Hiding within the Human Host - Persistence and Resistance Strategies by Gram-positive Bacteria in Severe Necrotizing Skin and Soft Tissue Infections

该项目的重点是由革兰氏阳性菌引起的严重急性感染：A组和G组链球菌（GAS; GGS）和耐甲氧西林金黄色葡萄球菌（MRSA）。这些微生物与各种疾病有关，从浅表皮肤和咽喉感染到危及生命的败血症、中毒性休克综合征和坏死性软组织感染（NSTI）。后者是迅速进展的感染，尽管及时使用抗生素和重症监护，但死亡率和发病率仍很高。我们最近的研究结果表明，有（i）大量的生物膜形成的软组织和（ii）遗传和表型适应的细菌在NSTI。这开辟了一条新的研究路线，重点是在组织部位的持久性和抗性表型。我们认为，细菌的持久性代表了疾病严重程度的一个关键决定因素，导致与持续的毒力因子产生和组织病理学相关的重要水库。NSTI通常需要广泛的组织清创术或甚至截肢术，并且它们与大量死亡率相关。这些感染是全球日益严重的健康问题。我们将应用组织工程来产生体外皮肤，这将使我们能够研究组织部位的细菌持久性/耐药性表型，包括细菌的表型转换和生物膜形成，这在急性NSTI中几乎是未探索的主题。此外，我们将对大组织活检材料中的细菌载量进行全面分析，并将其与患者记录（治疗、结局等）相关联。此外，我们将确定（i）潜在的毒力机制和治疗靶点，以及（ii）导致感染严重程度的宿主途径。关于严重非传染性感染的数据很少，需要进行更多的调查。拟议项目的预期影响是广泛的，涉及几个方面，包括（i）对严重皮肤和软组织感染的病理生理学的新见解和（ii）用于组织中细菌耐药表型研究的新型上级实验系统。

This project focuses on severe acute infections caused by Gram-positive bacteria: group A and G streptococci (GAS; GGS) and methicillin-resistant Staphylococcus aureus (MRSA). These microorganisms are associated with a variety of diseases ranging from superficial skin and throat infections to life-threatening sepsis, toxic shock syndrome and necrotizing soft tissue infections (NSTIs). The latter are rapidly progressing infections associated with high mortality and morbidity despite prompt antibiotics and intensive care. Our recent findings suggest that there is (i) a substantial biofilm formation in the soft tissue and (ii) genetic and phenotypic adaptation of the bacteria during NSTIs. This opens up a novel line of research focusing on persistence and resistance phenotypes at the tissue site. We believe that bacterial persistence represents a key determinant of disease severity resulting in a significant reservoir associated with a sustained virulence factors production and tissue pathology. NSTIs often require extensive tissue debridement or even amputation, and they are associated with substantial mortality. These infections represent an increasing health problem globally. We will apply tissue engineering to generate in vitro skin, which will allow us to study bacterial persistence/resistance phenotypes at the tissue site including phenotypic switches of the bacteria and biofilm formation, virtually unexplored topics in acute NSTIs. In addition, we will conduct comprehensive analyses of bacterial load in the large tissue biopsy material and relate them to the patient records (treatment, outcome etc.). Further, we will identify (i) potential virulence mechanisms and therapy targets and (ii) host pathways contributing to the severity of infection. The data on severe NSTIs is sparse and requires more investigations. The expected impact of the proposed project is broad and involves several aspects, including (i) novel insight into the pathophysiology of severe skin and soft tissue infections and (ii) a novel experimental system superior for studies of bacterial resistance phenotypes in tissue.