疫苗引入前苏州地区儿童肺炎链球菌的分子流行病学特征研究

Molecular characterization of Streptococcus pneumoniae isolated from children in Suzhou before the introduction of pneumococcal vaccine

目的了解苏州地区在7价肺炎链球菌结合疫苗（7 heptavalent pneumococcal conjugate vaccine，PCV7）引入前，不同临床治疗压力下肺炎链球菌分离株的耐药特征、血清分型及国际流行耐药克隆株（pneumococ-cal molecular epidemiology network，PMEN）的流行情况。方法收集2006年3月-2007年3月期间苏州大学附属儿童医院住院治疗的呼吸道感染儿童（病例组）和非呼吸道感染儿童（对照组）中分离的肺炎链球菌134株，进行抗生素敏感性分析和血清型分型，并对其中86株大环内酯类药物菌株进行基因分型。结果病例组抗生素的使用率高于对照组（x2=111．19，P〈0．001）。病例组分离的菌株血清型以19F、19A和14为主，对照组菌株常见的血清型为6B、19F和23F，两组PCV7血清型覆盖率分别为58．3％和68．1％。对照组菌株对常用抗生素的敏感性均高于病例组（均有P〈0．05）。菌株基因分型共检测出10种PMEN克隆株，最常见的为Taiwan19F-14克隆株。PMEN克隆株对常用抗菌药物的不敏感率高于非PMEN克隆株。结论在我国引入PCV7前，在抗生素等治疗压力下，苏州地区肺炎链球菌的耐药情况严重，以Taiwan19F-14克隆株流行为主，多种PMEN克隆株并存。

Objective To explore the serotype distribution, antibiotics sensitivity and molecular characteristics of pneumococci before the introduction of PCV7 in Suzhou. Methods A case-control study was conducted in Soochow Uni- versity Affiliated Children＇ s Hospital from March 2006 to March 2007. 134 S. pneumoniae strains were isolated from naso- pharyngeal swabs or aspirates among the children in this study. Antibiotics sensitivity and serotyping were tested in all strains. Sequence types were tested in 86 macrolide-resistant strains. Results The utilization rate of antibiotics in cases was significantly higher than that in controls. The most common serotypes of pneumococci were 19F, 19A and 14 among ca- ses, and 6B, 19F, 23F among controls. The coverage rate of PCV7 among cases and controls were 58.3% and 68. 1%, respectively. The sensitivity rates of the isolates to common antibiotics were higher in control isolates than that in cases iso- lates. In total, 10 PMEN clones were identified, and Taiwan19F-14 clones were the dominated clones. Compared to non- PMEN clones, PMEN clones presented a higher antibiotic resistantce. Conclusions Under the selective pressure of anti- biotics, S. pneumoniae strains showed a high rate of drug resistance in the pre-PCV7 era. PMEN14 clones were the pre- dominate clones and mainly responsible for the antibiotic resistance in this area.