艰难梭菌克隆分布及药物敏感性现状分析

Clone distribution and antimicrobial susceptibility of Clostridium difficile isolates

目的探讨杭州地区医院获得性腹泻患者艰难梭菌的克隆分布及药敏表型特征。方法对2013年1月-2016年12月间浙江大学医学院附属第一医院及邵逸夫医院医院获得性腹泻患者的粪便标本进行艰难梭菌(Clostridium difficile,CD)培养初筛,初筛阳性菌株通过PCR扩增及测序分析16-23SrRNA基因及毒素基因(tcdA及tcdB基因),以明确CD菌种以及是否为产毒菌株;以MLST技术对产毒CD菌株进行同源性分析;并对CD菌株进行药敏敏感性试验。结果共培养CD菌株61株,其中54株为产毒菌株,tcdA及tcdB基因阳性菌株数分别为1株(A+B-)和53株(A-B+),未发现毒素基因双阳性菌株;产毒菌株来源于11个不同ST型别,其中7个ST型别为已知的;各ST型别间亲缘关系较远,ST54型别是最主要流行克隆型别占38.9%(21/54),其次是ST2、ST35和ST37,各占比13.0%(7/54);万古霉素及甲硝唑为敏感性最高的药物,未发现耐药菌株,其次是左氧氟沙星、四环素和环丙沙星,耐药率分别为16.6%、31.4%和38.8%,克林霉素及夫西地酸耐药率最高均为96.3%。结论毒素表型A-B+的ST54型艰难梭菌为本地区主要流行克隆,万古霉素和甲硝唑是有效的治疗CDI的抗菌药物。

OBJECTIVE To investigate the clone distribution and the antimicrobial susceptibility of the Clostridium difficile strains isolated from the patients diagnosed with hospital-acquired diarrhea in Hangzhou.METHODS Stool samples were collected from the patients who were diagnosed with hospital-acquired diarrhea and hospitalized the First Affiliated Hospital and Sir Run Run Shaw hospital,School of Medicine,Zhejiang University from Jan2013 to Dec 2016,the C.difficile strains were cultured and screened,Species identification and toxin detection were then carried out by using PCR followed by sequencing on the target genes of 16-23 SrRNA gene and toxin genes（tcdAand tcdB）,respectively.The homology of toxin-producing strains was analyzed by means of MLST,and the drug susceptibility testing was performed for the C.difficile strains.RESULTS Of totally 61 strains of C.difficile cultured,54 were positive for toxin genes,there were 1 strain（A＋B-）positive for tcdA and 53 strains（A-B＋）positive for tcdB;no strain harbored both tcdAand tcdB genes.Eleven different STs were identified among 54 toxin strains,7 of which were reported previously.ST54 was the most popular epidemic clone type（38.9%,21/54）,followed by ST2,ST35 and ST37（13%,7/54）.The result of drug susceptiblity testing showed that vancomycin and metronidazole remained the most sensitive antibiotics,the drug resistance rates to levofloxacin,tetracycline and ciprofloxacin were 16.6%,31.4% and 38.8%,respectively,and the drug resistance rates to clindamycin and fusiacid were the highest（96.3%）.CONCLUSION The ST54 type C.difficile strains that are positive for toxin phenotype A-B＋ are the predominant clone type in the district.Vancomycin and metronidazole remain the most effective antibiotics for treatment of C.difficile infection.