Air pollution induces an adaptive response in Staphylococcus aureus and alters host-pathogen interaction

Air pollution is a major global health problem, with around 91% of the world’s population living in areas that exceed the WHO air pollution guidelines. This complex mix of pollutants almost always includes particulate matter (PM), and this has the greatest impact on human health. PM exposure contributes to a range of diseases such as COPD, heart disease and respiratory infections. Our recent publication was the first to document that as well as damaging the host, PM has a direct impact on bacteria that can cause respiratory infections. We showed that Black Carbon (BC) exposure results in species-specific alterations in biofilm structure in both Streptococcus pneumoniae and Staphylococcus aureus, altered biofilm protectivity against antibiotic exposure, and S. pneumoniae bacterial colonisation in vivo. Following on from this ground-breaking work, our current data show that the bacterial response to BC occurs at the genetic level, altering the transcription of key genes involved in biofilm formation, colonisation and virulence. Bacterial adhesion to and invasion of human epithelial cells is significantly increased when S. aureus are pre-exposed to BC prior to infection compared to naïve S. aureus cells. In a murine respiratory colonisation model, both S. aureus co-infected alongside BC, and crucially S. aureus pre-exposed to BC, show increased colonisation of the nasopharynx and lungs. These data suggest that the bacteria are responding and adapting to exposure to air pollution, and this has an impact on how the bacteria infect the host.