A client comes to the emergency department complaining of sudden onset of diarrhea, anorexia, malaise, cough, headache, and recurrent chills. Based on the client's history and physical findings, the physician suspects Legionnaires' disease. While awaiting diagnostic test results, the client is admitted to the facility and started on antibiotic therapy. What is the drug of choice for treating Legionnaires' disease?

a) Erythromycin (Erythrocin)
b) Rifampin (Rifadin)
c) Amantadine (Symmetrel)
d) Amphotericin B (Fungizone)

Answer: a) Erythromycin (Erythrocin)