为了解奶牛场乳房炎金黄色葡萄球菌(Staphylococcus aureus,S.aureus)的耐药性,并对耐甲氧西林金黄色葡萄球菌(MRSA)的耐药基因进行研究,本研究采集奶牛场临床型乳房炎奶样89份进行金黄色葡萄球菌分离鉴定及药敏试验,采用K-B法检测其对常用13种抗生素的敏感性;利用双重PCR扩增MRSA的nuc基因和mecA耐药基因;应用基因外重复回文序列(repetitive extragenic palindromic elements,REP)PCR对分离菌株进行基因多样性分析.结果显示,共分离到16株MRSA;在监测的13种药物中,耐药率超过50％的达到10种,其中对头孢曲松(CRO)、头孢噻肟(CTX)、环丙沙星(CIP)和亚胺培南(IPM)耐药率高达93.75％(15/16),但未见对头孢呃酮(SCF)耐药的分离菌株;耐药基因检测结果显示,16株菌中都携带有mecA耐药基因,除1株外其他15株分离菌都携带特异致病nuc基因.REP-PCR把分离菌株分为13种基因型(A-M),同源性≥90％的只有6株菌.研究结果表明,奶牛乳房炎金黄葡萄球菌的多重耐药比较严重,分子多样性复杂,mecA是其耐甲氧西林类药物的重要机制,本研究为MRSA耐药菌的有效检测及奶牛乳房炎的治疗提供了科学依据.%The purpose of this study is to understand the drug resistance of S.aureus within a dairy farm and study mecA resistant genes of MRSA.Totally 89 samples were Collected from the dairy dominant mastitis milk samples were employed for separation and identification of S.aureus,as well as the drug susceptibility test. K-B method was used to detect the sensitivity of 13 kinds of antibiotics,nuc gene and mecA resistance gene of MRSA amplified by duplex PCR. The repetitive extragenic palindromic elements, PCR, REP-PCR method was applied to analyze gene diversity of S. aureus isolated.We were isolated from 16 MRSA strains, in the detection of the 13 drugs, the drug resistance rate of 10 kinds was more than 50％, the drug resistance rates of CRO, CTX, CIP, and IPM were as high as 93.75％ (15/16), but there was no isolated strain of SCF resistance. The results of drug resistance gene detection showed that 16 strains were carrying pathogenic gene nuc, 15 strains were all carrying the mecA resistance gene in addition to the 1 strain.the separated strains were divided into 13 genotypes (A-M)using REP-PCR, homology of only 6 strains was over 90％. The research results showed that the multi drug resistance of S.aureus for cow mastitis was very serious and molecular diversity complex, mecA was an important mechanism in methicillin-resistant drug,provided scientific guidance for the treatment of cow mastitis and effective detection of MRSA.
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