This study investigates microbial co-occurrences on catheters from long-term catheterized patients. Researchers analyzed 366 catheter and urine samples from 55 patients over one year, identifying 13 positive and 13 negative genus co-occurrences. The results show that many patients have similar microbial species composition across collection periods. The most frequently sampled bacteria, Escherichia coli and Enterococcus faecalis, co-localize on catheter samples. Co-culture experiments revealed that E. coli significantly enhances E. faecalis growth in artificial urine medium. These findings suggest that targeting mechanisms promoting positive co-associations could help treat polymicrobial catheter-associated urinary tract infections (CAUTIs). CAUTIs are a significant healthcare-associated infection, with 1 in 31 hospitalized patients developing one. They are often caused by uropathogenic Escherichia coli, but also by other pathogens like Candida, Enterococcus, and Pseudomonas. The risk of catheter colonization increases with time, and antibiotic resistance is a growing concern. Polymicrobial colonization is common, with 31–87% of catheters and urine samples containing two or more species. Understanding the interactions between these bacteria is crucial for developing new treatments. The study found that 80% of samples were polymicrobial, but most contained only 2–3 species. Positive co-occurrences were observed between species like Proteus and Providencia, Klebsiella and Pseudomonas, and Candida and Serratia. Negative co-occurrences were mainly between Staphylococcal species and Gram-negative bacteria. The results suggest that the urinary tract environment plays a significant role in bacterial interactions. The study also found that E. faecalis and E. coli co-localize on catheters and that E. coli enhances E. faecalis growth in artificial urine medium. This suggests that targeting these interactions could help treat CAUTIs. The study highlights the importance of understanding microbial interactions in the urinary tract to develop effective treatments for polymicrobial infections.This study investigates microbial co-occurrences on catheters from long-term catheterized patients. Researchers analyzed 366 catheter and urine samples from 55 patients over one year, identifying 13 positive and 13 negative genus co-occurrences. The results show that many patients have similar microbial species composition across collection periods. The most frequently sampled bacteria, Escherichia coli and Enterococcus faecalis, co-localize on catheter samples. Co-culture experiments revealed that E. coli significantly enhances E. faecalis growth in artificial urine medium. These findings suggest that targeting mechanisms promoting positive co-associations could help treat polymicrobial catheter-associated urinary tract infections (CAUTIs). CAUTIs are a significant healthcare-associated infection, with 1 in 31 hospitalized patients developing one. They are often caused by uropathogenic Escherichia coli, but also by other pathogens like Candida, Enterococcus, and Pseudomonas. The risk of catheter colonization increases with time, and antibiotic resistance is a growing concern. Polymicrobial colonization is common, with 31–87% of catheters and urine samples containing two or more species. Understanding the interactions between these bacteria is crucial for developing new treatments. The study found that 80% of samples were polymicrobial, but most contained only 2–3 species. Positive co-occurrences were observed between species like Proteus and Providencia, Klebsiella and Pseudomonas, and Candida and Serratia. Negative co-occurrences were mainly between Staphylococcal species and Gram-negative bacteria. The results suggest that the urinary tract environment plays a significant role in bacterial interactions. The study also found that E. faecalis and E. coli co-localize on catheters and that E. coli enhances E. faecalis growth in artificial urine medium. This suggests that targeting these interactions could help treat CAUTIs. The study highlights the importance of understanding microbial interactions in the urinary tract to develop effective treatments for polymicrobial infections.