What is the recommended dosing of Macrobid (Nitrofurantoin) for a pre-operative adult patient with a urinary tract infection (UTI) caused by Escherichia coli (E. coli), with a urine culture showing >100,000 colony-forming units per milliliter (CFU/mL) and susceptibility to Nitrofurantoin, and normal renal function?

Nitrofurantoin (Macrobid) Dosing for Pre-Operative UTI

For your pre-operative patient with E. coli UTI susceptible to nitrofurantoin, treat with nitrofurantoin 100 mg orally twice daily for 7 days, starting immediately to allow adequate time for bacterial clearance before surgery. 1

Rationale for Treatment Duration

• Pre-operative UTI treatment requires completion before surgery to prevent post-operative infectious complications including bacteremia and sepsis, which occurred in 5.6% of untreated patients undergoing urologic procedures versus minimal rates in treated patients. 1

• Short-course therapy (1-2 doses) is only appropriate for asymptomatic bacteriuria immediately before endoscopic urologic procedures with mucosal trauma (e.g., TURP, ureteroscopy), not for symptomatic UTI or procedures days away. 1

• Your patient has symptomatic bacteriuria (>100,000 CFU/mL E. coli) requiring full treatment course rather than prophylactic dosing. 1

Specific Dosing Regimen

• Nitrofurantoin macrocrystalline (Macrobid) 100 mg orally twice daily for 7 days is the standard treatment regimen for uncomplicated UTI caused by susceptible E. coli. 2, 3

• Alternative dosing of 100 mg three times daily for 7 days showed 85.3% cure rates versus 93.9% with four times daily dosing, though twice daily is standard for macrocrystalline formulation. 3

• Nitrofurantoin maintains 95.6% susceptibility rates against E. coli with only 2.3% resistance, making it superior to fluoroquinolones (24% resistance) and trimethoprim-sulfamethoxazole (29% resistance). 4

Timing Considerations for Surgery

• Complete the 7-day course before surgery to ensure bacterial eradication, as breakthrough infections during prophylaxis were mostly due to inadequate treatment duration. 5

• Verify clinical response within 48-72 hours and consider repeat urine culture 7-9 days after starting therapy to confirm microbiological clearance before proceeding with surgery. 2

• If surgery cannot be delayed for full treatment course, antimicrobial prophylaxis should be administered 30-60 minutes before the procedure using an agent active against the cultured organism (in this case, ceftriaxone, ciprofloxacin, or levofloxacin based on susceptibilities). 1

Important Clinical Considerations

• Nitrofurantoin achieves urine concentrations approximately 100-fold higher than plasma concentrations, making it highly effective for urinary tract infections but inappropriate for systemic infections or pyelonephritis. 6

• Macrocrystalline formulation (Macrobid) has superior tolerability compared to microcrystalline formulation, with significantly fewer adverse events (13% versus 25.6% premature discontinuation). 5

• Nausea is the most common adverse effect, occurring more frequently with higher doses or microcrystalline formulations. 5

• Ensure adequate renal function before prescribing, as nitrofurantoin is contraindicated in patients with creatinine clearance <60 mL/min due to inadequate urine concentrations and increased risk of toxicity. 4

Alternative Considerations Based on Susceptibilities

• Ceftriaxone or fluoroquinolones (ciprofloxacin/levofloxacin) are alternatives if nitrofurantoin cannot be used, given your organism's susceptibility pattern showing sensitivity to all three agents. 1

• Avoid cefazolin despite "S" notation for uncomplicated urine as the organism shows resistance (R 16) to standard cefazolin dosing for systemic infections. 1