Background Streptococcus pyogenes-related skin infections are increasingly implicated in the development of rheumatic heart disease (RHD) in lower-resourced settings, where they are often associated with scabies. The true prevalence of S. pyogenes-related pyoderma may be underestimated by bacterial culture. Methods A multiplex qPCR for S. pyogenes, Staphylococcus aureus and Sarcoptes scabiei was applied to 250 pyoderma swabs from a cross-sectional study of children <5 years in The Gambia. Direct PCR-based emm-typing was used to supplement previous whole genome sequencing (WGS) of cultured isolates. Results Pyoderma lesions with S. pyogenes increased from 51% (127/250) using culture to 80% (199/250) with qPCR. Compared to qPCR, the sensitivity of culture was 95.4% for S. pyogenes (95% CI 77.2-99.9) in samples with S. pyogenes alone (22/250, 9%), but 59.9% (95% CI 52.3-67.2) for samples with S. aureus co-infection (177/250, 71%). Direct PCR-based emm-typing was successful in 50% (46/92) of cases, identifying 27 emm-types, including six not identified by WGS (total 52 emm-types). Conclusions Bacterial culture significantly underestimates the burden of S. pyogenes in pyoderma, particularly when co-infected with S. aureus. Molecular methods should be used to enhance the detection of S. pyogenes in surveillance studies and clinical trials of preventative measures in RHD-endemic settings.

中文翻译：

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分子方法增强了儿童脓皮病相关化脓性链球菌和 emm 型分布的检测


背景 化脓性链球菌相关的皮肤感染越来越多地与资源匮乏地区风湿性心脏病 (RHD) 的发生有关，通常与疥疮有关。细菌培养可能会低估与化脓性链球菌相关的脓皮病的真实患病率。方法 对来自冈比亚 <5 岁儿童横断面研究的 250 份脓皮病拭子应用针对化脓性链球菌、金黄色葡萄球菌和疥螨的多重 qPCR。基于直接 PCR 的 emm 分型用于补充之前培养分离株的全基因组测序 (WGS)。结果 化脓性链球菌引起的脓皮病病变从培养时的 51% (127/250) 增加到 qPCR 时的 80% (199/250)。与 qPCR 相比，在仅含有化脓性链球菌的样本中，培养物对化脓性链球菌的敏感性为 95.4% (95% CI 77.2-99.9) (22/250, 9%)，但为 59.9% (95% CI 52.3-67.2)对于金黄色葡萄球菌合并感染的样本（177/250，71%）。基于直接 PCR 的 emm 分型在 50% (46/92) 的病例中成功，识别出 27 种 emm 类型，其中包括 WGS 未识别的 6 种（总共 52 种 emm 类型）。结论 细菌培养显着低估了脓皮病中化脓性链球菌的负担，特别是与金黄色葡萄球菌合并感染时。在 RHD 流行环境中的预防措施的监测研究和临床试验中，应使用分子方法来加强化脓性链球菌的检测。