American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the preferred regimen for patients with symptomatic cystitis who are allergic to sulfa drugs?

1. Amoxicillin for 7 days

2. Ciprofloxacin for 3 days

3. Nitrofurantoin for 5 days

4. Trimethoprim for 5 days

The correct answer is: Nitrofurantoin for 5 days

For patients presenting with symptomatic cystitis who have a sulfa allergy, nitrofurantoin is often considered the preferred regimen. Nitrofurantoin specifically targets the common pathogens that cause uncomplicated urinary tract infections, including E. coli, which is frequently responsible for cystitis. This medication is effective and typically well-tolerated. It is important to note that nitrofurantoin is usually prescribed for a shorter duration, such as 5 days in this case, which helps to minimize the risk of side effects while ensuring effective treatment. While other options like amoxicillin, ciprofloxacin, and trimethoprim are also used for treating urinary tract infections, they may not be the best choice in this scenario. Amoxicillin could be less effective against resistant strains of E. coli, especially in regions where resistance is common. Ciprofloxacin, a fluoroquinolone, is effective but is usually reserved for situations where a first-line agent cannot be used. Trimethoprim also carries the risk of cross-sensitivity in patients with sulfa allergies, as it is often combined with sulfamethoxazole in common formulations. Thus, nitrofurantoin stands out as a safer and effective option for this patient group