Pseudomonas aeruginosasurface motility and invasion into competing communities enhances interspecies antagonism

Abstract

Chronic polymicrobial infections involvingPseudomonas aeruginosaandStaphylococcus aureusare prevalent, difficult to eradicate, and associated with poor health outcomes. Therefore, understanding interactions between these pathogens is important to inform improved treatment development. We previously demonstrated thatP. aeruginosais attracted toS. aureususing type IV pili-mediated chemotaxis, but the impact of attraction onS. aureusgrowth and physiology remained unknown. Using live single-cell confocal imaging to visualize microcolony structure, spatial organization, and survival ofS. aureusduring coculture, we found that interspecies chemotaxis providesP. aeruginosaa competitive advantage by promoting invasion into and disruption ofS. aureusmicrocolonies. This behavior rendersS. aureussusceptible toP. aeruginosaantimicrobials. Conversely, in the absence of type IV pilus motility,P. aeruginosacells exhibit reduced invasion ofS. aureuscolonies. Instead,P. aeruginosabuilds a cellular barrier adjacent toS. aureusand secretes diffusible, bacteriostatic antimicrobials like 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) into theS. aureuscolonies.P. aeruginosareduced invasion leads to the formation of denser and thickerS. aureuscolonies with significantly increased HQNO-mediated lactic acid fermentation, a physiological change that could complicate the effective treatment of infections. Finally, we show thatP. aeruginosamotility modifications of spatial structure enhance competition againstS. aureus. Overall, these studies build on our understanding of howP. aeruginosatype IV pili-mediated interspecies chemotaxis mediates polymicrobial interactions, highlighting the importance of spatial positioning in mixed-species communities.