This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Which of the following most accurately describes the therapy available for the prevention and treatment of C. diphtheriae 
Select and explain. 
A. Antimicrobial therapy for prophylaxis only, B. Diphtheria toxoid (DPT) booster vaccination only, C. Antitoxin only, D. Antimicrobial therapy and prophylaxis, antitoxin, and toxoid (DPT)
D: Antimicrobial therapy and prophylaxis, antitoxin, and toxoid (DPT)
Answer: D: Antimicrobial therapy and prophylaxis, antitoxin, and toxoid (DPT) 
Explanation: Protection against C. diphtheriae can be established through both active and passive immunity. Active immunity consists of a toxoid administered in the form of the DPT vaccine. Passive immunity is established by administering diphtheria antitoxin (immunoglobulins). Antimicrobial therapy (erythromycin) can be used to effectively treat patients with clinical diphtheria.