This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': 'Clindamycin is the drug of choice in - \nSelect and explain. \nA. Methicillin resistance Staph. Aureus, B. Mycoplasma pneumoniae, C. Bacteroidis fragilis, D. Pseudomonus infection', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In general, B. fragilis is susceptible to metronidazole, carbapenems, tigecycline, beta-lactam/beta-lactamase inhibitor combinations (e.g., Unasyn, Zosyn), and ceain antimicrobials of the cephalosporin class, including cefoxitin. The bacteria have inherent high-level resistance to penicillin. Production of beta lactamase appears to be the main mechanism of antibiotic resistance in B. fragilis. Clindamycin is no longer recommended as the first-line agent for B. fragilis due to emerging high-level resistance (>30% in some repos) Ref Harrison20th edition pg 1079', 'role': 'assistant'}]