What is the first‑line oral therapy for an uncomplicated urinary‑tract infection in a woman aged ≥ 65 years with an estimated glomerular filtration rate ≥ 30 mL/min/1.73 m²?

First-Line Treatment for Uncomplicated UTI in Elderly Women

Nitrofurantoin monohydrate/macrocrystals 100 mg orally twice daily for 5 days is the recommended first-line treatment for uncomplicated urinary tract infection in a woman aged ≥65 years with eGFR ≥30 mL/min/1.73 m². 1

Primary Recommendation

• Nitrofurantoin remains the optimal first-line agent because it maintains 95-98% susceptibility against E. coli despite over 60 years of use, causes minimal collateral damage to normal flora, and achieves clinical cure rates of 88-93% in elderly patients 1, 2

• The standard regimen is nitrofurantoin monohydrate/macrocrystals 100 mg orally twice daily for 5 days—this duration balances efficacy with minimizing adverse effects, and extending beyond 5-7 days provides no additional benefit 1, 3

• Age ≥65 years does not require modification of the standard nitrofurantoin dose or duration when eGFR is ≥30 mL/min/1.73 m² 3

Alternative First-Line Options

• Fosfomycin trometamol 3 g as a single oral dose is an acceptable alternative when nitrofurantoin cannot be used, though bacteriological cure rates are modestly lower (78-86% vs 81-92%) 1, 4

• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days should only be used if local E. coli resistance is documented to be <20% and the patient has not received this agent in the preceding 3 months 1, 5

Critical Contraindications to Nitrofurantoin

• Do not use nitrofurantoin if any upper tract involvement is suspected—fever >38°C, flank pain, costovertebral angle tenderness, nausea/vomiting, or systemic symptoms indicate possible pyelonephritis, for which nitrofurantoin does not achieve adequate renal tissue concentrations 1, 3

• Nitrofurantoin is contraindicated when eGFR <30 mL/min/1.73 m² due to reduced efficacy and increased risk of peripheral neuropathy 1, 6

• The patient's eGFR of ≥30 mL/min/1.73 m² makes nitrofurantoin appropriate; the 2015 Canadian study demonstrated that mild-to-moderate reductions in eGFR (median 38 mL/min) did not justify avoidance of nitrofurantoin 6

Agents to Reserve or Avoid

• Fluoroquinolones (ciprofloxacin, levofloxacin) should be reserved for pyelonephritis or complicated UTIs, not uncomplicated cystitis, due to FDA safety warnings (tendon rupture, peripheral neuropathy, aortic dissection) and rising community resistance rates of approximately 24% 1, 5

• Oral β-lactam agents (amoxicillin-clavulanate, cephalosporins) demonstrate inferior efficacy compared to nitrofurantoin for uncomplicated cystitis, with failure rates 15-30% higher, and should only be used when first-line agents are unsuitable 7, 5

• Amoxicillin or ampicillin alone should never be used empirically due to globally high resistance rates 7

Diagnostic Approach

• Urine culture is not routinely required before treatment in elderly women with typical symptoms (dysuria, frequency, urgency, suprapubic pain) and no vaginal discharge 1, 3

• Obtain urine culture with susceptibility testing if the patient has recurrent UTI, treatment failure within 2 weeks, history of resistant organisms, or atypical presentation 1, 3

• Do not treat asymptomatic bacteriuria in elderly patients—antibiotics are indicated only for symptomatic infections 7, 1

Special Considerations for Elderly Patients

• Elderly patients often present atypically with confusion, functional decline, or falls rather than classic dysuria, but the presence of typical UTI symptoms (frequency, urgency, dysuria) in this case supports straightforward treatment 7

• A urine pH >9 together with positive nitrite confirms true bacterial infection rather than asymptomatic bacteriuria and warrants treatment 7

• The median age of 79 years in the Canadian study population demonstrates that nitrofurantoin is both safe and effective in this age group when renal function is adequate 6

Common Pitfalls to Avoid

• Do not prescribe nitrofurantoin for "borderline" upper tract symptoms—any flank pain or low-grade fever warrants a fluoroquinolone or cephalosporin instead 1

• Do not extend nitrofurantoin beyond 5-7 days unless symptoms persist, as longer courses increase adverse event risk without improving efficacy 1, 3

• Do not obtain routine post-treatment urine cultures in asymptomatic patients; cultures are only needed if symptoms persist after therapy or recur within 2 weeks 1