ABSTRACTStaphylococcus aureusis a major cause of chronic respiratory infection in patients with cystic fibrosis (CF). We recently showed thatPseudomonas aeruginosaexhibits enhanced biofilm formation during respiratory syncytial virus (RSV) coinfection on human CF airway epithelial cells (AECs). The impact of respiratory viruses on other bacterial pathogens during polymicrobial infections in CF remains largely unknown. To investigate ifS. aureusbiofilm growth in the CF airways is impacted by virus coinfection, we evaluatedS. aureusgrowth on CF AECs. Initial studies showed an increase inS. aureusgrowth over 24 h, and microscopy revealed biofilm-like clusters of bacteria on CF AECs. Biofilm growth was enhanced when CF AECs were coinfected with RSV, and this observation was confirmed withS. aureusCF clinical isolates. Apical conditioned medium from RSV-infected cells promotedS. aureusbiofilms in the absence of the host epithelium, suggesting that a secreted factor produced during virus infection benefitsS. aureusbiofilms. Exogenous iron addition did not significantly alter biofilm formation, suggesting that it is not likely the secreted factor. We further characterizedS. aureus-RSV coinfection in our model using dual host-pathogen RNA sequencing, allowing us to observe specific contributions ofS. aureusand RSV to the host response during coinfection. Using the dual host-pathogen RNA sequencing approach, we observed increased availability of nutrients from the host and upregulation ofS. aureusgenes involved in growth, protein translation and export, and amino acid metabolism during RSV coinfection.IMPORTANCEThe airways of individuals with cystic fibrosis (CF) are commonly chronically infected, andStaphylococcus aureusis the dominant bacterial respiratory pathogen in CF children. CF patients also experience frequent respiratory virus infections, and it has been hypothesized that virus coinfection increases the severity ofS. aureuslung infections in CF. We investigated the relationship betweenS. aureusand the CF airway epithelium and observed that coinfection with respiratory syncytial virus (RSV) enhancesS. aureusbiofilm growth. However, iron, which was previously found to be a significant factor influencingPseudomonas aeruginosabiofilms during virus coinfection, plays a minor role inS. aureuscoinfections. Transcriptomic analyses provided new insight into how bacterial and viral pathogens alter host defense and suggest potential pathways by which dampening of host responses to one pathogen may favor persistence of another in the CF airways, highlighting complex interactions occurring between bacteria, viruses, and the host during polymicrobial infections.
Recurrent wheezing in neonatal pneumonia is associated with combined infection with Respiratory Syncytial Virus and Staphylococcus aureus or Klebsiella pneumoniae