Professional and Linguistic Assessments Board (PLAB) Practice Exam

What is the recommended treatment for cellulitis in patients who are allergic to penicillin?

1. Erythromycin

2. Doxycycline

3. Vancomycin

4. Azithromycin

The correct answer is: Erythromycin

When treating cellulitis in patients with a penicillin allergy, erythromycin is often recommended due to its effectiveness against the common pathogens that cause this skin infection, particularly Streptococcus and Staphylococcus species. Erythromycin is a macrolide antibiotic that can be a suitable alternative for those who cannot tolerate beta-lactam antibiotics like penicillin. While doxycycline and azithromycin can also be effective treatments, they are not as commonly used as first-line options specifically for cellulitis in this demographic. Doxycycline is more typically reserved for certain infections, including skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and atypical infections. Azithromycin, while an effective macrolide, may not provide the broad coverage necessary for typical cellulitis pathogens compared to erythromycin. Vancomycin is usually reserved for more severe cases or when there is a known or high suspicion of MRSA involvement. It is generally not the first choice for uncomplicated cellulitis in those with a penicillin allergy, particularly in outpatient settings, because of its intravenous administration requirements and potential side effects. Thus, erythromycin emerges as the most suitable option for treating cellulitis in patients allergic to penicillin based on its