American Board of Internal Medicine (ABIM) Certification Practice Exam

What alternative antibiotic regimen could be considered for patients allergic to β-lactam antibiotics after a dog bite?

1. Doxycycline alone

2. Trimethoprim-sulfamethoxazole plus clindamycin

3. Only ciprofloxacin

4. Vancomycin

The correct answer is: Trimethoprim-sulfamethoxazole plus clindamycin

In the case of dog bites, it is essential to provide effective antibiotic therapy to prevent or treat infections, particularly from common pathogens associated with animal bites, such as Pasteurella multocida and Staphylococcus aureus. For patients with a history of allergy to β-lactam antibiotics, an alternative treatment regimen is necessary to ensure both efficacy against these pathogens and safety for the patient. The combination of trimethoprim-sulfamethoxazole and clindamycin is a suitable alternative. Trimethoprim-sulfamethoxazole provides coverage against a variety of gram-positive and some gram-negative bacteria, making it effective against potential pathogens from dog bites. Clindamycin adds further coverage, particularly for anaerobic bacteria and resistant Staphylococcus species. This combination effectively targets the pathogens involved in infections following animal bites while avoiding β-lactam antibiotics, which the patient is allergic to. Doxycycline alone, while it does have some efficacy against common pathogens, may not provide the comprehensive coverage needed for dog bites, particularly for the anaerobic bacteria involved. Ciprofloxacin may not cover all the relevant pathogens and is typically not the first-line choice for dog bites. Vancomycin is primarily used for severe infections caused by