Urinary Tract Infection: Diagnosis and Treatment

The diagnosis of acute cystitis can usually be made by history. Acute onset of dysuria, urinary frequency, and absence of vaginal symptoms usually warrant empiric treatment. A urine dip or urinalysis (of a sample collected midstream) is an inexpensive way to help confirm suspicion, where leukocytes, red blood cells, and/or nitrites may be noted.

Urine culture is not indicated in an uncomplicated bladder infection, unless resistance to standard antibiotic therapies is likely. In complicated and recurrent infections, a urine culture and sensitivity should be done. Blood cultures should be performed if pyelonephritis is suspected, because bacteremia is present in about one third of cases.

Persons with recurrent or refractory infections may need diagnostic testing for an anatomic abnormality. This may include a spiral CT scan for kidney stones, intravenous pyelogram, cystogram, and cystoscopy.

Treatment

Asymptomatic bacteriuria does not necessarily require treatment. However, therapy is advisable in the context of advanced age, pregnancy, male gender, immunocompromise, structural abnormalities, kidney stones, pyelonephritis, or urinary symptoms.

Uncomplicated cases of urinary tract infection usually require a 3– to 7–day course of antibiotic therapy. A longer course of antibiotics may be necessary for patients with a history of UTI, immunocompromise, diabetes, or prolonged symptoms. For chronic UTI, treatment lasting 6 months or more, along with prophylactic antibiotics, may be needed.

Empiric Treatment for Uncomplicated UTI

Nitrofurantoin, used for 7 days, is an effective treatment, and bacterial resistance is rare.

Trimethoprim/sulfamethoxazole (TMP/SMX) combinations are appropriate for empirical therapy (1– to 3–day course), but prevalence of resistant bacteria is increasing.

Fluoroquinolones are less appropriate for empiric therapy because of their broad–spectrum of bacterial coverage. In TMP/SMX–resistant bacteria, resistance to fluoroquinolones occurs more frequently than to nitrofurantoin.²

Uncomplicated UTI

Treatment based on culture and sensitivity will likely include one of the above drug classes. Cost–effective therapy with the narrowest spectrum agent should be used.

Other possible antibiotics include sulfonamides, trimethoprim, and cephalosporins.

Amoxicillin and doxycycline are used to treat sexually transmitted urethritis. Sexual partners should be treated as well. Note: Standard urine cultures may be negative in Chlamydia–caused urethritis.

Complicated UTI

Fluoroquinolones (except for moxifloxacin) are first–line empiric agents.

Nitrofurantoin is not an appropriate empiric therapy.

Treatment usually is needed for 1 to 2 weeks, and may require hospitalization and pathogen–focused drugs.

Pyelonephritis

Uncomplicated pyelonephritis is best treated with TMP/SMX for 14 days.

Complicated pyelonephritis will require hospitalization and pathogen–focused IV antibiotics. These include ampicillin and gentamicin, TMP/SMX, fluoroquinolones, or third–generation cephalosporins.

Other

In men, all UTIs should be considered complicated. Fluoroquinolones should be used as first–line agents for a longer–than–normal treatment course.

Various prophylactic regimens, such as TMP/SMX, nitrofurantoin, and cranberry or other supplements, may help recurrent UTIs.³

Phenazopyridine (Pyridium) is an analgesic that can be used for severe dysuria. It may turn the urine orange or red, and give a false positive nitrite test because of the discolored urine.