Which of the following is the most effective agent in the treatment of Rickettsia infections?
a. Tetracycline is one of the drugs of choice in the treatment of Rickettsia, Mycoplasma, and Chlamydia infections
b. The antibiotics that act by inhibiting cell-wall synthesis have no effect on Mycoplasma because the organism does not possess a cell wall; penicillin G, vancomycin, and bacitracin will be ineffective.
c. Gentamicin has little or no antimicrobial activity with these organisms.