Molecular basis for transmission of Streptococcus pyogenes

化脓性链球菌传播的分子基础

• 批准号: MR/X001962/1
• 负责人: Shiranee Sriskandan
• 金额: $ 95.73万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FX001962%2F1
• 关键词: Molecular; basis; transmission; Streptococcus; pyogenes

Group A streptococcus (Strep A) is a highly lethal bacterium that can cause not only simple sore throats and skin infections, but also more deadly infections such as bloodstream infection and toxic shock. It is a major cause of severe sepsis in people who are otherwise healthy, which is why its effects often seem so devastating. It can also affect women who have recently given birth causing something known as childbed fever, or puerperal sepsis; although very rare, this sadly can result in deaths. Strep A only infects humans, which means that infections almost always result from catching the bacteria from another person. It is believed that throat infections are caught from close contact, by mucus from one person reaching another, or by inhaling large droplets spread from another person close by. Skin infections are believed to result from close contact and touch, particularly when the skin is already broken. This is why precautions such as handwashing, and cleaning surfaces are very important when dealing with vulnerable people who may have wounds, or have recently had a baby.Outbreaks of Strep A occur in hospitals, nurseries, care homes, and prisons; anywhere where people who might be more vulnerable are crowded together. Sometimes these outbreaks carry on, even when precautions like handwashing are being adhered to, or involve people who were never close to one another. This raises the possibility that Strep A might be transmitted in the air, in smaller droplets that can remain in the air for longer than larger droplets. Scarlet fever is another infection caused by Strep A, that mainly affects small children and is very infectious. Recently, we investigated outbreaks of scarlet fever in schools and found evidence in some classrooms that Strep A was indeed present in the air. Many of the otherwise healthy children in the classroom had the same strain of Strep A in their throats, and some were able to cough it out. This means that some outbreaks may indeed be associated with airborne Strep A, and to stop those outbreaks, it may sometimes be necessary to introduce precautions to reduce airborne spread; handwashing alone may not be sufficient. Precautions might include improved ventilation, reducing room occupancy and wearing of masks, similar to what was done at the start of the March 2020 COVID-19 lockdown. Those interventions had a dramatic dampening effect on scarlet fever outbreaks that, at the time, were increasing rapidly. We think some strain types are better at spreading in the air than others. In the UK, we have seen new variants of Strep A emerge that, over a period of 4-5 years, have risen to become dominant. This suggests they have a major advantage over older strain types. Similar to viral variants of COVID-19 that were observed to replace older strain types, we believe that the main basis for advantage will be transmissibility . This project sets out to determine which strains of strep A are most suited to airborne spread and which ones are not, to help public health teams decide how best to deal with an outbreak. The project will also use a technique knowns as TraDIS to try to work out which genes in Strep A allow it to survive in different environments such as 'air', or on different surfaces. This could provide some insight into why bacteria behave differently and might allow us to predict how new clones of bacteria, similar to new variants of COVID19, might behave.

A组链球菌（Strep A）是一种高度致命的细菌，不仅可以引起简单的喉咙痛和皮肤感染，还可以引起更致命的感染，如血流感染和中毒性休克。它是健康人严重败血症的主要原因，这就是为什么它的影响往往看起来如此具有破坏性。它也可能影响最近分娩的妇女，导致产褥热或产后败血症;虽然非常罕见，但不幸的是，这可能导致死亡。链球菌A只感染人类，这意味着感染几乎总是由从另一个人身上感染细菌引起的。据信，咽喉感染是通过密切接触，一个人的粘液到达另一个人，或通过吸入附近另一个人传播的大飞沫而感染的。皮肤感染被认为是由密切接触和触摸引起的，特别是当皮肤已经破损时。这就是为什么在处理可能有伤口或最近刚生过孩子的脆弱人群时，洗手和清洁表面等预防措施非常重要。A型链球菌的爆发发生在医院，托儿所，护理院和监狱;任何可能更脆弱的人拥挤在一起的地方。有时候，这些疫情会持续下去，即使像洗手这样的预防措施得到了遵守，或者涉及到从未接近过彼此的人。这就增加了A型链球菌在空气中传播的可能性，即较小的液滴比较大的液滴在空气中停留的时间更长。猩红热是另一种由A型链球菌引起的感染，主要影响幼儿，传染性很强。最近，我们调查了在学校爆发的猩红热，在一些教室里发现了A型链球菌确实存在于空气中的证据。教室里许多其他健康的孩子喉咙里都有同样的A型链球菌，有些人还能把它咳出来。这意味着一些爆发可能确实与空气传播的A型链球菌有关，为了阻止这些爆发，有时可能需要采取预防措施以减少空气传播;仅仅洗手可能是不够的。预防措施可能包括改善通风、减少房间占用率及佩戴口罩，与二零二零年三月COVID-19封锁开始时所采取的措施类似。这些干预措施对当时迅速增加的猩红热疫情起到了显著的抑制作用。我们认为有些菌株在空气中的传播能力比其他菌株强。在英国，我们已经看到A型链球菌的新变种出现，在4-5年的时间里，已经上升到占主导地位。这表明它们比较老的菌株类型具有重大优势。与观察到的COVID-19病毒变体取代旧的毒株类型类似，我们认为优势的主要基础将是传播性。该项目旨在确定哪些A型链球菌菌株最适合空气传播，哪些不适合，以帮助公共卫生团队决定如何最好地应对疫情。该项目还将使用一种名为TraDIS的技术，试图找出A型链球菌中的哪些基因允许它在不同的环境中生存，如“空气”或不同的表面。这可以提供一些关于为什么细菌行为不同的见解，并可能使我们能够预测类似于COVID 19新变体的新细菌克隆的行为。

项目成果

An assessment of the airborne longevity of group A Streptococcus

• DOI: 10.1099/mic.0.001421
• 发表时间: 2024-01
• 期刊: Microbiology
• 影响因子: 1.5
• 作者: Henry P. Oswin;Evie Blake;A. Haddrell;Adam Finn;S. Sriskandan;J. P. Reid;Alice Halliday;A. Goenka