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Cystic Fibrosis (CF) is a genetic disorder characterized by faulty ion channels and result in thick mucus accumulation, especially in lungs. Mucus buildup provides ideal conditions for bacterial infections. Pseudomonas aeruginosa (PA) is the second most prevalent bacterium isolated from people with CF and has a high clinical importance. Most CF pathogens form biofilms which make treatment of infections difficult. Biofilms are clusters of cells attached to a surface enclosed in a structured matrix. These structures are a means to provide shelter for bacteria from the environment, especially antibiotics and the immune system. PA alone can form these biofilms, but communities of different bacterial species can also form biofilms together. Multispecies biofilms can form beneficial or antagonistic relationships with PA. In this study, we investigated the interaction between PA and two other important CF pathogens, Staphylococcus aureus (SA) and Burkholderia cenocepacia (BC). SA is the most prevalent CF pathogen and BC is arguably the most fatal. We tested the survival of these species in groups or alone in various nutrient conditions and in differing tobramycin concentrations. We chose tobramycin because it is an antibiotic commonly prescribed to treat PA infections. Our results show that nutrient composition, antibiotic concentration, and time all had a significant effect on the interactions between PA mono-culture and co-cultured biofilms. Understanding these interactions may set the stage for a better understanding of the clinical course of infection and how treatments can be altered for multi-species infections.

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Cystic Fibrosis, Biofilms, Pseudomonas aeruginosa, Nutrient Availability


Biology | Microbiology | Pathogenic Microbiology

The Effects of Nutrient Availability on Pseudomonas aeruginosa Mono and Co-culture Biofilms