摘要
目的 研究上海3所医院临床分离肺炎链球菌对大环内酯类抗生素的耐药机制及传播方式。方法收集上海市3所医院临床分离的红霉素耐药肺炎链球菌共118株，用E试验和K-B纸片扩散法检测对12种抗菌药的敏感度；用双纸片法（D试验）确定大环内酯类耐药表型；用PCR扩增检测耐药基因ermB、mefA、mefE、msrD及Tn1545-Tn916家族转座子整合酶基因intTn；用转化试验证实耐药传播方式。结果①118株肺炎链球菌对红霉素的MIC范围为4-256mg／L，其中5．9％对克林霉素敏感，对青霉素不敏感率达72．7％。左氧氟沙星、阿莫西林-克拉维酸对红霉素耐药的肺炎链球菌仍有较好的体外活性；②该组细菌耐药基因ermB检出率为88．1％，mefE、msrD检出率各为50％，未检出，mefA基因，转座子整合酶基因intTn检出率达97．5％。耐药基因组合模式以ermB（＋）reefE（＋）msrD（＋）intTn（＋）和ermB（＋）mefE（-）msrD（-）intTn（＋）为主，两者均为cMLSB型耐药。ermB（-）mefE（＋）msrD（＋）intTn（＋）模式占5．9％，耐药表型为M型。③cMLSB型耐药代表菌株ET37和M型耐药代表菌株RJ324基因组DNA均成功转化敏感株，使之表现红霉素耐药性并可传代。结论上海地区肺炎链球菌对大环内酯抗生素耐药以ermB介导的cMLSB耐药表型为主；大环内酯外排基因有流行趋势，但仅限于起源于肺炎链球菌的，mefE。耐药基因可以转化方式进行传播，转座子可能在本地区肺炎链球菌耐药基因的传播中起重要作用。
Objective To analyze the mechanism of macrolide resistance and characterize the dissemination of resistance gene in Streptococcus pneurnoniae isolates from Shanghai. Methods Antibiotic susceptibility was determined by E test method or KirbyBauer disk diffusion test according to National Committee for Clinical Laboratory Standards. Macrolide-resistant phenotypes were classified using a double disc test with erythromycin and clindamycin. The ermB, mefA, mefE, rnsrD and intTn genes were amplified by PCR. The dissemination of resistant gene was characterized by transformation. Results Of the 118 erythromycin-resistant isolates, only 5.9% were susceptible to clindamycin, 72.7% were non-susceptible to penicillin. Amoxicillinclavulanate and levofloxacin showed good activity against most of the erythromycin-resistant isolates. The prevalence of resistant genes was identified as follows： errnB, 88. 1%; mefE, 50%; msrD 50%; rnefA 0%; and transposon integrase gene （intTn） 97.5%. The most common macrolide resistance phenotype was cMLSB phenotype （94. 1 %）, which had ermB（＋） rnefE（ ＋ ） rnsrD（ ＋ ） int Tn （ ＋ ） and ermB （ ＋ ） rnefE（ - ） rnsrD （ -- ） int Tn （ ＋ ） genotype patterns. About 5.9 % of the isolates showed M phenotype, which had errnB（-）mefE（＋）rnsrD（＋）intTn（＋） pattern. The resistant gene can be disseminated by transformation. Conclusions In Shanghai,ermB-mediated cMLSB is the most prevalent phenotype among erythromycin-resistant S. pneumoniae isolates. There is a tendency that the mefE gene derived from S. pneumoniae can spread rapidly. Transposonmay play an important role in the dissemination of resistance genes in S. pneumoniae.
出处
《中国感染与化疗杂志》
CAS
2006年第2期85-88,共4页
Chinese Journal of Infection and Chemotherapy
基金
上海交通大学医学院博士点基金资助
关键词
肺炎链球菌
大环内酯
耐药机制
Streptococcus pneumoniae
Macrolides
Resistance mechanism
