牛源金黄色葡萄球菌耐药性与相关耐药基因和菌株毒力基因的相关性研究

Study on relationship between resistance and resistance-and virulencerelated genes in Staphylococcus ɑureus from bovine mastitis cases

分别采用纸片扩散法和PCR检测了牛源金黄色葡萄球菌对红霉素和四环素的耐药性与相关耐药基因和毒力基因,进而分析了耐药性与相关耐药基因和毒力基因之间的相关性。结果表明,37株金黄色葡萄球菌菌株中,红霉素耐药菌株占27%,而含有红霉素耐药基因ermB或ermC的菌株占19%,其中30%的红霉素耐药表型菌株含有ermB或ermC,所有菌株均未检测到ermA;四环素耐药菌株占22%,而含有四环素耐药基因tet K的菌株占27%,其中75%的四环素表型耐药菌株含有tetK,所有菌株均未检测到tetM。金黄色葡萄球菌毒力基因lukED、hlb、hla、hld、edin、tst和lukPV的检出率分别为89%、73%、70%、70%、14%、5%和3%,未检测到eta、etb和lukM基因。统计学分析结果表明,金黄色葡萄球菌的红霉素耐药表型与相关耐药基因之间未发现相关性,而与毒力基因tst和lukED的相关性较强;金黄色葡萄球菌四环素耐药表型与耐药基因tetK存在相关性,而未发现四环素耐药表型与菌株毒力基因之间存在相关性。结果提示,金黄色葡萄球菌对红霉素和四环素的耐药率较高;耐药基因并不能作为菌株表型耐药的诊断指标,但其潜在的危险应当引起关注;此外,金黄色葡萄球菌菌株中高频率的毒力基因lukED、hla、hlb和hld编码的毒力因子白细胞毒素和溶血素是引发奶牛乳腺炎的主要因素。

The erythromycin and tetracycline resistance were determined by disk diffusion method,andresistance-and virulence-related genes were detected by PCR to analyze the relationship between the resistance and resistance-and virulence-related genes in Staphylococcus aureus isolated from bovine mastitis cases. The results showed that,in 37 S.aureus strains,27%were resistant to erythromycin.erm B or erm C were detected in 19% isolates and found in 30% of erythromycin-resistant isolates. None isolate carried erm A was detected. Meanwhile, 22 % of S.aureus isolates were resistant to tetracycline. And 27% isolates carried tet K, which was detected in 75% tetracycline-resistant strains.tet M was not found in any isolates. Virulence genes luk ED, hlb, hla, hld, edin, tst and luk PV were detected in 89%, 73%, 70%, 70%, 14%, 5% and 3% of S.aureus isolates, respectively.eta,etb and luk M genes were not found in any isolates. The erythromycin resistance and virulence genes tst and luk ED showed high relationship.In addition,the relationship between resistance and resistance gene tet K was detected. These results indicated that S.aureus exhibited high resistance rates to erythromycin and tetracycline. Although resistance genes can not be used as a diagnostic indicator for phenotypic antimicrobial susceptibility patterns, their potential threat should draw public attention. In addition,leukotoxins and hemolysins encoded by frequent virulence genes luk ED, hla, hlb and hld played a crucial role in pathogenesis of bovine mastitis.