Candida on urinary catheters can be more than contamination, patient samples suggest

Candida albicans, a common fungal pathogen, can pose a significant threat beyond mere contamination in patients with urinary catheters, according to research published in Proceedings of the National Academy of Sciences. University of Notre Dame's Ana Flores-Mireles and Felipe Santiago-Tirado discovered how the fungus operates within the bladder, potentially altering the diagnosis and treatment of catheter-associated urinary tract infections (CAUTIs).

The researchers identified a critical protein named Efg1, which acts as a master switch in the fungus's ability to cause disease when the catheter is in place. However, the team was unaware of the specific target genes Efg1 controlled within a catheterized bladder. By sequencing the genetic activity of Candida strains, they identified 75 target genes specifically activated in the bladder environment, 26 of which had not been previously characterized.

To validate their laboratory findings, the researchers analyzed urinary catheters taken from patients with C. albicans, and the fungal gene network observed closely matched that from patient samples. This discovery has important implications for medical practice, as current diagnostic tools often attribute fungal presence on catheters to contamination rather than active infection within the bladder.

The findings demonstrate that Candida albicans is not merely a contaminant, but an active colonizer, and its presence can significantly alter the virulence of the infection. The study also highlights the complex interaction between C. albicans and other bacteria, such as E. coli, on catheters, where the presence of bacteria can reduce the virulence of the fungal pathogen.

This research underscores the need for a more comprehensive approach to diagnosing and treating CAUTIs, considering the polymicrobial nature of infections in hospital settings.