新生儿百日咳致病株抗菌药物敏感性和抗原基因型研究

Antimicrobial susceptibility and antigen genotypes of Bordetella pertussis strains isolated from neonates

摘要:

目的 探讨新生儿百日咳抗菌药物的可选方案，阐明致病株的抗原基因型。方法 以2013年5月至2018年7月分离到的32株新生儿百日咳鲍特菌为研究对象。采用E-test法检测红霉素、磺胺甲基异噁唑-甲氧苄啶（SMZ）、氨苄西林等共18种抗菌药物的最低抑菌浓度（MIC）；扩增分离株23S rRNA基因并测序，检测红霉素耐药基因的突变位点，分析菌株抗原相关的7个基因型（ptxA、ptxC、ptxP、prn、fim2、fim3和tcfA）。结果 25株（25/32，78%）百日咳鲍特菌对红霉素、阿奇霉素、克拉霉素、克林霉素的MIC值均>256 mg/L，且23S rRNA基因均有红霉素耐药A2047G突变。所有菌株对SMZ的MIC值均≤ 0.064 mg/L。氨苄西林、阿莫西林、阿莫西林‐克拉维酸和头孢曲松的MIC值波动在0.032~1 mg/L。大环内酯类耐药菌株的抗原基因型均为ptxA1/ptxC1/ptxP1/prn1/fim2-1/fim3-1/tcfA2。结论 新生儿百日咳鲍特菌对大环内酯类抗菌药物耐药常见，体外试验支持超说明书使用磺胺类抗菌药物是治疗大环内酯类耐药的新生儿百日咳的可靠方案。耐药菌流行更加强调了免疫预防的重要性。

Abstract:

Objective To investigate the alternative antimicrobial drugs for the treatment of neonatal pertussis and the antigen genotypes of Bordetella pertussis (B. pertussis) strains. Methods A total of 32 B. pertussis strains isolated from neonates between May 2013 and July 2018 were used in this study. E-test stripes were used to measure the minimal inhibitory concentration (MIC) of 18 antimicrobial drugs including erythromycin, sulfamethoxazole-trimethoprim (SMZ) and ampicillin. The 23S rRNA gene of isolated strains was amplifed and sequenced to identify the mutation site of erythromycin resistance gene, and the seven antigen genotypes of B. pertussis strains (ptxA, ptxC, ptxP, prn, fm2, fm3 and tcfA2) were analyzed. Results Of the 32 B. pertussis strains, 25 (78%) were resistant to erythromycin, azithromycin, clarithromycin and clindamycin, with an MIC of >256 mg/L, and A2047G mutation was observed in the 23S rRNA gene. All strains had an MIC of ≤ 0.064 mg/L for SMZ. The MIC of ampicillin, amoxicillin, amoxicillinclavulanic acid and ceftriaxone ranged from 0.032 to 1 mg/L. The strains resistant to macrolide antibiotics had an antigen genotype of ptxA1/ptxC1/ptxP1/prn1/fm2-1/fm3-1/tcfA2. Conclusions B. pertussis strains from neonates are often resistant to macrolides, and the in vitro test shows that off-label use of sulfonamides is a reliable regimen for the treatment of neonates with macrolide-resistant pertussis. The prevalence of drug-resistant strains further emphasizes the importance of immunoprophylaxis.