What is the treatment of choice for an acute urinary tract infection (UTI) in a 66-year-old female?

Treatment of Choice for Acute UTI in a 66-Year-Old Female

First-line therapy for acute uncomplicated UTI in a 66-year-old female should be nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin, with the specific choice dependent on local antibiogram patterns. 1

Diagnostic Approach

Before initiating treatment:

• Obtain urinalysis and urine culture with sensitivity testing to confirm diagnosis and guide therapy
• Document symptoms (dysuria, frequency, urgency, hematuria)
• Rule out vaginal discharge or irritation which may suggest alternative diagnosis

First-Line Treatment Options

Nitrofurantoin

• Dosage: 100 mg twice daily for 5 days
• Advantages: Low resistance rates, minimal collateral damage to gut flora
• Caution: Avoid if CrCl <30 mL/min or signs of pyelonephritis

Trimethoprim-Sulfamethoxazole (TMP-SMX)

• Dosage: 160/800 mg (DS tablet) twice daily for 3 days
• Consider only if local resistance rates <20%
• FDA-approved for urinary tract infections caused by susceptible strains of E. coli, Klebsiella, Enterobacter, Morganella morganii, and Proteus species 2

Fosfomycin

• Dosage: 3 g single dose
• Advantages: Convenient single-dose regimen, good activity against resistant organisms

Treatment Duration

• For uncomplicated UTI in older women, a short course (3-5 days) is generally sufficient 1, 3
• Longer courses (7 days) may be considered for patients with risk factors or comorbidities 4
• Single-dose antibiotics (except fosfomycin) are associated with higher rates of bacteriological persistence and should be avoided 1

Alternative Options

If first-line agents cannot be used due to allergies, resistance, or other contraindications:

• Second-line agents include fluoroquinolones (e.g., ciprofloxacin)
• Reserve these for cases where first-line agents cannot be used due to higher risk of collateral damage (C. difficile infection, selection of resistant organisms) 1

Special Considerations for Older Women

• Obtain urine culture before initiating empiric therapy in women ≥65 years
• First-line antibiotics and treatment durations do not differ from those recommended for younger adults 3
• Consider comorbidities and drug interactions when selecting therapy
• Nitrofurantoin may have lower treatment failure rates but higher risk of adverse effects in older adults compared to alternative antibiotics 5

Follow-up

• If symptoms persist despite appropriate antibiotic therapy, repeat urine culture
• Consider alternative diagnoses if cultures are negative despite persistent symptoms
• Avoid testing or treating asymptomatic bacteriuria

Prevention of Recurrence

For patients with history of recurrent UTIs:

• Increased fluid intake
• Methenamine hippurate (1g twice daily) as non-antibiotic prophylaxis
• For postmenopausal women: consider vaginal estrogen therapy
• Low-dose post-coital antibiotics for UTIs related to sexual activity
• Low-dose daily antibiotics for 6-12 months for UTIs unrelated to sexual activity 1, 6

Common Pitfalls to Avoid

• Treating asymptomatic bacteriuria (except in pregnancy)
• Using broad-spectrum antibiotics unnecessarily
• Prolonged courses of antibiotics (>7 days)
• Surveillance urine testing in asymptomatic patients
• Classifying uncomplicated UTIs as "complicated" leading to unnecessary broad-spectrum antibiotic use 1