Manning Shannon D, Lewis Maggi A, Springman A Cody, Lehotzky Erica, Whittam Thomas S, Davies H Dele
Microbial Evolution Laboratory, National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan, USA.
Clin Infect Dis. 2008 Jun 15;46(12):1829-37. doi: 10.1086/588296.
Most studies of the dynamics of maternal group B Streptococcus (GBS) colonization have relied on capsular serotyping to define GBS acquisition or loss. Newer molecular methods that distinguish GBS clones may expand our knowledge and influence vaccination strategies. We used multilocus sequence typing (MLST) and GBS capsular gene cluster (cps) genotyping to investigate the dynamics of perinatal GBS colonization.
A total of 338 GBS isolates obtained from 212 colonized women who were enrolled in a prior prospective cohort study were serotyped and genotyped by MLST and cps typing before (visit 1) and 6 weeks after (visit 2) delivery.
Of the 212 women, 126 were colonized at both visits, whereas 66 lost and 20 acquired GBS by visit 2. MLST of the 338 strains identified 29 sequence types marking distinct bacterial clones. A change in sequence type or cps and serotype occurred in 23 (18.3%) of the 126 women who were colonized at both visits. Specific sequence types were associated with GBS loss and persistence. Older maternal age and exclusive intrapartum antibiotic use were associated with persistent colonization.
Although most GBS-positive pregnant women were stably colonized during the peripartum period, we detected changes in capsule expression and recolonization with antigenically distinct GBS clones over time by applying MLST. Combining the epidemiologic and molecular typing data revealed host factors and clones associated with persistent colonization, as well as a clone that was more readily lost. This knowledge is useful for the development of prevention and intervention strategies to reduce the likelihood of maternal GBS colonization.
大多数关于孕产妇B族链球菌（GBS）定植动态的研究都依赖于荚膜血清分型来定义GBS的获得或丢失。区分GBS克隆的更新分子方法可能会扩展我们的知识并影响疫苗接种策略。我们使用多位点序列分型（MLST）和GBS荚膜基因簇（cps）基因分型来研究围产期GBS定植的动态变化。
从之前一项前瞻性队列研究中纳入的212名定植GBS的女性中获得的338株GBS分离株，在分娩前（第1次访视）和分娩后6周（第2次访视）通过MLST和cps分型进行血清分型和基因分型。
在212名女性中，126名在两次访视时均定植GBS，而到第2次访视时，66名失去了GBS定植，20名获得了GBS定植。对338株菌株进行MLST鉴定出29种序列类型，标记了不同的细菌克隆。在两次访视时均定植GBS的126名女性中，有23名（18.3%）发生了序列类型、cps和血清型的变化。特定的序列类型与GBS的丢失和持续存在有关。产妇年龄较大和仅在产时使用抗生素与持续定植有关。
尽管大多数GBS阳性孕妇在围产期稳定定植GBS，但通过应用MLST，我们检测到随着时间推移，荚膜表达发生变化，并且出现了抗原性不同的GBS克隆重新定植的情况。结合流行病学和分子分型数据揭示了与持续定植相关的宿主因素和克隆，以及更容易丢失的克隆。这些知识有助于制定预防和干预策略，以降低孕产妇GBS定植的可能性。
