What is the recommended treatment for a patient with an uncomplicated urinary tract infection using Nitrofurantoin (macrocrystals)?

Nitrofurantoin Macrocrystals for Uncomplicated UTI

For uncomplicated urinary tract infections in women, prescribe nitrofurantoin macrocrystals 100 mg orally twice daily for 5 days, which achieves 84-93% clinical cure rates and is recommended as first-line therapy by the IDSA and ESMID. 1, 2

Standard Dosing Algorithm

For Women with Uncomplicated Cystitis

• Prescribe 100 mg orally twice daily for 5 days as the optimal regimen 1, 2
• This achieves clinical cure rates of 84-90% and bacterial cure rates of 92% at early follow-up 2
• The 5-day regimen is equivalent to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days 1
• A 7-day course (100 mg twice daily) is acceptable if preferred, with clinical cure rates of 89-93% 2

For Men with Uncomplicated UTI

• Prescribe 100 mg orally twice daily for 7 days (men require longer duration than women) 3
• Expected clinical cure rates remain 88-93% with the extended duration 3

For Pediatric Patients

• Children ≥12 years: Use adult dosing of 100 mg twice daily 2
• Children <12 years: Use 5-7 mg/kg/day divided into 4 doses (maximum 100 mg/dose) for 7 days 1, 2

Critical Contraindications to Check Before Prescribing

Always check renal function before prescribing—this is the most dangerous error to avoid. 3

• Do NOT prescribe if creatinine clearance <60 mL/min (FDA contraindication due to inadequate urinary drug concentrations and increased toxicity risk including peripheral neuropathy) 3, 2
• Do NOT use if early pyelonephritis is suspected (nitrofurantoin does not achieve adequate tissue concentrations for upper tract infections) 1, 2
• Contraindicated in the last trimester of pregnancy 4

When to Choose Alternative First-Line Agents

If nitrofurantoin cannot be used, select alternatives based on this hierarchy:

• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days if local E. coli resistance <20% 1, 2
• Fosfomycin trometamol 3 g single dose (slightly lower efficacy: 90% vs 95% for nitrofurantoin) 1, 2
• Pivmecillinam 400 mg twice daily for 5 days where available 1

Avoid fluoroquinolones as first-line therapy—reserve them for more invasive infections due to resistance concerns and collateral damage 1, 5

Expected Adverse Effects and Monitoring

• Nausea and headache are most common, occurring in 5.6-34% of patients (comparable to trimethoprim-sulfamethoxazole at 31-38%) 1, 2
• Monitor for peripheral neuropathy, pulmonary reactions, and hepatotoxicity, especially in patients with borderline renal function 3
• Ensure adequate hydration during treatment to prevent crystal formation 1

Follow-Up Recommendations

• Do NOT order routine post-treatment cultures if the patient is asymptomatic 1, 3
• Obtain urine culture with susceptibility testing if symptoms persist or recur within 2 weeks 1, 3
• If retreatment is needed, assume resistance to the original agent and use a different antibiotic for 7 days 3

Special Populations

Elderly Patients

• Check renal function before prescribing (CrCl must be ≥60 mL/min) 3
• Expert consensus specifically recommends avoiding nitrofurantoin in older adults with CrCl <30 mL/min 3

Patients with Diabetes

• Women with diabetes without voiding abnormalities should be treated similarly to women without diabetes 5
• Be aware that antimicrobial and clinical efficacy may be reduced in patients with complicating factors like diabetic polyneuropathy 6

VRE (Vancomycin-Resistant Enterococcus) UTIs

• Use higher dosing: 100 mg orally four times daily 1, 2

Common Pitfalls to Avoid

• Never prescribe without checking renal function first—this is the single most dangerous error 3
• Avoid 3-day regimens (100 mg four times daily) due to lower efficacy (only 88% clinical cure and 74% bacterial cure) 2
• Do not use for complicated UTIs or suspected pyelonephritis—inadequate tissue penetration 3
• Do not extend treatment beyond 7 days unless symptoms persist—shorter courses minimize adverse effects while maintaining efficacy 1