Environmental acquisition of ST398 Staphylococcus aureus by patients with chronic respiratory disease

Staphylococcus aureus is a major human pathogen and a leading bacterial cause of death worldwide. Some S.aureus lineages including ST398 commonly infect livestock but are rare in humans. These livestock-associated bacteria commonly acquire tetracycline resistance from the use of antibiotics for animal production.Recently we discovered that over 5% of patients with cystic fibrosis (CF) are infected with ST398 S. aureussuggesting that this livestock-associated lineage has jumped into the human population. It is not clear howthese patients developed ST398 infections. The goal of this research project is to determine whether theseST398 infections persist in people with CF and to identify potential environmental sources such as food orwater are the sources of these infections. We hypothesize that ST398 infections persist for 3 years in half ofpatients who become infected. We also hypothesize that ST398 infections are acquired indirectly fromlivestock through either contaminated water supply or from the food supply chain. We will test thesehypotheses by prospectively collecting both clinical and environmental isolates of S. aureus and genomesequencing isolates that are tetracycline resistant a common marker of this lineage. We will use phylogeneticand geospatial analysis to rigorously examine the relationship between strains of ST398 that infect patientswith CF and that are found in water collected around the state of Iowa bioaerosols collected near animalproduction facilities or meat collected from local grocery suppliers.