American Board of Internal Medicine (ABIM) Certification Practice Exam

Which bacteria is treated with azithromycin or erythromycin?

1. Yersinia

2. Campylobacter

3. Salmonella

4. Vibrio

The correct answer is: Campylobacter

Azithromycin and erythromycin are macrolide antibiotics that are particularly effective against a variety of bacterial infections, notably those caused by Campylobacter species. Campylobacter is a leading cause of bacterial gastroenteritis, and while the primary treatment for mild cases may simply be supportive care, more severe infections or cases in patients with specific risk factors often warrant antibiotic therapy. Macrolides like azithromycin are preferred due to their excellent gastrointestinal absorption and efficacy against Campylobacter jejuni. This effectiveness is especially important in certain populations, such as immunocompromised individuals, where a swift and effective treatment is critical to avoid complications. In contrast, other listed bacteria such as Yersinia, Salmonella, and Vibrio may be treated with different classes of antibiotics based on susceptibility patterns and the severity or type of infection. For example, Yersinia infections might be managed with tetracyclines or aminoglycosides, while Salmonella often resolves without antibiotics, and Vibrio infections can frequently be treated with doxycycline. This highlights the specific role of azithromycin and erythromycin in treating Campylobacter, making it the correct choice for this question.