百日咳鲍特菌对大环内酯类抗生素的耐药性、耐药相关分子特征及PFGE型别特征分析

Macrolide resistance,molecular characteristics and PFGE types of Bordetella pertussis strains

目的分析百日咳鲍特菌对大环内酯类抗生素的耐药性、耐药相关分子特征及脉冲场凝胶电泳分型(plused-field gel electrophoresis,PFGE)特征,了解百日咳菌株对大环内酯类抗生素可能的耐药机制,探讨PFGE基因型与耐药表型之间的关联性。方法采用E-test法检测2018—2020年临床分离百日咳鲍特菌对红霉素、阿奇霉素、克拉霉素的耐药性;PCR检测可水平转移的耐药基因与耐药相关突变位点;采用PFGE方法对菌株进行分型。结果共分离到35株百日咳鲍特菌菌株,其中27株对3种抗生素均耐药,2株对红霉素和阿奇霉素耐药,对克拉霉素敏感,6株对3种抗生素均敏感;部分耐药株携带甲基化酶基因ermA(27.6%,8/29)和ermB(31.0%,9/29),耐药株均检出A2047G位点突变,敏感株均未发现耐药基因和位点突变;耐药株PFGE分型为BpSR23和BpFINR9型,敏感株PFGE分型为其他型。结论临床分离百日咳鲍特菌对红霉素耐药严重,并且开始向大环内酯类其他抗生素蔓延,甲基化酶基因的获得及23S rRNA基因A2047G位点突变可能是其耐药的主要机制,PFGE基因型与耐药表型之间存在一定的关联性。

Objective To analysis the macrolide resistance,molecular characteristics and plused-field gel electrophoresis(PFGE)type of Bordetella pertussis(Bp),explore the possible resistance mechanism and the relationship between PFGE types and macrolide resistance profiles.Methods Erythromycin,azithromycin and clarithromycin susceptibility of clinical isolates during 2016 to 2018 was determined by E-test.PCR was used to detect the drug-resistant genes and mutation sites.PFGE were employed to do molecular typing for the strains.Results Thirty-five strains were isolated,of which 27 strains were resistant to all three antibiotics,two strains were resistant to erythromycin and azithromycin,and six strains were sensitive to all three antibiotics.Partial macrolide resistant strains carried the methylase gene ermA(27.6%,8/29)and ermB(31.0%,9/29);A2047G site mutation was detected in macrolide-resistant strains,while no drug-resistant genes or mutation sites were found in sensitive strains.Resistant strains were classified into BPSR23 and BPFINR9 types,while sensitive strains were other profiles.Conclusions The clinical isolated Bp were seriously resistant to erythromy and showed signs of resistance to other macrolides.The acquisition of methylase gene and mutation of A2047G site might be the main mechanism of resistance.The macrolide resistance might have has a certain correlation with PFGE profile.