中文摘要：

目的分离鉴定变异链球菌临床分离株。方法收集高龋患者和无龋健康人口腔中牙菌斑标本进行厌氧培养，通过细菌形态学观察、生物化学鉴定、自动微生物分析系统分析、聚合酶链反应（PCR）扩增变异链球菌基因的特异性片段表面蛋白抗原Ⅰ／Ⅱ（spaP）、葡糖基转移酶B（gtfB）和葡聚糖酶（dexA）以及基因分型等方法对获得的变异链球菌临床分离株进行鉴定。结果从32例临床受试者口腔中分离获得46株变异链球菌临床分离株，经生物化学，自动微生物分析系统，变异链球菌的特异性基因spaP、gtfS和dexA的PCR扩增均鉴定为变异链球菌，基因分型发现其中5株临床分离株的基因型与其他菌株相同。结论获得41株不同基因型变异链球菌临床分离株。

英文摘要：

Objective To identify Streptococcus mutans （S. mutans） strains from clinical samples. Methods Plaque samples from caries-active and caries-free sites on enamel surfaces were obtained and cultivated for S. mutans isolation. Morphology, biochemistry, automatic microorganism analysis system and polymerase chain reaction using primers homo- logous to surface protein antigen I/II （spaP）, glucosyhransferase B （gtfB） and dextranase （dexA） were used to identify S. mutans. Genotype of isolated S. mutans was determined by arbitrarily primed polymerase chain reaction. Results Forty-six strains of S. mutans were obtained from the 32 subjects and were identified as S. mutans by biochemistry, automatic microorganism analysis system and polymerase chain reaction. Five identical genotypes were found by arbi- trarily primed polymerase chain reaction. Conclusion Forty-one strains of S. mutans with different genotype were obtained from clinical samples.