Professional and Linguistic Assessments Board (PLAB) Practice Exam

What is the first-line treatment for Legionella pneumonia?

1. Erythromycin

2. Doxycycline

3. Piperacillin

4. Amoxicillin

The correct answer is: Erythromycin

The first-line treatment for Legionella pneumonia is commonly with a macrolide or a fluoroquinolone, with erythromycin being one of the historically favored options. Legionella pneumophila, the bacterium responsible for this type of pneumonia, requires antibiotics that penetrate cell membranes effectively, due to its intracellular nature. Erythromycin is significant in managing this condition, particularly in patients who may have milder manifestations of pneumonia or those who are treated on an outpatient basis. While doxycycline can also be effective against Legionella, it is not as widely considered the primary treatment option as erythromycin for severe cases. Additionally, piperacillin and amoxicillin are generally not effective against Legionella, as they target a different spectrum of bacteria—specifically, they are beta-lactam antibiotics whose spectrum does not adequately cover atypical pathogens like Legionella. In summary, the use of erythromycin as the first-line treatment aligns with clinical guidelines and historical practice, making it the correct choice in the management of Legionella pneumonia.