摘要
目的 探讨恩诺沙星对鼠疫耶尔森菌(简称鼠疫菌)L型的诱导作用,以期了解更多鼠疫菌L型的形成条件和生物学特性.方法 将鼠疫菌EV株分别接种于含0、0.5、5、10、50、100、500、1 000ng/mL恩诺沙星的赫氏培养基中培养.将含50ng/mL恩诺沙星的培养物接种于不含恩诺沙星的赫氏培养基中进行返祖培养.观察各样品菌落形态,通过革兰染色和细胞壁染色观察细菌形态,透射电镜观察细胞壁状态.对鼠疫菌EV株和鼠疫菌L型进行16S rDNA鉴定,并进行同源性分析及构建系统发育树.结果 赫氏培养基中含0.5ng/mL恩诺沙星可引起鼠疫菌形态改变,由典型短杆菌变为长杆菌.恩诺沙星浓度为50 ng/mL时鼠疫菌细胞壁缺失,细菌无法正常分裂增殖而呈长杆状,盘绕成团,菌落呈油煎蛋样.恩诺沙星诱导鼠疫菌L型在正常赫氏培养基中可返祖,并表现为短小杆状的典型鼠疫菌形态.16S rDNA鉴定诱导菌与诱导前亲本EV株同源性为100％.结论 恩诺沙星可诱导鼠疫菌形成L型.
Abstract
Objective To investigate the induction of L-forms of Yersiniapestis by enrofloxacin,in order to know more about the formation conditions and biological characteristics of L-form Yersinia pestis.Methods Yersinia pestis EV were cultured in Hiss agar media containing 0,0.5,5,10,50,100,500 and 1 000 ng/mL enrofloxacin respectively.The cultures containing 50 ng/mL enrofloxacin was subcultured in Hiss agar media without enrofloxacin for reversion.The colonial morphology of each sample was observed.The bacterial morphology was observed by Gram staining and cell wall staining,while the cell wall integrity by transmission electron microscope.Yersinia pestis EV and L-form Yersinia pestis were identified by 16S rDNA,analyzed for the homology and the phylogenetic tree were constructed.Results Enrofloxacin 0.5 ng/mL contained in Hiss agar media caused morphological changes of Yersinia pestis,from typical short-rod to long-rod shape.When the concentration of enrofloxacin was 50 ng/mL,the cell wall of Yersinia pestis was deficient,and the bacteria could not divide and proliferate normally,but showed long-rod shape and coiled into a mass,with the colonial morphology like fried eggs.Enrofloxacin-induced L-form Yersinia pestis reversed in normal Hiss agar media,and displayed a typical Yersinia pestis short-rod shape.16S rDNA identification showed that the homology between the induced strain and the parent EV strain before induction was 100％.Conclusion Enrofloxacin can induce the L-forms of Yersinia pestis.
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