<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 70-year-old man presents with fever, headache, and vomiting. He says that symptoms onset acutely 2 days ago and have not improved. He also reports associated weakness and chills. Past medical history is significant for occasional heartburn. His temperature is 39.4C 103.0F, the pulse rate is 124min, the blood pressure is 13084 mm Hg, and the respiratory rate is 22min. On physical examination, there is significant nuchal rigidity. No signs of raised intracranial pressure are present. A lumbar puncture is performed and cerebrospinal fluid CSF analysis shows lymphocyte-dominant pleocytosis with increased CSF protein levels. Bacteriological culture of the CSF reveals the growth of Listeria monocytogenes. Which of the following antibiotics is the best choice for the treatment of this patient?? A: Ampicillin, B: Ceftriaxone, C: Chloramphenicol, D: Ciprofloxacin, E: Vancomycin,  <response>: This is a clinical vignette describing a 70-year-old man with acute onset fever, headache, vomiting, weakness, and chills. He has neck stiffness on exam and CSF analysis shows lymphocytic pleocytosis with increased protein and growth of Listeria monocytogenes on culture. This presentation is most consistent with listerial meningitis. The antibiotic choices provided cover different spectrums of activity. Ampicillin has excellent activity against Listeria monocytogenes and is considered first-line therapy. Ceftriaxone has poor activity against Listeria. Chloramphenicol has activity but is not preferred due to side effects. Ciprofloxacin and vancomycin have little to no activity against Listeria. Therefore, ampicillin is the best choice.A: Ampicillin 