Metabolic interactions between bacterial co-isolates from catheter-associated urinary tract infections

Catheter-associated urinary tract infections (CAUTI) are complex infections often involving multi-species bacteria. Escherichia coli is frequently an early coloniser. Subsequent colonisation by Pseudomonas aeruginosa and coexistence mechanisms between the two strains within urethral catheters is not yet fully understood. In this study, metabolic adaptations between co-isolated clinical E. coli and P. aeruginosa strains were investigated. It was found that P. aeruginosa outgrew E. coli in artificial urine medium (AUM), whereas E. coli dominated in culture broth such as Iso-sensitest. No evidence of direct antagonism was observed. Metabolite analyses revealed distinct metabolite patterns indicating cross-feeding and metabolic adaptations. In AUM, stress-response metabolites were elevated. Additionally, E. coli appeared to experience Fe-limitation in AUM, while the same was not observed for P. aeruginosa. The results highlight the influence of nutrient conditions on processes within mixed biofilms.