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

## TL;DR

This study explores how Escherichia coli and Pseudomonas aeruginosa interact metabolically in catheter infections, revealing how their growth depends on nutrient conditions.

## Contribution

The study identifies metabolic adaptations and cross-feeding between E. coli and P. aeruginosa in catheter-associated infections under different nutrient conditions.

## Key findings

- P. aeruginosa outgrew E. coli in artificial urine medium, while E. coli dominated in culture broth.
- Metabolite analyses showed cross-feeding and distinct metabolic adaptations between the two species.
- E. coli showed signs of iron limitation in artificial urine medium, unlike P. aeruginosa.

## Abstract

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.

The online version contains supplementary material available at 10.1038/s41598-025-33855-1.