Department of Medical Microbiology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 727 McDermot Avenue, Winnipeg, Manitoba R3E 3P5, Canada.
Clinical Microbiology - Health Sciences Centre, Diagnostic Services Manitoba, MS673-820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9, Canada.
J Antimicrob Chemother. 2018 Jul 1;73(suppl_7):vii20-vii31. doi: 10.1093/jac/dky157.
This study characterized the 11 most predominant serotypes of invasive Streptococcus pneumoniae infections collected by the annual SAVE study in Canada, between 2011 and 2015.
A subset of the 11 most predominant serotypes (7F, 19A, 22F, 3, 12F, 11A, 9N, 8, 33F, 15A and 6C) collected by the SAVE study was analysed using PFGE and MLST, as well as PCR to identify pilus-encoding genes. WGS analyses were performed on a subset of the above isolates plus a random selection of background strains.
Of the predominant serotypes analysed, 7F, 33F and 19A were obtained more commonly from children <6 years of age, whereas 15A, 6C, 22F and 11A were more common in adults >65 years of age. Pneumococcal pilus PI-1 was identified in antimicrobial-susceptible serotype 15A (61/212) and <10% of 6C isolates (16/188). PI-2 was found in serotype 7F (683/701) and two-thirds of 11A isolates (162/241). Only serotype 19A-ST320 possessed both pili. Molecular and phylogenetic analyses identified serotypes 19A, 15A, 6C, 9N and 33F as highly diverse, whereas 7F, 22F and 11A demonstrated clonality. Antimicrobial resistance determinants were common within diverse serotypes, and usually similar within a clonal complex.
Despite successful use of conjugate vaccines, S. pneumoniae remains a highly diverse organism in Canada. Several predominant serotypes, both antimicrobial susceptible and MDR, have demonstrated rapid clonal expansion or an increase in diversity. As S. pneumoniae continues to evolve in Canada, WGS will be a necessary component in the ongoing surveillance of antimicrobial-resistant and expanding clones.
本研究对 2011 年至 2015 年期间加拿大年度 SAVE 研究中收集的侵袭性肺炎链球菌感染的 11 种最主要血清型进行了特征描述。
使用 PFGE 和 MLST 以及 PCR 对 SAVE 研究中收集的 11 种最主要血清型（7F、19A、22F、3、12F、11A、9N、8、33F、15A 和 6C）的一个亚组进行分析，以鉴定菌毛编码基因。对上述分离株的一个亚组以及随机选择的背景菌株进行 WGS 分析。
在所分析的主要血清型中，7F、33F 和 19A 更常见于<6 岁的儿童，而 15A、6C、22F 和 11A 则更常见于>65 岁的成年人。在抗菌药物敏感的血清型 15A（61/212）中发现了肺炎球菌菌毛 PI-1，在<10%的 6C 分离株（16/188）中发现了 PI-2。PI-2 存在于血清型 7F（683/701）和三分之二的 11A 分离株（162/241）中。只有血清型 19A-ST320 同时具有这两种菌毛。分子和系统发育分析表明，血清型 19A、15A、6C、9N 和 33F 高度多样化，而 7F、22F 和 11A 则表现出克隆性。在不同血清型中，抗菌药物耐药决定因素很常见，并且在一个克隆复合体中通常相似。
尽管使用了结合疫苗，但肺炎链球菌在加拿大仍然是一种高度多样化的病原体。一些主要的血清型，包括对抗菌药物敏感和多药耐药的血清型，已经表现出快速的克隆扩张或多样性增加。随着肺炎链球菌在加拿大的不断进化，WGS 将成为持续监测抗菌药物耐药和不断扩大的克隆的必要组成部分。
