Group 1 patients will be randomized to nitrofurantoin monohydrate/macrocrystalline 100 mg twice daily for 7 days prior to PCNL with the final day of prophylactic course being 1 day prior to surgery or to nitrofurantoin monohydrate/macrocrystalline 100mg twice daily for 48 hours prior to PCNL. Nitrofurantoin monohydrate/macrocrystalline is currently indicated for the treatment of acute uncomplicated urinary tract infections. Both groups will receive antibiotics the day of surgery—i.e. a dose of ampicillin intravenous (IV) (2 g) and gentamicin intravenous (IV) (5 mg/kg) within 120 minutes of surgery start time. Patients with penicillin allergy will receive vancomycin intravenous (IV) (1 g) instead of ampicillin and patients with gentamicin/aminoglycoside allergy will receive ceftriaxone intravenous (IV) (2 g) instead of gentamicin. Postoperative antibiotics in the absence of sepsis (see definition of sepsis below) will be <24 hours of IV antibiotics.