This older adult patient most likely has cystitis and should begin nitrofurantoin therapy. Although the most common symptoms of cystitis in premenopausal women are dysuria, frequency, urgency, and suprapubic discomfort, postmenopausal women with cystitis may experience incontinence. Fever is unusual. The urine dipstick reveals pyuria and bacteriuria with positivity for leukocyte esterase and nitrites, respectively. With her symptoms and positive results on urine dipstick, cystitis is highly likely. Urinary tract infection (UTI) is one of the most commonly diagnosed infections in older adults, and Escherichia coli is the most frequently isolated organism. In one study, E. coli accounted for more than 80% of UTIs in this population. The treatment of cystitis in older adults who do not have significant concurrent medical illnesses is the same as that used in younger patients. This patient should begin nitrofurantoin, 100 mg twice daily for 5 days. Nitrofurantoin should not be used in patients whose creatinine clearance is less than 50 mL/min. Trimethoprim-sulfamethoxazole, one double-strength tablet twice daily for 3 days, is first-line therapy in the absence of a sulfa allergy and if local E. coli resistance to trimethoprim-sulfamethoxazole is less than 20%. Most women with lower UTI have only a superficial mucosal infection and can be cured with short courses of therapy. The advantages of short-course therapy include better adherence, lower cost, fewer adverse effects, and less selective pressure for the emergence of resistant organisms. Three days of therapy is considered superior to single-dose therapy. Nitrofurantoin for 5 days demonstrates better efficacy than a 3-day course of this medication. Treatment is indicated because this patient is symptomatic. If she were asymptomatic, treatment would not be indicated.

Fluoroquinolones, such as levofloxacin and ciprofloxacin, are considered second-line therapy because of their higher cost and the concern for emergence of resistance with widespread use.

A urine culture is indicated if pyelonephritis, complicated UTI, recurrent UTI, multiple antibiotic allergies, or a resistant organism is suspected; in pregnant women with asymptomatic bacteriuria; and for patients undergoing urologic procedures. Urine cultures are not generally indicated to diagnose cystitis.