新生儿B组链球菌感染传播途径的研究

The different transmission of group B streptococcus infections in neonates

目的 确定新生儿B组链球菌 (GBS)感染的传播途径和随机引物扩增多态性 (RAPD)分型方法的应用价值。方法 采用血清学、核酸杂交和PARD方法对从 2例诊断为早发型GBS肺炎和晚发型GBS脑膜炎患儿体内分离的 5株GBS和其母阴道分离的 2株GBS菌株作母婴配对分析 ,对 88株孕妇生殖道携带GBS进行RAPD分型研究。结果 1例早发型GBS肺炎母婴配对GBS血清型均为III/R型致病 ,毒力因子基因片段大小 [α和β基因均为阴性 ,凝聚因子基因 (ScaA) 2kb ,谷氨酰胺基因(glnA) 6 .5kb ,ScpB 2 .6kb]和DNA指纹图完全一致 ;1例晚发型GBS脑膜炎母婴配对GBS菌血清型均为III/R型致病、毒力因子基因片段大小 (α和 β基因均为阴性 ,ScaA 2kb ,glnA 6 .5kb ,ScpB 2 .6kb)均相同 ,而RAPD的DNA指纹图不同 ,孕妇携带GBS菌株为RAPD2 7型 ,而患儿血和脑脊液分离的GBS菌株均为RAPD1型。RAPD分型方法的分型率分辨力高、稳定性强。结论 1例早发型GBS感染为母婴垂直传播 ,1例晚发型GBS感染可能与生后水平传播有关 ;RAPD分型方法在GBS感染流行病学研究中具有潜在使用价值。

Objective To study the transmission of group B Streptococcus (GBS) in the neonatal infections and the value of randomly amplified polymorphic DNA(RAPD) analysis in the GBS epidemiology. Methods The serotyping, hybridization and RAPD typing methods were used. Seven strains of GBS were detected in 2 pairs of mother-baby, which included 2 strains from the 2 mothers and 5 strains from their babies with early and late-onset infections. Eighty-eight strains of GBS were detected in vaginas of pregnant womens. Results In the two cases, the strains from the paired mother and baby showed the identical serotype (III/R) and restriction fragment length of virulent factor genes that is , alpha and beta genes negative, ScaA 2kb, glnA 6.5kb and ScpB 2.6kb. In the case with early-onset infection, the strains from the paired mother and baby were revealed with the identical RAPD pattern ( RAPD1). In the case with late-onset infection, the strains from the paired mother and baby were revealed with different RAPD patterns, GBS strain isolated from mother was RAPD27, GBS strains from blood and CSF of the baby were RAPD1. Conclusion There may be a vertical transmission between mother and baby in early-onset of GBS infection and cross transmission in late-onset. RAPD analysis provides a valuable molecular tool for studying GBS epidemiology.