北京地区青霉素不敏感肺炎链球菌分子流行病学的初步探讨

目的了解北京地区儿童中青霉素不敏感肺炎链球菌（PNSP）的流行状况,阐明其分子流行病学特征。方法以2000-2002年于0～5岁上呼吸道感染儿童鼻咽部分离的63株PNSP冻存标本为研究对象,进行耐药模式分析,以聚合酶链反应（PCR）扩增青霉素结合蛋白（PBP）基因pbpla、pbp2b和pbp2x,分析其限制性片段长度多态性（RFLP）,并进行细菌染色体RFLP脉冲场凝胶电泳（PFGE）比较。结果63株PNSP有61株（96．8％）为多重耐药菌株。pbpla、pbp2b和pbp2x分别有8、9和18种基因型,三者组合的谱型共有30种。63株PNSP的PFGE型共分为35个,其中,9种PFGE型包括菌株≥2株,这9种型共包含37株,占59％,均为多重耐药菌株。与亚洲流行菌株比较,我们发现2株PFGE型可能相关的PNSP分别与亚洲流行菌株越南-19群、新加坡-19群、中国台湾-19群和韩国-19群谱型完全相同。结论北京地区儿童中PNSP的多重耐药状况严峻,克隆传播是PNSP流行的重要因素;已存在与亚洲流行菌株相同的克隆,值得关注。

Molecular epidemiology of penicillin-nonsusceptible Streptococcus pneumoniae in Beijing, China, 2000-2002

OBJECTIVE: To investigate the molecular epidemiology of the penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) in Beijing, China. METHODS: The resistant profile of 63 PNSP strains isolated from children with upper respiratory infection in the outpatient department from 2000 to 2002 was analyzed. The isolates were compared by detecting restriction fragment length polymorphism (RFLP) of the penicillin-binding protein (PBP) genes pbp1a, pbp2b and pbp2x and by applying chromosomal macrorestriction patterns detected by pulsed-field gel electrophoresis (PFGE). RESULTS: Sixty-one (96.8%) out of the 63 PNSP strains were multidrug-resistant Streptococcus pneumoniae (Sp). Overall, 16 resistance profiles were found, 14 of which were multidrug resistant profiles. Seven (33.3%), 6 (24.0%) and 8 (47.1%) strains resistant to one of cephalosporins were respectively isolated in 2000, 2001 and 2002, indicating an increasing trend but without any statistical significance (chi(2) = 2.42, P > 0.05). The RFLP results showed 8, 9 and 18 genotypes of pbp1a, pbp2b and pbp2x, respectively. A total of 30 patterns were found according to the three pbps types. And clearly, the most common 5 patterns had main resistant profiles. In the mean time, 35 different PFGE types were elucidated and the 9 PFGE types, with each consisting of more than 2 strains, covered 59% (37/63) of all isolates. One of the 9 PFGE type included 2 strains, both possibly related to each other, but one of them was detected to be the same PFGE pattern with clones prevalent in Asia, Vietnam-19 serogroup, Singapore-19 serogroup, Taiwan-19 serogroup, and the other was the same as that in Korea-19 serogroup. CONCLUSION: Multidrug resistance is very common among PNSP isolates in Beijing. The spread of a few multidrug resistant clones is an important factor for the prevalence of PNSP. It deserves the concern that the resistant clones spread in Asia have been found in Beijing.