Urinary tract infections (UTIs) are common in females, accounting for over 6 million patient visits to physicians per year in the United States. Cystitis (bladder infection) represents the majority of these infections (see the image below). Related terms include pyelonephritis, which refers to upper urinary tract infection; bacteriuria, which describes bacteria in the urine; and candiduria, which describes yeast in the urine.

Signs and symptoms

Symptoms and signs of UTI in the adult are as follows:

• Dysuria
• Urinary urgency and frequency
• A sensation of bladder fullness or lower abdominal discomfort
• Suprapubic tenderness
• Flank pain and costovertebral angle tenderness (may be present in cystitis but suggest upper UTI)
• Bloody urine
• Fevers, chills, and malaise (may be noted in patients with cystitis, but more frequently associated with upper UTI)

Diagnosis

Diagnostic studies for UTI consist of dipstick, urinalysis, and culture. No imaging studies are indicated in the routine evaluation of cystitis.

Current emphasis in the diagnosis of UTI rests with the detection of pyuria, as follows:

• A positive leukocyte esterase dipstick test suffices in most instances
• In females with clinical findings suggestive of UTI, urine microscopy may be indicated even if the leukocyte esterase dipstick test is negative
• Pyuria is most accurately measured by counting leukocytes in unspun fresh urine using a hemocytometer chamber; more than 10 white blood cells (WBCs)/mL is abnormal

Other findings are as follows:

• Microscopic hematuria is found in about half of cystitis cases
• Low-grade proteinuria is common
• A positive nitrate test is highly specific for UTI, but it occurs in only 25% of patients with UTI

Urine culture remains the criterion standard for the diagnosis of UTI. Consider obtaining urine cultures in patients with probable cystitis if any of the following is present:

• Immunosuppression
• Recent urinary tract instrumentation
• Recent exposure to antibiotics
• Recurrent infection
• Advanced age

Definitions of UTI in women, based on culture results in clean-catch urine specimens, are as follows:

• Cystitis: More than 1000 colony-forming units (CFU)/mL
• Pyelonephritis: More than 10,000 CFU/mL
• Asymptomatic bacteriuria: In a female, more than 100,000 CFU/mL in an asymptomatic individual

Any amount of uropathogen grown in culture from a suprapubic aspirate should be considered evidence of a UTI.

Management

Oral therapy with an empirically chosen antibiotic that is effective against gram-negative aerobic coliform bacteria (eg, Escherichia coli) is the principal treatment intervention in patients with cystitis. The first-choice agents for treatment of uncomplicated acute cystitis in women include the following:

• Nitrofurantoin monohydrate/macrocrystals
• Trimethoprim-sulfamethoxazole (TMP-SMX)
• Fosfomycin

• Empiric antibiotic selection is determined in part by local resistance patterns
• Beta-lactam antibiotics (eg, amoxicillin-clavulanate, cefdinir, cefaclor, cefpodoxime-proxetil) may be used when other recommended agents cannot be used ^{[1, 2]}
• Fosfomycin and nitrofurantoin monohydrate/macrocrystals should be avoided in patients with possible early pyelonephritis ^[1]
• Clinicians may wish to limit use of TMP-SMX, to reduce the emergence of resistant organisms
• Fluoroquinolones are typically reserved for complicated cystitis

• TMP-SMX is given for 3 days
• Fosfomycin is given in a single dose
• Nitrofurantoin monohydrate/macrocrystals is given for 5-7 days
• Beta-lactam agents are given for 3–7-days
• For cystitis in older women or infection caused by Staphylococcus saprophyticus, 7 days of therapy is suggested

• Structural abnormalities (eg, calculi, tract anomalies, indwelling catheter, obstruction)
• Metabolic disease (eg, diabetes, renal insufficiency)
• Impaired host defenses (eg, HIV infection, current chemotherapy, underlying active cancer)