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': 'Rickettsia is treated in all ages by which drug? \nSelect and explain. \nA. Doxycycline, B. Penicillin, C. Macrolides, D. Quinolones', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Doxycycline* The drug of choice for the treatment of both children and adults with rocky mountain spotted fever is doxycycline, except when the patient is pregnant or allergic to the drug.* Because of the severity of RMSF, immediate empirical administration of doxycycline should be strongly considered for any patient with a consistent clinical presentation in the appropriate epidemiologic setting.* Treatment with chloramphenicol, a less effective drug, is advised only for patients who are pregnant or allergic to doxycycline.* Beta-lactam antibiotics, erythromycin, and amino glycosides have no role in the treatment of RMSF, and sulfa-containing drugs are likely to exacerbate this infection. There is little clinical experience with fluoro- quinolones, clarithromycin, and azithromycin, which are not recommended.', 'role': 'assistant'}]