This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Drug of choice for Listeria monocytogenes is 
Select and explain. 
A. Amoxycillin, B. Ampicillin, C. Vancomycin, D. Amikacin
B: Ampicillin
Answer: B: Ampicillin 
Explanation: Non-Spore-Forming Gram-Positive Bacilli: Corynebacterium, Propionibacterium, Listeria, Erysipelothrix, Actinomycetes, & Related Pathogens
Many antimicrobial drugs inhibit listeria in vitro. Clinical cures have been obtained with Ampicillin with erythromycin, or with intravenous trimethoprim-sulfamethoxazole.
Cephalosporins and fluoroquinolones are not active against L monocytogenes. Ampicillin plus gentamicin is often recommended for therapy, but gentamicin does not enter host cells and may not help treat the listeria infection