What is the Pathogenesis of urinary tract infection?
Urinary infection usually occurs following colonization of the periurethral area by organisms from the normal gut flora and subsequent ascension of these bacteria into the bladder.
This is facilitated by sexual intercourse in women, by urologic procedures including catheter insertion, or by turbulent urine flow in men with prostate hypertrophy. Vesicoureteral reflux, if present, facilitates the ascension of organisms from the bladder to the kidneys. Rarely, UTI follows hematogenous spread from another source, and may present as kidney abscesses. Indwelling urethral catheters and other urologic devices uniformly acquire a surface biofilm composed of microorganisms growing within an extracellular mucopolysaccharide material that they produce. This biofilm incorporates urine components, such as magnesium and calcium ions, and Tamm Horsfall protein. Organisms persist and multiply within the protected environment provided by this biofilm, where there is restricted diffusion of antibiotics and impaired access of host defenses, such as neutrophils.
