中国西北地区新疆省奶牛源金黄色葡萄球菌的耐药性、毒力基因谱和分子分型。
Antimicrobial resistance, virulence gene profile and molecular typing of Staphylococcus aureus isolates from dairy cows in Xinjiang Province, northwest China.
机构信息
College of Animal Science and Technology, Shihezi University, North Street No. 4, Shihezi, Xinjiang 832003, China.
College of Animal Science and Technology, Shihezi University, North Street No. 4, Shihezi, Xinjiang 832003, China.
出版信息
J Glob Antimicrob Resist. 2019 Mar;16:98-104. doi: 10.1016/j.jgar.2018.08.024. Epub 2018 Sep 10.
OBJECTIVES
Staphylococcus aureus (SA) is a major pathogen causing dairy cow mastitis and endometritis. Recently, animal-derived SA strains pose a serious public-health threat. However, little is known about antimicrobial resistance and virulence factors of SA isolated from dairy cows in Xinjiang, China. In this study, antimicrobial resistance, virulence gene profiles and genotypes of SA from clinical mastitis and endometritis in dairy cows were investigated.
METHODS
A total of 337 clinical samples (186 milk samples from clinical mastitis cases and 151 endometritis swab samples) were collected from 15 large-scale dairy farms and were screened for SA. All SA isolates were subjected to antimicrobial susceptibility testing, detection of virulence genes and molecular typing.
RESULTS
A total of 155 SA strains were isolated; 22 (14.2%) were methicillin-resistant S. aureus (MRSA). Resistance of MRSA isolates was significantly higher than that of methicillin-susceptible S. aureus (MSSA). The percentage of virulence genes varied between MSSA and MRSA. The strains could be divided into two SCCmec types (I and IVa), three agr types (I, II and III) and four spa types (t779, t2883, t13751 and t1939). MLST identified 14 sequence types, among which ST1 and ST9 had relatively high detection rates.
CONCLUSIONS
These findings revealed that ST9-t1939-agrI was the main genotype of MSSA, whilst ST1-SCCmecI-t1939-agrI was the main genotype of MRSA from dairy cows. More significantly, a novel ST (STX) was identified for the first time. The majority of SA strains from dairy cows were multidrug-resistant and carried multiple virulence genes, posing a potential public-health risk.
目的
金黄色葡萄球菌（SA）是引起奶牛乳腺炎和子宫内膜炎的主要病原体。最近，动物源性 SA 菌株对公共卫生构成了严重威胁。然而，目前对于中国新疆奶牛中分离的 SA 的抗菌药物耐药性和毒力因子知之甚少。本研究调查了奶牛临床乳腺炎和子宫内膜炎中 SA 的抗菌药物耐药性、毒力基因谱和基因型。
方法
从 15 个大型奶牛场采集了 337 份临床样本（186 份乳腺炎病例的牛奶样本和 151 份子宫内膜拭子样本），用于筛选 SA。所有 SA 分离株均进行抗菌药物敏感性试验、毒力基因检测和分子分型。
结果
共分离出 155 株 SA，其中 22 株（14.2%）为耐甲氧西林金黄色葡萄球菌（MRSA）。MRSA 分离株的耐药率明显高于甲氧西林敏感金黄色葡萄球菌（MSSA）。MSSA 和 MRSA 之间的毒力基因存在差异。这些菌株可分为 2 种 SCCmec 型（I 型和 IVa 型）、3 种 agr 型（I 型、II 型和 III 型）和 4 种 spa 型（t779、t2883、t13751 和 t1939）。MLST 鉴定出 14 种序列型，其中 ST1 和 ST9 的检出率较高。
结论
这些发现表明，ST9-t1939-agrI 是 MSSA 的主要基因型，而 ST1-SCCmecI-t1939-agrI 是奶牛中 MRSA 的主要基因型。更重要的是，首次发现了一种新型 ST（STX）。奶牛中分离的 SA 菌株大多为多药耐药，携带多种毒力基因，对公共卫生构成潜在威胁。
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