奶牛源金黄色葡萄球菌临床分离株的耐药特性、生物膜及其相关基因分布研究

Antimicrobial Resistant Characteristics,Biofilm Formation and Analysis of Biofilm-associated Genes in Clinical Isolates of MRSA from Cow Mastitis

【目的】为了解引起奶牛乳房炎的金黄色葡萄球菌(SA)分离株的耐药性及其生物膜特性。【方法】本研究采用纸片扩散法对新疆地区奶牛源临床分离的164株SA的耐药特性进行检测,并对MRSA进行判定;用BHI培养24 h形成生物膜,结晶紫染色后测其吸光度(OD570 nm)值,比较分析MRSA和MSSA菌株间生物膜形成能力;对生物膜形成相关基因的分布进行检测。【结果】164株SA临床分离株中共检出22株MRSA,检出率为13.41%;SA对青霉素、头孢西丁、红霉素、甲氧苄啶、四环素耐药株较多;MRSA对头孢类、氟喹诺酮类和大环内酯类抗菌药物的耐药率明显高于甲氧西林敏感SA(MSSA);24 h时,MRSA和MSSA生物膜生成能力差异显著(P<0.05),MRSA菌株的生物膜生成能力显著高于MSSA菌株;MRSA菌株黏附素clf A、clf B、fnb B、Fib、cna、Fn BP基因携带率在54.55%~100%之间,显著高于MSSA菌株检出率(P<0.05)。【结论】呋喃妥因、替考拉宁、磷霉素可作为优选药用于治疗MRSA和β-内酰胺类耐药株引起的严重感染。MRSA菌株较于MSSA菌株具有较强的生物膜形成能力,这与MRSA的较强抗性具有相关性。

【Objective】The present paper was conducted to know the antimicrobial resistance and biofilm characteristics of Staphylococcus aureus（ SA） from cow mastitis.【Method】The drug resistance of 164 clinical S. aureu isolates was determined by using disk diffusion method in the present study. Then methicillin-resistant Staphylococcus aureus（ MRSA） strains were identified. MRSA and MSSA strains were cultured on BHI for 24 hours respectively,the optical density（ OD570 nm） was determined by using a mieroplate reader after staining with crystal violet,then formation capacity of biofilm between MRSA and MSSA strains were comparatively analyzed. The distribution of genes related to biofilm formation was also examined. 【Result】A total of 22 strains of MRSA have been detected among the 164 S. aureu sisolates,with the detection rate of 13. 41 %; To penicillin,cefoxitin,erythromycin,trimethoprim and tetracycline resistant strains of Staphylococcus aureus,the drug resistance rates of MRSA to cephalosporins,quinolones and macrolides antibiotics were significantly higher than those of the methicillin-sensitive Staphylococcus aureus（ MSSA）,respectively. At 24 hours,the biofilm formation ability of MRSA and MSSA was significantly different（ P 0. 05）,and the biofilm formation ability of MRSA strain was significantly higher than that of MSSA strain.The detection rates of adhesin clf A,clf B,fnb B,Fib,cna and Fn BP ranged from 54. 55 % to 100 %,respectively,while the detection rate of MRSA was higher than that of MSSA（ P 0.05）. 【Conclusion】Furantoin,teicoplanin and fosfomycin can be used as preferred drugs for the treatment of severe infections caused by MRSA and β-lactam resistant strains. The biofilm formation ability of MRSA strain was higher than that of MSSA strain,which is related to the strong resistance of MRSA.