Plainvert Céline, Dinis Márcia, Ravins Miriam, Hanski Emanuel, Touak Gérald, Dmytruk Nicolas, Fouet Agnès, Poyart Claire
Assistance Publique Hôpitaux de Paris, Service de Bactériologie, Centre National de Référence des Streptocoques, Groupe Hospitalier Paris Centre Cochin-Hôtel Dieu-Broca, Paris, France INSERM, U1016, Institut Cochin, Paris, France CNRS (UMR 8104), Paris, France Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
INSERM, U1016, Institut Cochin, Paris, France CNRS (UMR 8104), Paris, France Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
J Clin Microbiol. 2014 Jun;52(6):2003-10. doi: 10.1128/JCM.00290-14. Epub 2014 Mar 26.
Streptococcus pyogenes (group A Streptococcus [GAS]) causes a wide variety of diseases, ranging from mild noninvasive to severe invasive infections. Mutations in regulatory components have been implicated in the switch from colonization to invasive phenotypes. The inactivation of the sil locus, composed of six genes encoding a quorum-sensing complex, gives rise to a highly invasive strain. However, studies conducted on limited collections of GAS strains suggested that sil prevalence is around 15%; furthermore, whereas a correlation between the presence of sil and the genetic background was suggested, no link between the presence of a functional sil locus and the invasive status was assessed. We established a collection of 637 nonredundant strains covering all emm genotypes present in France and of known clinical history; 68%, 22%, and 10% were from invasive infections, noninvasive infections, and asymptomatic carriage, respectively. Among the 637 strains, 206 were sil positive. The prevalence of the sil locus varied according to the emm genotype, being present in >85% of the emm4, emm18, emm32, emm60, emm87, and emm90 strains and absent from all emm1, emm28, and emm89 strains. A random selection based on 2009 French epidemiological data indicated that 16% of GAS strains are sil positive. Moreover, due to mutations leading to truncated proteins, only 9% of GAS strains harbor a predicted functional sil system. No correlation was observed between the presence or absence of a functional sil locus and the strain invasiveness status.
化脓性链球菌（A组链球菌[GAS]）可引发多种疾病，从轻度非侵袭性感染到严重侵袭性感染不等。调节成分的突变与从定植表型向侵袭性表型的转变有关。由编码群体感应复合体的六个基因组成的sil位点失活会产生高度侵袭性菌株。然而，对有限数量的GAS菌株进行的研究表明，sil位点的流行率约为15%；此外，虽然有人提出sil位点的存在与遗传背景之间存在相关性，但并未评估功能性sil位点的存在与侵袭状态之间的联系。我们建立了一个包含637株非冗余菌株的集合，这些菌株涵盖了法国存在的所有emm基因型且临床病史已知；其中分别有68%、22%和10%来自侵袭性感染、非侵袭性感染和无症状携带。在这637株菌株中，206株sil呈阳性。sil位点的流行率因emm基因型而异，在emm4、emm18、emm32、emm60、emm87和emm90菌株中，该位点的存在率>85%，而在所有emm1、emm28和emm89菌株中均不存在。基于2009年法国流行病学数据的随机选择表明，16%的GAS菌株sil呈阳性。此外，由于导致蛋白质截短的突变，只有9%的GAS菌株含有预测的功能性sil系统。未观察到功能性sil位点的存在与否与菌株侵袭状态之间存在相关性。
