化脓性链球菌耐药与毒力基因研究

目的调查一组70株化脓性链球菌耐药与毒力基因存在状况,以及菌株间的亲缘关系。方法70株化脓性链球菌分离自日照市中心医院2012—2017年急性扁桃体炎、急性咽炎患者的咽拭子标本。5种抗菌药物敏感性试验为Kirby-Bauer法。采用聚合酶链反应(PCR)及序列分析的方法分析8种耐药基因和3种毒力基因。检测结果作样本聚类分析(UPGMA法)。结果70株化脓性链球菌对青霉素、苯唑西林、万古霉素敏感性均达100.00%,对红霉素耐药率较高(94.29%)。青霉素耐药基因均为阴性,大环内醋类耐药基因检出ermB和mefA基因,其中ermB和mefA阳性66株(94.29%)。可移动遗传元件标志基因intTN916检出率高(94.29%)。3种毒力基因均有较高的检出率:spyA58株(82.86%)、sagj68株(97.14%)、也64株(91.43%)。样本聚类分析可见,70株化脓性链球菌分为A^N共14个分类单元,根据是否携带e/mS基因,可分为I、II二个群,I群9个分类单元均携带ermB基因,II群5个分类单元均不携带ermB基因。结论70株化脓性链球菌携带的大环内酯类耐药基因和ermB和mefA,以及可移动遗传元件标志基因是对红霉素产生耐药的重要原因。spyA、sagA、slo等3种毒力基因是化脓性链球菌常见的毒力基因,推测它们是化脓性链球菌感染导致感染灶局部炎症和坏死的原因。

Investigation of drug resistance determinants and virulence factors in Streptococcus pyogenes

Objective To investigate the distribution of resistant determinants and virulence factors in 70 Streptococcus pyogenes (S. pyogenes) and their phylogenetics. Methods From 2012 to 2017, 70 S. pyogenes were collected from throat swab specimens from patients with acute tonsillitis and acute pharyngitis in Rizhao Central Hospital. Antimicrobial susceptibility test of five kinds of antimicrobial agents were performed by the Kirby-Bauer method. Then, eight kinds of resistant determinants and two kinds of virulence factors were analyzed by PCR. Finally, resistant determinants were used as molecular markers to perform the sample cluster analysis (UPGMA). Results 70 S. pyogenes were susceptible to penicillin, oxacillin, and vancomycin, and had high resistant rate to erythromycin (94.29%). Resistant genes to penicillin were all negative, ermB and mefA were positive 66 strains (94.29%), which were resistant genes to macrolide. Positive rates of genetic markers of intTN916 were high (94.29%). Moreover, three virulent genes were positive: spyA in 58 strains (82.86%) of, sagA in 68 strains (97.14%), and slo in 64 strains (91.43%). The sample cluster analysis showed that 70 S. pyogenes could be divided into 14 operational taxonomic units (OTUs), and could be divided into two groups: Group I and II depending on ermB. The gene ermB was positive in nine OTUsin group I, while ermB was negative in five OTUs in group II. Conclusion Resistant determinants against mrolide, ermB and mefA, as well as genetic markers of intTN916 played a key role in resistance to erythromycin in 100 ampicillin resistant S. flexneri. Three virulence genes spyA, sagA, and slo are common virulence genes of S. pyogenes. It is speculated that these three virulence genes are the causes of local inflammation and necrosis caused by S. pyogenes