What is the recommended treatment for a urinary tract infection (UTI) in a 91-year-old woman with normal renal function?

UTI Treatment in a 91-Year-Old Woman

For a 91-year-old woman with normal renal function and a urinary tract infection, nitrofurantoin 100 mg twice daily for 5 days is the recommended first-line treatment. 1

First-Line Treatment Options

For elderly women with normal renal function, the following first-line options are appropriate:

• Nitrofurantoin 100 mg twice daily for 5 days (preferred)
• Fosfomycin trometamol 3 g single dose
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (if local resistance rates <20%)

Diagnostic Approach

Before initiating treatment:

• Obtain urinalysis and urine culture with sensitivity testing
• Avoid treating asymptomatic bacteriuria, which is common in elderly patients
• Confirm presence of UTI symptoms (dysuria, frequency, urgency, suprapubic pain)
• Rule out vaginal atrophy which can mimic UTI symptoms in elderly women

Treatment Algorithm

1. Empiric therapy: Start with nitrofurantoin if renal function is normal
2. Adjust based on culture: Modify treatment if resistance is identified
3. Duration: Complete 5-day course for uncomplicated cystitis
4. Follow-up: No routine post-treatment cultures needed if symptoms resolve

Special Considerations for Elderly Women

• Renal function: Despite traditional concerns, nitrofurantoin can be used in patients with eGFR >30 mL/min 2
• Avoid fluoroquinolones: Use as second-line only due to risk of adverse effects and increasing resistance 1
• Vaginal estrogen: Consider as adjunctive therapy in postmenopausal women to prevent recurrence 1
• Hydration: Ensure adequate fluid intake to help flush bacteria from the urinary tract

Prevention of Recurrence

If the patient experiences recurrent UTIs (≥3 per year):

• Methenamine hippurate 1g twice daily as non-antibiotic prophylaxis
• Vaginal estrogen in postmenopausal women (strong recommendation)
• Increased fluid intake
• Proper hygiene practices

Cautions and Pitfalls

• Avoid treating asymptomatic bacteriuria: Common in elderly women and treatment increases resistance 3, 1
• Avoid classifying as "complicated" UTI based solely on age, as this often leads to unnecessarily broad-spectrum antibiotics and longer treatment durations 3
• Monitor for adverse effects: Particularly with nitrofurantoin, which can rarely cause pulmonary reactions with prolonged use 4
• Repeat urine culture if symptoms persist despite treatment before prescribing additional antibiotics 3

When to Consider Hospitalization

Consider hospitalization if:

• Signs of systemic infection (fever >38°C, hypotension)
• Inability to tolerate oral medications
• Concern for pyelonephritis (flank pain, fever, nausea/vomiting)
• Dehydration or altered mental status

By following these evidence-based recommendations, UTIs in elderly women can be effectively managed while minimizing antibiotic resistance and adverse effects.