Department of Veterinary Medicine, COVS, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India.
College Central Laboratory, COVS, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India.
PLoS One. 2022 May 3;17(5):e0264762. doi: 10.1371/journal.pone.0264762. eCollection 2022.
Staphylococcus aureus (S. aureus) is the most prevalent microorganism associated with mastitis in cattle, which harbours several virulence factors and antibiotic resistance genes. The present study aimed to characterize S. aureus isolated from mastitic milk of the cattle for antibiotic resistance (blaZ and mecA), haemolysins (hla and hlb) and enterotoxins (sea, seb, sec, and sed) genes. A total of 69 staphylococci were isolated and phenotypically characterized for haemolytic properties on 5% sheep blood agar medium. Out of 69 isolates, 55 (79.71%) were identified as S. aureus by polymerase chain reaction assay. Among S. aureus, the majority of the isolates harboured the gene blaZ (92.73%), followed by coa (89.09%), hlb (60%) and hla (49.09%). Gene mecA responsible for methicillin resistance was detected in 23.64% of S. aureus isolates. Enterotoxin genes seb (9.09%), sec (1.82%) and sed (7.27%) responsible for food poisoning were detected at a comparatively lower rate and none of the S. aureus strain was found positive for sea. Additionally, antimicrobial susceptibility study of S. aureus against 18 antimicrobial discs showed maximum resistance to oxytetracycline, penicillin, and fluoroquinolone groups, contrarily, we observed maximum sensitivity to methicillin and cefuroxime antimicrobials. The high occurrence rate of S. aureus harbouring genes for virulence factors and antimicrobial resistance needs appropriate strategies to control the pathogen spread to the human population.
金黄色葡萄球菌（S. aureus）是引起奶牛乳腺炎最常见的微生物，它携带多种毒力因子和抗生素耐药基因。本研究旨在对从奶牛乳腺炎乳中分离的金黄色葡萄球菌进行抗生素耐药（blaZ 和 mecA）、溶血素（hla 和 hlb）和肠毒素（sea、seb、sec 和 sed）基因特征分析。共分离了 69 株葡萄球菌，并在 5%绵羊血琼脂培养基上对其溶血特性进行了表型特征分析。在 69 株分离株中，55 株（79.71%）通过聚合酶链反应检测鉴定为金黄色葡萄球菌。在金黄色葡萄球菌中，携带 blaZ 基因的分离株最多（92.73%），其次是 coa（89.09%）、hlb（60%）和 hla（49.09%）。检测到 mecA 基因可导致耐甲氧西林，其阳性率为 23.64%。seb（9.09%）、sec（1.82%）和 sed（7.27%）等肠毒素基因负责食物中毒，检出率相对较低，且未发现金黄色葡萄球菌菌株携带 sea 基因。此外，金黄色葡萄球菌对 18 种抗菌药物药敏纸片的药敏试验显示，对氧四环素、青霉素和氟喹诺酮类药物的耐药率最高，而对甲氧西林和头孢呋辛的耐药率最低。金黄色葡萄球菌携带毒力因子和抗生素耐药基因的发生率较高，需要采取适当的策略来控制病原体向人群传播。
