American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the first-line treatment for uncomplicated cutaneous anthrax?

1. Ciprofloxacin or doxycycline

2. Amoxicillin or cephalexin

3. Vancomycin or linezolid

4. Metronidazole or clindamycin

The correct answer is: Ciprofloxacin or doxycycline

The first-line treatment for uncomplicated cutaneous anthrax is ciprofloxacin or doxycycline. This is based on the efficacy of these antibiotics against Bacillus anthracis, the bacteria responsible for anthrax. Both ciprofloxacin, a fluoroquinolone, and doxycycline, a tetracycline, are effective due to their ability to inhibit bacterial protein synthesis and DNA replication. Ciprofloxacin is commonly used for various bacterial infections, making it a reliable choice for anthrax, particularly due to its strong performance against Gram-positive organisms and its oral bioavailability. Doxycycline serves as an effective alternative, noted for its good tissue penetration and ability to treat a range of infections, including those caused by atypical bacteria. The broad-spectrum activity of both of these antibiotics against the pathogens associated with anthrax makes them suitable options for this condition. Other treatments listed, such as amoxicillin or cephalexin, are not preferred due to their limited effectiveness against Bacillus anthracis. Similarly, vancomycin or linezolid, though effective against resistant Gram-positive bacteria, are not first-line treatments for cutaneous anthrax, as the conditions typically require more targeted therapy. Metronidazole or clindamycin are also inappropriate