阿奇霉素耐药淋球菌菌株的耐药机制分析和分子流行病学特征

摘要

目的 探讨阿奇霉素耐药淋球菌菌株的分子流行病学特征,分析耐阿奇霉素淋球菌的耐药机制.方法 对36株耐阿奇霉素淋球菌[最小抑菌浓度(MIC)≥1 mg/L]的核糖体23SrRNA、mtrR基因及核糖体蛋白L4/L22基因进行PCR扩增测序分析,寻找可能的突变位点,比较耐药基因突变在中度耐药组(MIC 1~64 mg/L)和高度耐药组(MIC ≥256 mg/L)间的差异.采用NG-MAST对基因序列进行分型,获得阿奇霉素耐药菌株的基因型别及分布特征.结果 高度耐药淋球菌菌株核糖体23SrRNA的4个等位基因均有A2143G的突变,中度耐药菌株中有3株(8 mg/L≤MIC≤32 mg/L)核糖体23SrRNA 4个等位基因为C2599T突变.36株阿奇霉素耐药菌株中鉴定出28个不同的序列型别(ST),其中16个为新发现的ST,2个未分型.结论 淋球菌核糖体23SrRNA基因不同位点突变可能与阿奇霉素不同程度的耐药相关,A2143G突变可能导致高度耐药,C2599T可能与中度耐药有关,mtrR基因G45D的突变可能参与阿奇霉素耐药.通过NG-MAST分型显示阿奇耐药菌株的基因型具有多样性,且覆盖范围也较为广泛;经过系统进化树推断por581基因型有较大可能影响阿奇霉素高度耐药.%Objective To investigate molecular epidemiological characteristics of azithromycin-resistant Neisseria gonorrhoeae strains, and analyze the resistance mechanism of azithromycin-resistant strains.Methods In order to detect mutated alleles and compare high-level azithromycin resistance group(MIC≥256 mg/L) with moderate azithromycin resistance group(1 mg/L≤MIC≤64 mg/L), PCR was performed to amplify the 23SrRNA and mtrR genes of all the 36 azithromycin-resistant strains.Sequence types(STs) and distribution characteristics of the strains were obtained by the method of NG-MAST.Results All the isolates with high-level azithromycin resistance contained mutation A2143G in all 4 alleles of 23SrRNA, and three of moderately resistant isolates(8 mg/L≤MIC≤32 mg/L) contained mutation C2599T in 4 alleles of 23SrRNA.Among 36 azithromycin-resistant isolates, 28 STs were identified by NG-MAST, of which 16 STs were novel and 2 were nontypeable.Conclusion Different mutated alleles of 23SrRNA gene in Neisseria gonorrhoeae may be related with different levels of azithromycin resistance.A2143G mutation may lead to high-level resistance, C2599T mutation may be related with moderate resistance and G45D mutation may contribute to azithromycin resistance.Moreover, genotypes of azithromycin-resistant isolates in this area have high diversity and wide range, indicating that por581 is likely associated with high resistance to azithromycin via phylogenetic analysis.