Effectiveness of Macrobid (Nitrofurantoin) Against Staphylococcus saprophyticus
Macrobid (nitrofurantoin) is effective against Staphylococcus saprophyticus and is recommended as a first-line treatment for uncomplicated urinary tract infections where this pathogen is commonly found. 1, 2
Efficacy Against S. saprophyticus
Nitrofurantoin demonstrates good activity against several common uropathogens, including:
- Escherichia coli (most common UTI pathogen)
- Staphylococcus saprophyticus (second most common cause of UTIs in women)
- Enterococcus species 2
Despite its long-term use since the 1950s, nitrofurantoin has maintained its effectiveness against S. saprophyticus, which is particularly important as resistance to other antibiotics increases 2, 3.
Treatment Recommendations
The American Urological Association and other guideline bodies recommend nitrofurantoin as a first-line antibiotic for uncomplicated UTIs 1. The standard dosing regimen is:
| Agent | Dose | Duration |
|---|---|---|
| Nitrofurantoin | 100mg twice daily | 5 days |
This recommendation is supported by high-quality evidence (level I) 1.
Advantages of Nitrofurantoin for S. saprophyticus UTIs
Maintained effectiveness: Unlike trimethoprim-sulfamethoxazole and fluoroquinolones, which have seen increasing resistance rates, nitrofurantoin has retained good activity against S. saprophyticus 2, 3
Lower resistance development: The limited systemic distribution and multiple mechanisms of action of nitrofurantoin contribute to lower rates of resistance development 4
Broad-spectrum activity: Effective against both gram-positive (including S. saprophyticus) and gram-negative uropathogens 4
Important Contraindications and Limitations
Nitrofurantoin should not be used in:
- Patients with renal impairment (CrCl <60 mL/min)
- Pregnancy at term (38-42 weeks)
- Patients with G6PD deficiency
- Patients with a history of pulmonary reactions to nitrofurantoin 1
Additionally, nitrofurantoin is not appropriate for:
Adverse Effects to Monitor
- Common: Mild gastrointestinal disturbances, skin rash
- Rare but serious: Pulmonary reactions (0.001%), hepatic toxicity (0.0003%) 1
Clinical Pearls
Nitrofurantoin should be taken with food to improve absorption and reduce gastrointestinal side effects
While some guidelines suggest limiting nitrofurantoin use in men due to concerns about prostate involvement, recent evidence suggests it may be a valuable option for uncomplicated UTIs in men without systemic symptoms 5
The Centers for Disease Control and Prevention advises avoiding fluoroquinolones for uncomplicated UTIs due to increasing resistance and risk of serious adverse effects, making nitrofurantoin an increasingly important treatment option 1
For recurrent UTIs, nitrofurantoin can also be considered for prophylaxis when non-antimicrobial interventions have failed 1
In summary, nitrofurantoin (Macrobid) is an effective antibiotic against S. saprophyticus and remains a recommended first-line treatment for uncomplicated UTIs where this pathogen is commonly encountered.