Diagnosis and empiric therapy of urinary tract infection in the seriously ill patient.

Urinary tract infections (UTIs) are the most prevalent serious infections encountered by the typical physician. When these infections are an imminent threat, microscopic urinalysis rapidly provides sensitive and specific diagnostic information that can establish the diagnosis and guide initial therapy. Tests of localization of infection play no important role in early management decisions. The choice of empiric antibiotic therapy depends on the patterns of resistance in the patient's environment. Even when UTIs are nominally community acquired, an important minority of isolates are resistant to first-generation cephalosporins. Thus far the great majority of gram-negative urinary tract isolates have been susceptible to aminoglycosides and to third-generation cephalosporins. Appropriate therapy should promptly eradicate microscopically visible bacteriuria. Failure to do so after a day is presumptive evidence that the antibiotic is ineffective in vivo and is reason to change the antibiotic if the clinical condition warrants this. Conversely, the patient who fails to respond clinically despite eradication of microscopic bacteriuria is unlikely to fare better with a different antibiotic. In this setting, search for an isolated infected focus, such as an abscess, or for sites of dissemination of the infection is more likely to yield a solution.