A model system for genetic analysis of biofilm formation during catheter-associated urinary tract infections

Abstract number: P1899

Reisner A., Wöran A., Holzer M., Schilcher K., Stabentheiner E., Zechner E.L.

Objectives: Catheter-associated urinary tract infections (CAUTI) are the most frequent nosocomial infections in hospitals and other health care facilities. Catheter insertion in the bladder creates a surface subject to extensive biofilm formation that in turn provides a niche for bacterial growth with inherently increased antibiotic resistance. Despite extensive research using simple biofilm model systems, little is known about the genetic determinants promoting colonization of catheter polymers. We aimed to establish a dynamic model system that allows analysis of molecular factors affecting catheter colonization under conditions mimicking a catheter-associated urinary tract infection.

Methods: Wildtype strains of E. coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis as well as various mutant derivatives that were previously shown to give attenuated biofilm formation in simple laboratory biofilm models were inoculated in a slightly modified model system for a catheterized bladder previously used for studying catheter encrustation (Stickler, et al. (1999) Methods Enzymol 310: 494–501). Models with an inserted all-silicone Foley-catheters (Ch14) were incubated for 1 to 5 days using a constant artificial urine flow of 30 ml/h. Several methods were tested to monitor bladder and catheter colonization including harvest of bacteria followed by determination of colony counts, confocal laser-scanning and electron microscopy, and enzymatic assays revealing microbial activities on the catheters.

Results: All strains formed biofilms on the catheters. Using standardized protocols, bladder and catheter colonization was monitored reproducible over time. We found that the most suitable inoculation strategy to identify mutants attenuated in biofilm formation is to co-inoculate wild-type and mutant strains in an initial ratio of 1:1. Decreased fitness of mutant strains is monitored by shift in the bladder and catheter-colonizing population. The best representation of the biofilm structure formed on the catheter surface was obtained using electron microscopy. Not all mutations that have been shown to give attenuated biofilm formation in simple laboratory biofilm models were also attenuated for catheter colonization in this model mimicking a catheter-associated urinary tract infection.

Conclusion: The presented model system for a catheter-associated urinary tract infection is suitable for application of molecular analysis of catheter colonization.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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