Panahi Mitra, Saei Habib Dastmalchi
Department of Microbiology, Faculty of Veterinary Medicine, Urmia University, P.O. Box 1177, Urmia, Iran.
Department of Microbiology, Faculty of Veterinary Medicine, Urmia University, P.O. Box 1177, Urmia, Iran.
Comp Immunol Microbiol Infect Dis. 2019 Feb;62:19-24. doi: 10.1016/j.cimid.2018.11.014. Epub 2018 Nov 30.
The aims of the present study were to investigate the genetic diversity and methicillin resistance in S. aureus isolates recovered from mastitis-affected buffaloes. Five hundred seventy-eight milk samples were obtained from buffaloes with mastitis in three provinces, Iran. Ninety-one of the 578 tested samples contained S. aureus (15.74%), in two cases were methicillin resistant S. aureus (MRSA). Isolates were typed by spa typing, followed by MLST on some representative isolates and SCCmec typing for MRSA strains. The presence of genes encoding Panton-Valentine leukocidin (PVL) was also tested by PCR. Eight spa types were identified, with t3576 (n = 18), t7311 (n = 18) and t937 (n = 17) were the most common, followed by t304 (n = 11), t7308 (n = 9), t521 (n = 7), t267 (n = 6), and t527 (n = 5). MLST revealed four different sequence types (STs) including ST97 (related to t521 and t527 spa types), ST352 (related to t267), ST291 (related to t304 and t937) and ST522 (related to t7338, t7311 and t3576). Two MRSA were identified as t304-ST291-SCCmecIV and t7311-ST522-SCCmecIV. No PVL-positive S. aureus were found. A significant difference in geographical distribution of genotypes was observed, with some types being prevalent in all studied provinces (P < 0.001). The results demonstrated genetic diversity among the S. aureus strains involved in mastitis in buffaloes. This study also provides evidence of the presence of MRSA belonging to genotypes which have been earlier reported in human infections, emphasizing the need for their epidemiological monitoring.
本研究的目的是调查从患乳腺炎的水牛中分离出的金黄色葡萄球菌的遗传多样性和耐甲氧西林情况。从伊朗三个省份的患乳腺炎的水牛身上采集了578份牛奶样本。在578份检测样本中，有91份含有金黄色葡萄球菌（15.74%），其中2份为耐甲氧西林金黄色葡萄球菌（MRSA）。通过spa分型对分离株进行分型，随后对一些代表性分离株进行多位点序列分型（MLST），并对MRSA菌株进行葡萄球菌盒式染色体 mec（SCCmec）分型。还通过聚合酶链反应（PCR）检测了编码杀白细胞素（PVL）的基因的存在情况。鉴定出8种spa型，其中t3576（n = 18）、t7311（n = 18）和t937（n = 17）最为常见，其次是t304（n = 11）、t7308（n = 9）、t521（n = 7）、t267（n = 6）和t527（n = 5）。MLST揭示了四种不同的序列类型（STs），包括ST97（与t521和t527 spa型相关）、ST352（与t267相关）、ST291（与t304和t937相关）和ST522（与t7338、t7311和t3576相关）。两株MRSA被鉴定为t304-ST291-SCCmecIV和t7311-ST522-SCCmecIV。未发现PVL阳性的金黄色葡萄球菌。观察到基因型的地理分布存在显著差异，某些类型在所有研究省份都很普遍（P < 0.001）。结果表明参与水牛乳腺炎的金黄色葡萄球菌菌株之间存在遗传多样性。本研究还提供了属于在人类感染中较早报道的基因型的MRSA存在的证据，强调了对其进行流行病学监测的必要性。
