What is the appropriate first‑line antibiotic for an 84‑year‑old woman presenting with dysuria due to an uncomplicated lower urinary‑tract infection?

First-Line Antibiotic for Uncomplicated Cystitis in an 84-Year-Old Woman

For an 84-year-old woman with dysuria from uncomplicated lower urinary tract infection, prescribe nitrofurantoin 100 mg three times daily for 5 days as first-line therapy. 1, 2

Diagnostic Considerations Before Treatment

• In elderly women, genitourinary symptoms are not necessarily related to cystitis and may represent other conditions 1
• If the diagnosis is unclear based on history alone (dysuria, frequency, urgency without vaginal discharge), perform dipstick analysis to increase diagnostic accuracy 1
• Do not obtain urine culture for straightforward uncomplicated cystitis unless: symptoms fail to resolve by end of treatment, symptoms recur within 4 weeks, or the patient presents with atypical symptoms 1

First-Line Antibiotic Selection

Nitrofurantoin is the preferred first-line agent for the following reasons:

• Demonstrates superior clinical resolution (70%) compared to fosfomycin (58%) at 28 days in a high-quality randomized trial 2
• Shows only 20.2% persistent resistance at 3 months and 5.7% at 9 months, compared to 83.8% persistent resistance for ciprofloxacin 1, 3
• Causes minimal collateral damage to protective vaginal and periurethral microbiota, unlike fluoroquinolones and beta-lactams which promote more rapid UTI recurrence 1, 3
• Dosing: 100 mg three times daily for 5 days 2

Alternative First-Line Options (If Nitrofurantoin Contraindicated)

If nitrofurantoin cannot be used due to renal impairment (CrCl <30 mL/min) or allergy:

• Fosfomycin trometamol 3 g single dose - FDA-approved specifically for uncomplicated cystitis in women, though less effective than nitrofurantoin 1, 4, 2
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days - only if local E. coli resistance is <20% 1, 3

Critical Agents to Avoid

Do not prescribe fluoroquinolones (ciprofloxacin, levofloxacin) for uncomplicated UTI:

• The FDA issued an advisory warning in 2016 that fluoroquinolones should not be used for uncomplicated UTIs due to disabling and serious adverse effects resulting in an unfavorable risk-benefit ratio 1, 3
• High persistent resistance rates (83.8% for ciprofloxacin) 1, 3
• Cause significant collateral damage including C. difficile infection and long-term alterations to fecal microbiota 1, 3
• Not recommended even as second-line agents per current FDA guidance 1, 3

Avoid beta-lactam antibiotics (cephalosporins, amoxicillin-clavulanate):

• Promote more rapid UTI recurrence due to loss of protective periurethral and vaginal microbiota 1, 3
• High persistent resistance rates (54.5% for amoxicillin-clavulanate) 1

Follow-Up Management

• If symptoms persist beyond 7 days or recur within 2 weeks: obtain urine culture and antimicrobial susceptibility testing 1, 3
• Assume the infecting organism is not susceptible to the originally used agent 1, 3
• Retreat with a 7-day regimen using a different antibiotic class based on culture results 1
• Do not perform routine post-treatment urinalysis or urine cultures in asymptomatic patients 1, 3

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria in elderly women - this increases risk of symptomatic infection and bacterial resistance 1, 3
• Do not use longer courses or broader-spectrum antibiotics thinking they are needed for age alone - this promotes resistance and recurrence 1, 3
• Do not perform extensive workup (cystoscopy, full abdominal ultrasound) unless there are specific risk factors or treatment failures 3
• Do not prescribe nitrofurantoin for pyelonephritis - it achieves insufficient tissue levels for upper tract infection 1, 4