Department of Dermatology, Peking University People's Hospital, Beijing, China.
Clin Microbiol Infect. 2011 Aug;17(8):1246-53. doi: 10.1111/j.1469-0691.2010.03404.x. Epub 2010 Dec 3.
The prevalence of the newly discovered pneumococcal serotype 6C has increased in some countries since the introduction of seven-valent conjugate pneumococcal vaccine (PCV7). The distribution of invasive serogroup 6 serotypes, in Australia, including 6C and 6D, has not been reported previously. During the period 1999 to 2008, 6097 isolates were referred to the New South Wales Pneumococcal Reference Laboratory for serotyping. Of these, 847 were identified by Quellung reaction as belonging to serogroup 6 and 702 were available for further study. Serotypes were determined by serotype-specific PCR as follows: 6A, 197 (28.1%); 6B, 452 (64.4%); 6C, 52 (7.4%) and one 6D. The average numbers of invasive serogroup 6 isolates, per annum, fell from 62.2 before (2000-2005) to 49.7 after (2006-2008) the introduction of PCV7. The proportions of invasive 6B fell (from 72.4% to 47.3%, p 0.03), those of 6C rose (from 3.3% to 17%, p 0.02) significantly and those of 6A remained fairly constant (24.3% vs 27%, p 0.69) between the two periods. All 6C and 6D and selected 6A and 6B isolates were further characterized by multilocus sequence typing and sequence analysis of cps genes cpsA-cpsB (wzg-wzh) and wchA-wciN(beta) -wciO, wciP. Results showed considerable diversity within serotype 6C, apparently as a result of both mutation and recombination. Sequence typing indicates that, in Australia, 6C has been largely derived from 6A. The genetic diversity and rapid increase in incidence of serotype 6C causing invasive pneumococcal disease has potential implications for vaccine efficacy.
自 7 价结合型肺炎球菌疫苗（PCV7）问世以来，某些国家新发现的肺炎球菌 6C 血清型的流行率有所增加。澳大利亚侵袭性血清群 6 血清型（包括 6C 和 6D）的分布情况此前尚未报道。1999 年至 2008 年期间，新南威尔士肺炎球菌参考实验室对 6097 株分离株进行了血清分型。其中，847 株经胶乳反应确认为血清群 6，702 株可供进一步研究。通过血清型特异性 PCR 确定血清型如下：6A，197（28.1%）；6B，452（64.4%）；6C，52（7.4%）和 1 株 6D。每年侵袭性血清群 6 分离株的平均数量从 PCV7 引入前（2000-2005 年）的 62.2 株降至引入后（2006-2008 年）的 49.7 株。侵袭性 6B 的比例下降（从 72.4%降至 47.3%，p 0.03），6C 的比例上升（从 3.3%升至 17%，p 0.02），而 6A 的比例在两个时期之间基本保持不变（24.3%比 27%，p 0.69）。所有 6C 和 6D 以及选定的 6A 和 6B 分离株均通过多位点序列分型和 cps 基因 cpsA-cpsB（wzg-wzh）和 wchA-wciN(beta) -wciO、wciP 的序列分析进行了进一步表征。结果表明，6C 内存在明显的多样性，显然是由于突变和重组所致。序列分型表明，在澳大利亚，6C 主要源自 6A。6C 引起侵袭性肺炎球菌病的发生率增加和遗传多样性具有疫苗效力的潜在影响。
