背景:2016年12月在安达卢西亚引入了13价肺炎球菌结合疫苗(PCV13)通用疫苗接种计划。
方法:对肺炎球菌鼻咽定植的分子流行病学进行了横断面研究。在2018年1月4日至2020年2月28日和2021年1月11日至2022年2月28日(PCV13期)期间,总共从塞维利亚的初级保健中心招募了397名健康儿童。从2006年1月1日至2008年6月30日(PCV7期间)对健康和患病儿童进行的先前运输研究的数据,用于比较血清型/基因型分布和抗生素耐药率。
结果:总体而言,在PCV13期间,76名(19%)儿童定植了肺炎链球菌,并且在PCV7期间收集的154个分离株可获得信息。与历史对照相比,PCV13血清型的定植在PCV13期间显着下降(11%vs38%,p=0.0001),血清型19F(8%),3(1%)和6B(1%)是唯一的循环疫苗类型。血清型15B/C和11A是PCV13期间最常见的非PCV13血清型(14%和11%,分别);后者在不同时间段之间显著增加(p=0.04)。血清型11A在PCV13期仅与Spain9V-ST156克隆的氨苄青霉素抗性变体(ST6521和遗传相关的ST14698)相关,在前一期间未检测到。
结论:引入PCV13后,疫苗类型存在残留循环,除了血清型19F。由于氨苄青霉素抗性基因型ST6521的出现和克隆扩增,血清型11A在PCV13和PCV7期之间增加。
BACKGROUND: The 13-valent pneumococcal conjugate vaccine (PCV13) universal vaccination programme was introduced in December 2016 in Andalusia.
METHODS: A cross-sectional study was conducted on the molecular epidemiology of pneumococcal nasopharyngeal colonization. A total of 397 healthy children were recruited from primary healthcare centres in Seville for the periods 1/4/2018 to 28/2/2020 and 1/11/2021 to 28/2/2022 (PCV13 period). Data from a previous carriage study conducted among healthy and sick children from 1/01/2006 to 30/06/2008 (PCV7 period), were used for comparison of serotype/genotype distributions and antibiotic resistance rates.
RESULTS: Overall, 76 (19%) children were colonized with S. pneumoniae during the PCV13 period and there were information available from 154 isolates collected during the PCV7 period. Colonization with PCV13 serotypes declined significantly in the PCV13 period compared with historical controls (11% vs 38%, p = 0.0001), being serotypes 19F (8%), 3 (1%) and 6B (1%) the only circulating vaccine types. Serotypes 15B/C and 11A were the most frequently identified non-PCV13 serotypes during the PCV13 period (14% and 11%, respectively); the later one increased significantly between time periods (p = 0.04). Serotype 11A was exclusively associated in the PCV13 period with ampicillin-resistant variants of the Spain9V-ST156 clone (ST6521 and genetically related ST14698), not detected in the preceding period.
CONCLUSIONS: There was a residual circulation of vaccine types following PCV13 introduction, apart from serotype 19F. Serotype 11A increased between PCV13 and PCV7 periods due to emergence and clonal expansion of ampicillin-resistant genotype ST6521.