健康婴儿体内的无毒脆弱拟杆菌的分离及鉴定

Isolation and identification of a non-enterotoxigenic strain of Bacteroides fragilis from a healthy term infant

目的 对分离到的1株无毒脆弱拟杆菌进行鉴定.方法 2012年7月从健康足月新生儿的粪便中分离得到1株脆弱拟杆菌,观察其形态特征、培养特征,并进行生理生化鉴定、药敏试验及16s rRNA序列测定和分析.急慢性毒性试验检测毒性.结果 分离得到的菌株在细菌形态、培养特性、生理生化反应结果与脆弱拟杆菌相似.经BLASTN序列比对,所分离菌株与脆弱拟杆菌标准株NCTC9343同源性达99％.药敏实验提示,新分离菌株对头孢拉定、阿莫西林、庆大霉素、磺胺甲噁唑、甲氧苄啶不敏感,急慢性毒性试验提示无毒性.结论 分离的细菌为1株无毒的脆弱拟杆菌.

Objective To identify a non-enterotoxigenic strain of Bacteroidesfragilis.Methods B.fragilis was isolated from the feces of a healthy full-term infant in July 2012 and identified by morphological characteristics and culture conditions,physiological and biochemical test,drug sensitivity test,16 s rRNA gene sequencing and short and long-term toxicity tests.Results The isolated bacterial strain was similar to B.fragilis in terms of morphological characteristics,culture conditions and physiological and biochemical features.The results of 16s rRNA gene sequencing demonstrated that the nucleoids of newly-isolated strain were up to 99％ identical to those of standard stain of B.fragilis NCTC9343 （GenBank）.The drug sensitivity test revealed that it was not sensitive to cefradine,amoxicillin,gentamicin,sulfamethoxazole and trimethoprim.And the acute and long-term toxicity tests were negative.Conclusion The isolated bacteria is a non-enterotoxigenic strain of B.fragilis.