Pathogenesis of urinary tract infections: an update.

The pathogenesis of uncomplicated urinary tract infection (UTI) is complex and influenced by many host biological and behavioural factors and by properties of the infecting uropathogens. Most uncomplicated UTIs in women are not associated with underlying functional or anatomical abnormalities of the urinary tract, whereas sexual intercourse, spermicide use, a history of recurrent UTI and recent antimicrobial chemotherapy are important risk factors. A maternal history of UTI and young age at first UTI, as well as sexual intercourse and spermicide use, are risk factors for recurrent UTI in young women. In some young healthy women, especially those with 'low UTI risk' behaviour, features of pelvic anatomy appear to be associated with UTI risk. In postmenopausal women, anatomical and functional characteristics of the genitourinary tract are more strongly associated with UTI risk than in younger women. A genetic predisposition to recurrent UTI is suggested by the association of recurrent UTI in certain age groups with the ABH blood group non-secretor phenotype, a maternal history of UTI and early age at onset of UTI. Virulence determinants of uropathogens are much more important in the normal host than in the host who has a functional or anatomical abnormality of the genitourinary tract.