Laboratorio de Microbiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
Epidemiol Infect. 2012 Jul;140(7):1286-95. doi: 10.1017/S0950268811001889. Epub 2011 Sep 12.
Streptococcus pyogenes causes a variety of infections because of virulence factors such as capsular hyaluronic acid and M protein. The aim of this study was to determine emm types and capsule phenotype in 110 isolates of S. pyogenes from patients with invasive (sterile sites) and non-invasive (mainly pharyngitis) infections in Chile, and the relationship between both virulence factors. The most abundant types found were emm12, emm1, emm4 and emm28 and their distribution was similar to that seen in Latin America and developed countries, but very different from that in Asia and Pacific Island countries. Ten of 16 emm types identified in pharyngeal isolates were found in sterile-site isolates, and three of nine emm types of sterile-site isolates occurred in pharyngeal isolates; three emm subtypes were novel. The amount of hyaluronic acid was significantly higher in sterile-site isolates but did not differ substantially among emm types. Only three isolates were markedly capsulate and two of them had mutations in the csrR gene that codes for a repressor of capsule synthesis genes. We found a non-random association between emm types and csrR gene alleles suggesting that horizontal gene transfer is not freely occurring in the population.
化脓链球菌由于荚膜透明质酸和 M 蛋白等毒力因子可引起多种感染。本研究旨在确定来自智利侵袭性（无菌部位）和非侵袭性（主要为咽炎）感染患者的 110 株化脓链球菌分离株的emm 型和荚膜表型，以及这两种毒力因子之间的关系。发现最丰富的类型是 emm12、emm1、emm4 和 emm28，其分布与拉丁美洲和发达国家相似，但与亚洲和太平洋岛国非常不同。16 种咽部分离株鉴定的 emm 型中有 10 种存在于无菌部位分离株中，9 种无菌部位分离株的 emm 型中有 3 种存在于咽部分离株中；有 3 种 emm 亚型是新发现的。无菌部位分离株的透明质酸含量明显较高，但在 emm 型之间没有显著差异。只有 3 株明显有荚膜，其中 2 株在编码荚膜合成基因的 csrR 基因中有突变。我们发现 emm 型和 csrR 基因等位基因之间存在非随机关联，这表明水平基因转移在人群中并非自由发生。
