Does Macrobid (nitrofurantoin) cover Streptococcus Group B urinary tract infections (UTIs)?

Nitrofurantoin (Macrobid) Coverage for Group B Streptococcus UTIs

Nitrofurantoin (Macrobid) is effective for treating uncomplicated urinary tract infections caused by Group B Streptococcus (GBS). 1

Efficacy Against Group B Streptococcus

• Nitrofurantoin is recommended as a first-line agent for uncomplicated urinary tract infections and has broad-spectrum bactericidal activity against both Gram-positive and Gram-negative pathogens, including Group B Streptococcus 1, 2
• Nitrofurantoin achieves high urinary concentrations that are effective against common uropathogens, making it suitable for treating lower UTIs caused by susceptible organisms including Group B Streptococcus 1
• It is specifically recommended for uncomplicated UTIs due to vancomycin-resistant enterococci (VRE), demonstrating its efficacy against Gram-positive organisms similar to GBS 1

Dosing and Administration

• The recommended dosing for nitrofurantoin in uncomplicated UTIs is:
  • Nitrofurantoin macrocrystals: 50-100 mg four times daily for 5 days 1
  • Nitrofurantoin monohydrate/macrocrystals (Macrobid): 100 mg twice daily for 5 days 1
  • Nitrofurantoin macrocrystals prolonged release: 100 mg twice daily for 5 days 1

Advantages of Nitrofurantoin for UTIs

• Nitrofurantoin maintains high susceptibility rates (>95%) against common uropathogens including E. coli, with low resistance rates (approximately 2.3%) compared to fluoroquinolones (24%) and trimethoprim-sulfamethoxazole (29%) 3
• It has a long history of clinical use (over 35 years) with a good safety profile and minimal development of resistance 4
• Guidelines consistently recommend nitrofurantoin as a first-line agent for uncomplicated UTIs, along with trimethoprim-sulfamethoxazole and fosfomycin 1

Clinical Considerations

• Nitrofurantoin is primarily effective for lower UTIs (cystitis) as it concentrates in the bladder but does not achieve adequate tissue levels for treating upper UTI (pyelonephritis) 1, 5
• A randomized controlled trial demonstrated that nitrofurantoin was significantly more effective than placebo in achieving both bacteriological cure and symptomatic relief in just three days for uncomplicated UTIs 6
• Nitrofurantoin should be used with caution in patients with renal impairment (creatinine clearance <30 mL/min) as reduced renal excretion can lead to decreased urinary concentration and increased risk of toxicity 5

Alternative Options

• If nitrofurantoin cannot be used or if resistance is suspected, alternative first-line agents include:
  • Fosfomycin trometamol: 3g single dose 1
  • Trimethoprim-sulfamethoxazole: 160/800 mg twice daily for 3 days 1
• Second-line options include cephalosporins and fluoroquinolones, but these should be reserved due to concerns about resistance and collateral damage to gut flora 1, 5

Nitrofurantoin remains a valuable antibiotic for treating uncomplicated UTIs, including those caused by Group B Streptococcus, due to its continued effectiveness, low resistance rates, and minimal impact on normal flora compared to broader-spectrum agents 3, 2.