Demczuk Walter H B, Martin Irene, Hoang Linda, Van Caeseele Paul, Lefebvre Brigitte, Horsman Greg, Haldane David, Gubbay Jonathan, Ratnam Sam, German Gregory, Daley Bernier Jennifer, Strudwick Lori, McGeer Allison, Zhanel George G, Van Domselaar Gary, Graham Morag, Mulvey Michael R
National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
British Columbia Centre for Disease Control, Vancouver, British, Canada.
PLoS One. 2017 May 22;12(5):e0178040. doi: 10.1371/journal.pone.0178040. eCollection 2017.
Since implementation of the 13-valent polyvalent conjugate vaccine (PCV13) in Canada during 2010, the proportion of PCV13 serotypes causing invasive pneumococcal disease (IPD) has declined from 55% (n = 1492) in 2010 to 31% (n = 764) in 2014. A concurrent increase of non-PCV13 serotypes has occurred and 22F has become the most prevalent serotype in Canada increasing from 7% (n = 183) to 11% (n = 283). Core single nucleotide variant phylogenetic analysis was performed on 137 Streptococcus pneumoniae serotype 22F isolates collected across Canada from 2005-2015. Six phylogenetic lineages (n = 117) were identified among a serotype 22F/ST433 clonal complex (CC), including a recently expanding erythromycin-resistant clone. Erythromycin-resistance was observed in 25 isolates possessing ermB, mef or a 23S rRNA A2061G point mutation; 2 penicillin-resistant isolates had recombinant pbp1a, pbp2a and/or pbp2x; 3 tetracycline-resistant isolates contained tetM; and 1 isolate was multidrug-resistant. Virulence factor analysis indicated a high level of homogeneity among the 22F/ST433 clonal complex strains. A group of 6 phylogenetic outlier strains had differing MLST, antimicrobial resistance and molecular profiles suggestive of capsule switching events. While capsule switch events among S. pneumoniae serotype 22F has been observed, increasing prevalence of S. pneumoniae serotype 22F can be attributed to an evolving homogenous clone expanding nationally through local transmission events.
自2010年加拿大实施13价多价结合疫苗（PCV13）以来，引起侵袭性肺炎球菌疾病（IPD）的PCV13血清型比例已从2010年的55%（n = 1492）降至2014年的31%（n = 764）。同时，非PCV13血清型有所增加，22F已成为加拿大最常见的血清型，从7%（n = 183）增至11%（n = 283）。对2005年至2015年在加拿大各地收集的137株肺炎链球菌22F血清型分离株进行了核心单核苷酸变异系统发育分析。在22F/ST433克隆复合体（CC）中鉴定出6个系统发育谱系（n = 117），包括一个最近正在扩张的耐红霉素克隆。在25株携带ermB、mef或23S rRNA A2061G点突变的分离株中观察到耐红霉素现象；2株耐青霉素分离株具有重组pbp1a、pbp2a和/或pbp2x；3株耐四环素分离株含有tetM；1株分离株为多重耐药。毒力因子分析表明22F/ST433克隆复合体菌株之间具有高度同质性。一组6株系统发育异常菌株具有不同的多位点序列分型、抗菌药物耐药性和分子特征，提示发生了荚膜转换事件。虽然已观察到肺炎链球菌22F血清型之间的荚膜转换事件，但肺炎链球菌22F血清型患病率的增加可归因于一个不断演变的同质克隆通过局部传播事件在全国范围内扩张。
