The Methodist Hospital Research Institute, Houston, Texas 77030, USA.
Emerg Infect Dis. 2011 Nov;17(11):2010-7. doi: 10.3201/eid1711.110159.
Group A Streptococcus (GAS) is a human-adapted pathogen that causes a variety of diseases, including pharyngitis and invasive infections. GAS strains are categorized by variation in the nucleotide sequence of the gene (emm) that encodes the M protein. To identify the emm types of GAS strains causing pharyngitis in Ontario, Canada, we sequenced the hypervariable region of the emm gene in 4,635 pharyngeal GAS isolates collected during 2002-2010. The most prevalent emm types varied little from year to year. In contrast, fine-scale geographic analysis identified inter-site variability in the most common emm types. Additionally, we observed fluctuations in yearly frequency of emm3 strains from pharyngitis patients that coincided with peaks of emm3 invasive infections. We also discovered a striking increase in frequency of emm89 strains among isolates from patients with pharyngitis and invasive disease. These findings about the epidemiology of GAS are potentially useful for vaccine research.
A 组链球菌（GAS）是一种适应人类的病原体，可引起多种疾病，包括咽炎和侵袭性感染。GAS 菌株根据编码 M 蛋白的基因（emm）核苷酸序列的变异进行分类。为了确定在加拿大安大略省引起咽炎的 GAS 菌株的 emm 型，我们对 2002-2010 年间采集的 4635 株咽峡部 GAS 分离株的 emm 基因的高变区进行了测序。最常见的 emm 型的流行程度每年变化不大。相比之下，精细的地理分析确定了最常见的 emm 型在不同地点之间的变异性。此外，我们还观察到来自咽炎患者的 emm3 菌株的年度频率波动与 emm3 侵袭性感染的高峰相吻合。我们还发现，来自咽炎和侵袭性疾病患者的分离株中 emm89 菌株的频率显著增加。这些关于 GAS 流行病学的发现对于疫苗研究可能是有用的。
