New directions in the diagnosis and therapy of urinary tract infections

Abstract

Urinary tract infections are among the most common bacterial infections. To provide appropriate and cost-effective treatment, physicians need to stratify patients with urinary complaints into uncomplicated or complicated categories. This can be accomplished by the history, presenting symptoms, risk factors, and physical examination. Complicated urinary tract infections occur in patients with a history of recurrent infections, signs or symptoms of upper tract disease, or coexisting conditions such as pregnancy, immunosuppression, or structural anomalies of the urinary tract. Uncomplicated urinary tract infections occur in otherwise healthy women who have a history of lower tract symptoms of short duration. Symptoms of urinary tract infection include some combination of dysuria, frequency, urgency, hematuria, and suprapubic pain. An uncomplicated urinary tract infection is not accompanied by fever or flank pain. The microbiology of uncomplicated urinary tract infection is predictable, with Escherichia coli and other Enterobacteriaceae, Staphylococcus saprophyticus, and Enterococcus causing more than 90% of urinary tract infections. A history, brief physical examination, and urinalysis are all that is necessary to diagnose a urinary tract infection. Some of the specialized dipsticks and rapid screens are as accurate as microscopic examination in detecting urine white cells. A presumptive diagnosis can be made when a patient has clinical symptoms and some combination of pyuria, hematuria, or bacteriuria. Urine cultures are unnecessary in uncomplicated urinary tract infections and add substantially to the cost of therapy. Pitfalls in the diagnosis include other entities causing dysuria, such as vaginitis, vulvar lesions, physical or chemical irritants, and sexually transmitted diseases. Appropriate therapy requires selection of a drug and determination of the length of treatment. A minor infection should be treated with easy, safe, cost-effective therapy. For urinary tract infections, there are too many antibiotic options, ranging from a single, parenteral dose to a 14-day course of oral medication. Early optimism about single-dose oral therapy has been replaced by evidence suggesting that 3 days of therapy is probably the best. This will eradicate simple urinary tract infections in virtually all patients and decrease the incidence of relapse, whereas patients who are treatment failures usually have occult upper tract infection. Drug choices for short-course therapy include representatives from the penicillin, sulfa, and quinolone families. Selection of a specific drug requires consideration of costs, allergies, side effects, and spectrum of activity. A knowledge of local microbial sensitivity profiles and individual patient tolerance is helpful in guiding the clinician to the appropriate therapeutic regimen.