Abstract

Biofilms are an important medical burden, notably for patients with orthopaedic device-related infections. When polymicrobial, these infections are more lethal and recalcitrant. Inter-kingdom biofilm infections are poorly understood and challenging to treat. Here, an in vitro three-species model including Staphylococcus aureus, Escherichia coli and Candida albicans was developed, to represent part of the diversity observed in orthopaedic infections or other clinical contexts. The importance of fungal hyphae for biofilm formation and virulence factor expression was explored. Two protocols were set up, allowing, or not, for hyphal formation. Culturable cells and biomass were characterised in both models, and biofilms were imaged in bright-field, confocal and electron microscopes. The expression of genes related to virulence, adhesion, exopolysaccharide synthesis and stress response was analysed in early-stage and mature biofilms. It was found that biofilms enriched in hyphae had larger biomass and showed higher expression levels of genes related to bacterial virulence or exopolysaccharides synthesis.

摘要

生物膜是一种重要的医疗负担，特别是对于骨科器械相关感染的患者。当使用多种微生物时，这些感染会更加致命和顽固。跨界生物膜感染知之甚少，治疗具有挑战性。在这里，一个包括金黄色葡萄球菌、大肠杆菌和白色念珠菌的体外三物种模型开发，以代表在骨科感染或其他临床环境中观察到的多样性的一部分。探讨了真菌菌丝对生物膜形成和毒力因子表达的重要性。建立了两个协议，允许或不允许菌丝形成。两种模型都表征了可培养细胞和生物量，并且在明场、共聚焦和电子显微镜下对生物膜进行了成像。在早期和成熟的生物膜中分析了与毒力、粘附、胞外多糖合成和应激反应相关的基因的表达。结果表明，富含菌丝的生物膜具有更大的生物量，并且与细菌毒力或胞外多糖合成相关的基因表达水平更高。