Venugopal Nimita, Mitra Susweta, Tewari Rituparna, Ganaie Feroze, Shome Rajeswari, Rahman Habibur, Shome Bibek R
ICAR-National Institute of Veterinary Epidemiology and Disease Informatics, Bengaluru, Karnataka, India.
Department of Microbiology, Jain University, Bengaluru, Karnataka, India.
Vet World. 2019 Nov;12(11):1760-1768. doi: 10.14202/vetworld.2019.1760-1768. Epub 2019 Nov 11.
Methicillin-resistant staphylococci are among the emerging pathogens which have become a threat to both human and animal health. The present investigation intended to examine the occurrence and the molecular characteristics of methicillin-resistant (MRSA) and methicillin-resistant coagulase-negative staphylococci (MRCoNS) recovered from cattle, its handlers, and their environment.
A total of 666 specimens were subjected to culture method and genus-specific polymerase chain reaction (PCR) for the identification of . Methicillin resistance was substantiated by PCR identification of A and C resistance determinants. Species-specific identification of A positive isolates was conducted by multiplex PCR. The unidentified species were deciphered by 16S rRNA gene sequencing approach. The A positive isolates were further characterized by staphylococcal cassette chromosome (SCC) typing and multilocus sequence typing (MLST).
Duplex PCR identified 728 isolates, of which 66 (9%) were positive for A gene. MRSA constituted 24% of the total A positive isolates. Among MRCoNS, (42%), and (11%) were the most common species identified. Overall, 47% of the A positive isolates belonged to SCC type V. MLST analysis showed eight different sequence types (STs) among MRSA isolates of which five were novel STs. Among methicillin-resistant , 19 different STs were found, of which nine novel STs were detected.
The increase in the prevalence of A positive staphylococci, especially MRCoNS in cattle is a great concern in view of their transmission potential. Hence, continuous monitoring and molecular characterization of methicillin-resistant staphylococci should be elucidated in human and animal sectors so as to prevent the spread of these resistant pathogens.
耐甲氧西林葡萄球菌是新出现的病原体之一，已对人类和动物健康构成威胁。本研究旨在检测从牛、其饲养者及其环境中分离出的耐甲氧西林金黄色葡萄球菌（MRSA）和耐甲氧西林凝固酶阴性葡萄球菌（MRCoNS）的发生率及分子特征。
共666份标本采用培养法和属特异性聚合酶链反应（PCR）进行鉴定。通过PCR鉴定A和C耐药决定簇来证实甲氧西林耐药性。对A阳性分离株进行多重PCR进行种特异性鉴定。未鉴定出的菌种通过16S rRNA基因测序方法进行解析。对A阳性分离株进一步通过葡萄球菌盒式染色体（SCC）分型和多位点序列分型（MLST）进行特征分析。
双重PCR鉴定出728株葡萄球菌，其中66株（9%）A基因呈阳性。MRSA占A阳性分离株总数的24%。在MRCoNS中，鉴定出的最常见菌种为（42%）和（11%）。总体而言，47%的A阳性分离株属于SCC V型。MLST分析显示，MRSA分离株中有8种不同的序列类型（STs），其中5种为新的STs。在耐甲氧西林的中，发现了19种不同的STs，其中9种为新的STs。
鉴于A阳性葡萄球菌，尤其是牛体内的MRCoNS的传播潜力，其患病率的增加令人高度关注。因此，应在人类和动物领域阐明耐甲氧西林葡萄球菌的持续监测和分子特征，以防止这些耐药病原体的传播。
