Ampicillin Treatment Guidelines for Bacterial Infections

Adult Dosing Guidelines

For uncomplicated urinary tract infections, the American Heart Association recommends ampicillin 18-30 g/day IV in divided doses 1
For infective endocarditis, the American Heart Association recommends ampicillin 200-300 mg/kg/day IV divided every 4-6 hours up to 12 g daily 2, 3
For HACEK group infections, the American Heart Association recommends ampicillin 200-300 mg/kg/day IV divided every 4-6 hours up to 12 g daily 3

For neonates and infants with gestational age >34 weeks and postnatal age ≤7 days, the Journal of Microbiology, Immunology and Infection recommends ampicillin 50 mg/kg/dose IV every 12 hours 1
For neonates and infants with gestational age >34 weeks and postnatal age >7 days, the Journal of Microbiology, Immunology and Infection recommends ampicillin 75 mg/kg/dose IV every 12 hours 1

For uncomplicated urinary tract infections, the Journal of Microbiology, Immunology and Infection recommends treatment for 3-7 days 1, 4
For infective endocarditis, the American Heart Association recommends treatment for generally 4-6 weeks 3

For vancomycin-resistant enterococci (VRE) in uncomplicated UTIs, the Journal of Microbiology, Immunology and Infection recommends ampicillin 18-30 g/day IV in divided doses or amoxicillin 500 mg PO/IV every 8 hours 1, 4
For HACEK group infections, the American Heart Association recommends ampicillin 200-300 mg/kg/day IV divided every 4-6 hours (up to 12 g daily) plus aminoglycoside 3
When treating endocarditis caused by enterococci, the American Heart Association recommends combination therapy with gentamicin for the first 2 weeks 6
For HACEK microorganisms, the American Heart Association recommends ceftriaxone as the preferred treatment due to increasing β-lactamase production, and ampicillin should not be used without susceptibility testing 5