Host-Parasite Interaction in the Urinary Tract

The term urinary tract infection (UTI) describes a heterogeneous group of disorders localized to the urinary tract [1]. Bacteriuria may be associated with clinical conditions of varying severity and consequence. The analysis of these conditions may be based on several factors. (7) The site of infection: the localization of bacteria to the kidneys can be determined (e.g., by urethral catheterization or bladder wash-out) or implied by a decrease in renal function (e.g., the renal concentrating capacity) [1-3]. (2) The severity of the host response to bacteriuria: the response may be systemic (involving sites distant to the urinary tract, as shown by the elevation of body temperature and circulating acute-phase reactants) and/or local to the urinary tract (as shown by leukocyte excretion) [4, 5]. (3) The consequences of UTI: these include recurrences of UTI and renal scars (which may or may not have consequences for renal function) [6,7] and end-stage renal disease. The link between UTI and renal failure remains, however, undefined. The complexity of UTI has contributed to its usefulness as a model system for studies of pathogenesis. The changes induced in the host by bacteria that enter this normally sterile site may be used to assess determinants of bacterial virulence and host resistance. This approach has provided new insights into the molecular mechanisms that determine the disease process [8].