The following antibiotics are used to treat Shigella dysentery: Beta-lactams: Ampicillin, amoxicillin, third-generation cephalosporins (cefixime, ceftriaxone), and pivmecillinam (not available in the United States) Quinolones: Nalidixic acid, ciprofloxacin, norfloxacin, and ofloxacin. Macrolides: Azithromycin.