Urinary tract infection in the impaired host.

In general, defects in phagocytosis and in humoral or cellular immunity do not appear to predispose to the acquisition of UTI but do influence the clinical manifestations and the severity, microbiology, and complications of infection once it is established. The incidence of UTI in immunosuppressed patients other than diabetics or renal transplant recipients is not higher than the incidence in nonimmunosuppressed individuals. The higher frequencies of infection seen in diabetics and in renal transplant recipients correlate best with the duration of bladder instrumentation rather than with glycosuria or immunosuppressive regimen. Neutropenia blunts the clinical manifestations of UTI and predisposes to bacteremia. Use of broad spectrum antibiotics results in alterations in indigenous flora, promotes urinary infections with resistant nosocomial pathogens, and predisposes to fungemia with hematogenous seeding of the urinary tract. Routine screening for detection of asymptomatic bacteriuria and prompt institution of antimicrobial therapy is indicated only in renal transplant recipients within 3 months of their surgery and not in any of the other diseases discussed.