Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
Pediatr Infect Dis J. 2011 Apr;30(4):302-8. doi: 10.1097/INF.0b013e318201a154.
Vaccination against 7 serotypes of Streptococcus pneumoniae has led to the near extinction of vaccine serotypes in both disease and asymptomatic carriage. In carriage, vaccine serotypes have been replaced by nonvaccine serotypes.
We used multilocus sequence typing to analyze a sample of 294 isolates of S. pneumoniae carried by Massachusetts children (aged, 3 months-7 years) and examine the results for serotype switching and association with antimicrobial resistance.
Eighty-six distinct sequence types (STs) were found, 10 of which exhibited a serotype other than that which would be expected from previous carriage samples. We interpret this as evidence of past or recent serotype switching. Switched variants include ST 320, which is a common and increasing source of multidrug resistance in this community. Switching events within serogroups were more common than expected by chance (P = 0.043 by a Monte Carlo approach). Using multilocus sequence typing data and eBURST analysis, we also describe clonal dynamics within the important replacement serotypes 19A, 15B/C, 35B, and the recently described 6C.
Some strains generated by serotype switching are increasingly important parts of the carriage population. In the case of 19A, it appears that the majority of increase is due to ST 320, a recently reported switched variant. This may have consequences for the STs causing invasive pneumococcal disease.
对 7 种血清型肺炎链球菌的疫苗接种导致了疾病和无症状携带中疫苗血清型的近乎灭绝。在携带中，疫苗血清型已被非疫苗血清型取代。
我们使用多位点序列分型分析了马萨诸塞州儿童（3 个月至 7 岁）携带的 294 株肺炎链球菌样本，并对血清型转换和与抗菌药物耐药性的关系进行了研究。
发现了 86 个不同的序列型（ST），其中 10 个表现出与之前携带样本不同的血清型，我们将其解释为过去或近期血清型转换的证据。转换的变体包括 ST320，这是该社区中常见且不断增加的多药耐药来源。血清组内的转换事件比预期的更常见（通过蒙特卡罗方法，P=0.043）。我们还使用多位点序列分型数据和 eBURST 分析描述了重要替代血清型 19A、15B/C、35B 和最近描述的 6C 中的克隆动态。
一些由血清型转换产生的菌株是携带人群中越来越重要的部分。对于 19A 而言，其增加的大部分似乎归因于 ST320，这是一种最近报道的转换变体。这可能对引起侵袭性肺炎球菌病的 ST 产生影响。
