Long-term catheterization of elderly patients results in the development of polymicrobial bacteriuria, that can lead to more serious, even life- threatening, pyelonephritis or bacteremia. The catheter favors development of infection because it provides a colonization site for bacteria that protects them from washout, antibiotic treatment, and host defense. Thus, an understanding of the processes controlling catheter colonization can be used to improve strategies for preventing or controlling catheter- associated urinary tract infection. Studies of surface-colonization by polymicrobial populations in our laboratory have demonstrated that particular species can play key roles in colonization. Thus, this Project will identify organisms or bacterial properties that initiate or enhance bacterial colonization of urinary catheters. To select three organisms for detailed study in mixed-species systems, we shall first screen seven groups of bacteria commonly isolated from urinary tracts of elderly, long-term catheterized patients, i.e. Providencia stuartii, Escherichia coli. Proteus mirabilis, Morganella morganii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and group D streptococci. The following hypotheses will then be tested: (i) bacterial colonization of catheter surfaces is increased by specific, predominant organisms; (ii) colonization in polymicrobial communities can be enhanced by specific cell surface or physiological characteristics, e.g., MR/K and MR/P hemagglutinins, Type 1 and P fimbriae, flagella, or urease production; (iii) Tamm-Horsfall protein influences colonization by binding to bacterial or catheter surfaces or through nutritional effects; (iv) the relative resistance of bacteria on surfaces to antibiotics is due to immobilization of antibiotic by the extracellular polysaccharide matrix or differences in physiological condition of free bacteria and those colonizing surfaces; (v) specific adhesive interactions identified in the laboratory systems are also exhibited in vivo in the catheterized mouse model system (see Core). Techniques will include the use of laboratory model systems simulating urinary tract conditions; identification of species colonizing catheters by differential plating; identification of genotypes expressing cell surface antigens by immuno-fluorescent staining and computer-enhanced microscopy; biochemical determination of biomass as total DNA, protein, and hexose; microautoradiography, and analysis of outer membrane proteins and lipopolysaccharides by polyacryamide gel electrophoresis.

National Institute of Health (NIH)
National Institute on Aging (NIA)
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University of Maryland Baltimore
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