胸腺嘧啶依赖型金黄色葡萄球菌小菌落突变株的分离鉴定

本试验对由患慢性奶牛乳房炎奶样中分离出的1株疑似金黄色葡萄球菌小菌落突变株(SCVs)进行形态观察、金黄色葡萄球菌相关保守基因片段(nuc、nucA、16S rDNA) 多重PCR扩增鉴定、药敏试验、生理生化特性研究及补偿试验。结果显示分离出1株金黄色葡萄球菌SCVs,该菌含有金黄色葡萄球菌菌种特异性基因nuc和nucA;与金黄色葡萄球菌质控菌株ATCC 25923的抑菌圈大小明显不同;菌落形态主要表现为菌落细小、生长缓慢、溶血能力下降;凝固酶活性下降;耐盐能力降低;革兰氏染色为革兰氏阳性球菌,呈葡萄状排列;补偿试验鉴定该金黄色葡萄球菌SCVs为胸腺嘧啶依赖型。结果表明成功分离鉴定出1株胸腺嘧啶依赖型金黄色葡萄球菌SCVs,为由金黄色葡萄球菌SCVs引起的奶牛慢性乳房炎的预防和控制及其致病机制的研究奠定前期基础。

Isolation and Identification of Thymine-dependent Staphylococcus aureus Small Colony Variant

We observed the bacterial colony morphology;conducted multiple PCR amplification for the gene (nuc,nucA,16S rDNA);researched the physiological and biochemical characteristics of a isolate of Staphylococcus aureus small colony variant (S.aureus SCVs) from milk samples of dairy cow mastitis;and investigated its antibiotic resistance and auxotroph type. The isolate from milk samples of dairy cow mastitis was identified as S.aureus SCVs with the gene (nuc,nucA,16S rDNA) confirmed by multiple PCR amplification. Compared with the standard strain ATCC 25923,it had different antibiotic resistances. Its major phenotypes included small colony,slow growth,decreased hemolysis,decreased coagulase,decreased salt tolerance ability. This clinical isolate of gram positive bacteria in grape like clusters,and complementation test showed that the growth of this clone was thymine-dependent.One thymine-dependent S.aureus SCV was isolated and identified,a series of biochemical tests were conducted,which laid the groundwork for the control and prevention of the cow mastitis disease caused by S.aureus SCVs,and researches on its pathogenic mechanism.