Bessen D E, Carapetis J R, Beall B, Katz R, Hibble M, Currie B J, Collingridge T, Izzo M W, Scaramuzzino D A, Sriprakash K S
Yale University School of Medicine, Dept. of Epidemiology and Public Health, New Haven, CT 06520.
J Infect Dis. 2000 Oct;182(4):1109-16. doi: 10.1086/315842. Epub 2000 Sep 8.
Disease caused by group A streptococci (GAS) in tropical regions often takes the form of impetigo, whereas pharyngitis tends to predominate in temperate zones. GAS derived from asymptomatic throat infections and pyoderma lesions of rural Aboriginal Australians were evaluated for phylogenetic distant emm genes, which represent ecological markers for tissue site preference. On the basis of the percentage of total isolates from a given tissue, emm pattern A-C organisms exhibited a stronger predilection for the throat, whereas pattern D organisms preferred the skin. Only 16% of isolates collected by active surveillance displayed pattern A-C, which reflects the low incidence of oropharyngeal infection. Importantly, most (70%) pattern A-C organisms were isolated from skin sores, despite their innate tendency to infect the throat. Combined with findings from nontropical populations, analysis of the data supports the hypothesis that GAS tissue preferences are genetically predetermined and that host risk factors for infection strongly influence the differential reproduction of individual clones.
在热带地区，A 组链球菌（GAS）引起的疾病通常表现为脓疱病，而在温带地区咽炎往往更为常见。对来自澳大利亚农村原住民无症状咽喉感染和脓皮病病变的 GAS 进行了评估，以检测其亲缘关系较远的 emm 基因，这些基因代表了组织部位偏好的生态标记。根据来自特定组织的分离株总数百分比，emm 模式 A - C 的菌株对咽喉表现出更强的偏好，而模式 D 的菌株则更倾向于皮肤。通过主动监测收集的分离株中只有 16%表现出模式 A - C，这反映了口咽感染的低发病率。重要的是，尽管大多数（70%）模式 A - C 的菌株天生倾向于感染咽喉，但它们却是从皮肤溃疡中分离出来的。结合非热带人群的研究结果，对这些数据的分析支持了以下假设：GAS 对组织的偏好是由基因预先决定的，并且宿主感染风险因素强烈影响个体克隆的差异繁殖。
