cna gene which encodes for collagen adhesin. Statistical analysis using chi-square test, revealed that a highly significant correlation was found between phenotypic and genotypic resistance in case of methicillin, oxacillin and penicillin resistance.
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