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
[{'content': 'Corynebacterium diphtheriae is \nSelect and explain. \nA. Gram positive, B. Resistant to penicillin, C. Gram negative, D. Resistant to chloramphenicol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Corynebacterium diphtheriae is a gram-positive bacillus that is unencapsulated, nonmotile, and nonsporulating. The bacteria have a characteristic club-shaped bacillary appearance and typically form clusters of parallel rays, or palisades, that are referred to as "Chinese characters."Recommended treatment options for patients with respiratory diphtheria are as follows:* Procaine penicillin G, 600,000 U IM q12h (for children: 12,500-25,000 U/kg IM q12h) until the patient can swallow comfoably; then oral penicillin V, 125-250 mg qid to complete a 14-day course* Erythromycin, 500 mg IV q6h (for children: 40-50 mg/kg per day IV in two or four divided doses) until the patient can swallow comfoably; then 500 mg PO qid to complete a 14-day courseRef: Harrison&;s Principles of Internal Medicine; 19th edition; Chapter 175; Diphtheria and Other Corynebacterial Infections', 'role': 'assistant'}]