The Host Immune System Facilitates Disseminated Staphylococcus aureus Disease Due to Phagocytic Attraction to Candida albicans During Co-infection: A Case of Bait and Switch.

Invasive Staphylococcus aureus infections account for 15–50% of fatal bloodstream infections annually. These disseminated infections often arise without a defined portal of entry into the host, but cause high rates of mortality. The fungus Candida albicans and Gram-positive bacterium S. aureus can form polymicrobial biofilms on epithelial tissue facilitated by the C. albicans adhesin ALS3. While bacterium-fungus interaction is required for systemic infection, the mechanism by which bacteria disseminate from epithelium to internal organs is unclear. In this study, we show that highly immunogenic C. albicans hyphae attract phagocytic cells, which rapidly engulf adherent S. aureus and subsequently migrate to cervical lymph nodes. Following S. aureus-loaded phagocyte translocation from the mucosal surface, S. aureus produces systemic disease with accompanying morbidity and mortality. Our results suggest a novel role for the host in facilitating bacteria-fungal infectious synergy, leading to disseminated staphylococcal disease.