Faculty of Veterinary Medicine, Department of Production Animal Medicine, University of Helsinki, Koetilantie 7, 00014 Helsinki, Finland.
Acta Vet Scand. 2013 Aug 28;55(1):61. doi: 10.1186/1751-0147-55-61.
Methicillin-resistant staphylococci (MRS) are increasingly being isolated in bovine mastitis. The aim of our study was to evaluate the occurrence of MRS in Finnish mastitis milk samples and characterize the MRS isolates using molecular methods.
Methicillin-resistant S. aureus (MRSA) was a rare finding in bovine mastitis in Finland. Only two out of 135 (1.5%) S. aureus isolates were positive for mec genes. One of these carried mecA and was of spa type t172, SCCmec type IV and ST375, and the other harboured mecC, being spa type t3256, and ST130. MRSA ST375 is common among human MRSA isolates in Finland, but this is the first report in the country of bovine mecC MRSA. In coagulase-negative staphylococci (CoNS) originating from bovine mastitis, methicillin resistance was more common. In the two CoNS collections studied, 5.2% (17/324) and 1.8% (2/110) of the isolates were mecA positive. Eighteen of these were methicillin-resistant S. epidermidis (MRSE), which were divided into 6 separate PFGE clusters. One pulsotype was detected in different parts of the country, indicating clonal spread. Most MRSE (13/18) were of SCCmec type IV, one was of type V and four were non-typeable. Comparison with a human staphylococcal database indicated that bovine MRSE strains were not closely related to human MRSE isolates.
The occurrence of MRS, especially MRSA, in bovine mastitis in Finland was low. Most methicillin-resistant bovine CoNS are MRSE, and we found evidence of a bovine MRSE strain that may spread clonally. This is the first report of a Finnish bovine isolate of MRSAmecC ST130. The study provides a baseline for further MRS monitoring.
耐甲氧西林葡萄球菌（MRS）在奶牛乳腺炎中越来越多地被分离出来。我们的研究目的是评估芬兰乳腺炎奶样中 MRS 的发生情况，并使用分子方法对 MRS 分离株进行特征描述。
耐甲氧西林金黄色葡萄球菌（MRSA）在芬兰奶牛乳腺炎中是一种罕见的发现。在 135 株金黄色葡萄球菌分离株中，仅有 2 株（1.5%）携带 mec 基因。其中一株携带 mecA，spa 型为 t172，SCCmec 型为 IV 型和 ST375，另一株携带 mecC，spa 型为 t3256，ST130。MRSA ST375 在芬兰的人源 MRSA 分离株中很常见，但这是该国首例奶牛 mecC-MRSA 的报道。在来自奶牛乳腺炎的凝固酶阴性葡萄球菌（CoNS）中，耐甲氧西林更为常见。在研究的两个 CoNS 集合中，5.2%（17/324）和 1.8%（2/110）的分离株 mecA 阳性。其中 18 株为耐甲氧西林表皮葡萄球菌（MRSE），分为 6 个独立的 PFGE 簇。在该国不同地区检测到 1 个脉冲型，表明存在克隆传播。大多数 MRSE（13/18）为 SCCmec 型 IV，1 型为 V 型，4 型为不可分型。与人类葡萄球菌数据库比较表明，牛源 MRSE 菌株与人类 MRSE 分离株没有密切关系。
耐甲氧西林葡萄球菌，尤其是 MRSA，在芬兰奶牛乳腺炎中的发生率较低。大多数耐甲氧西林的牛源 CoNS 是 MRSE，我们发现了可能发生克隆传播的牛源 MRSE 菌株的证据。这是芬兰首例牛源耐甲氧西林金黄色葡萄球菌 mecC ST130 的报告。该研究为进一步的 MRS 监测提供了基线。
