Background

S. pneumoniae carriage by children is a major source of pneumococcal transmission, and the initial step prior to infection. Pilus type 1, reported in ~30% of pneumococcal strains in the pre-vaccine era, contributes to pneumococcal colonization and virulence. In this study, we report the impact of the pneumococcal conjugate vaccine (PCV), PCV7/PCV13 sequential implementation on serotype distribution, and on the prevalence of piliated strains among carried pneumococci during the pre- and post-vaccine eras.

Methods

During 2002-2016, 12 repeated cross-sectional surveillances of nasopharyngeal S. pneumoniae carriage were conducted among 8,473 children <5.5 years old visiting primary care physicians in Central Israel. Seven biannual surveillances in the pre-PCV period, 2 surveillances after PCV7 was licensed but before implementation in the National Immunization Plan, and 3 additional surveillances in the post-PCV period. S. pneumoniae serotype distribution and prevalence of piliated strains were assessed.

Results

Carriage of S. pneumoniae was relatively stable (45.4%). The prevalence of serotypes included in PCV13 was 65.7%, in the pre-vaccine period and the pilus was present in 26.4% of isolates. The distribution of serotypes and the pilus prevalence in the pre-PCV period was relatively stable except for a decrease in prevalence of piliated 19F, observed following the first study year. Following PCV7/PCV13 implementation, vaccine type 13 (VT13) strains were nearly eliminated to 3.3% by 2016. Piliated strains, which were primarily of VT13 serotypes, initially followed a similar trend and were nearly eliminated by 2014 (1.7%). Yet, two years later, pilus prevalence re-emerged among non-VT strains to 12.8% of all pneumococci.

Conclusions

Following PCV implementation, a dramatic and rapid decrease in VT strains prevalence was observed with a concomitant increase in non-VT strains. Piliated strains were nearly eliminated, yet re-emerged 7 years following PCV7/PCV13 implementation in various non-VT strains. This suggests that the pilus confers an advantage in colonization.

中文翻译：

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PCV7 / 13对携带的肺炎球菌血清型分布和菌毛患病率的影响；14年反复断面监视

背景

儿童携带的肺炎链球菌是肺炎球菌传播的主要来源，也是感染前的第一步。在疫苗接种前的大约30％的肺炎球菌菌株中报告了1型毛发，这有助于肺炎球菌的定殖和致病性。在这项研究中，我们报告了肺炎球菌结合疫苗（PCV），PCV7 / PCV13顺序实施对血清型分布的影响，以及在疫苗接种前和疫苗接种后时代携带的肺炎球菌中被感染菌株的流行。

方法

在2002年至2016年期间，在以色列中部的8,473名5.5岁以下的儿童中，对12名反复感染鼻咽链球菌的儿童进行了12次重复监测。在PCV之前的时期进行七次半年度监视，在获得PCV7许可后但在《国家免疫计划》实施之前进行两次监视，在PCV之后的时期进行三次附加监视。评估了肺炎链球菌血清型分布和纤毛菌株的患病率。

结果

肺炎链球菌的运输相对稳定（45.4％）。在疫苗接种前期，PCV13中血清型的流行率为65.7％，菌毛中有26.4％的分离株存在。在第一个研究年后观察到，PCV前期的血清型分布和菌毛患病率相对稳定，但毛状19F的患病率有所降低。在实施PCV7 / PCV13之后，到2016年，13型疫苗（VT13）株几乎被淘汰，降至3.3％。主要是VT13血清型的菌丝状菌株最初也遵循类似的趋势，到2014年几乎被淘汰（1.7％）。然而，两年后，非VT菌株中的菌毛流行再次出现，占所有肺炎球菌的12.8％。

结论

实施PCV后，观察到VT菌株的流行率急剧下降，而非VT菌株随之增加。丝状菌株几乎被消除，但在各种非VT菌株中实施PCV7 / PCV13后7年又重新出现。这表明菌毛赋予了定植优势。