Indications: urinary-tract infections, otitis media, sinusitis, oral infections, bronchitis, uncomplicated community-acquired pneumonia (Haemophilus influenzae infections, invasive salmonellosis; listerial meningitis.

Cautions: history of allergy; renal impairment; erythematous rashes common in glandular fever, cytomegalovirus infection, and acute or chronic lymphocytic leukaemia.

Contra-indications: penicillin hypersensitivity.

Side Effects: nausea; diarrhoea; rashes; rarely, antibiotic- associated colitis.

Dose: By intramuscular injection or intravenous injection or infusion, 500 mg every 4–6 hours; CHILD under 10 years, half adult dose.

Endocarditis (in combination with another antibiotic if necessary), by intravenous infusion, 2 g every 6 hours, increased to 2 g every 4 hours e.g. in enterococcal endocarditis or if ampicillin used alone.

Listerial meningitis (in combination with another antibiotic), by intravenous infusion, 2 g every 4 hours for 10–14 days; NEONATE 50 mg/kg every 6 hours; INFANT 1–3 months, 50–100 mg/kg every 6 hours; CHILD 3 months–12 years, 100 mg/kg every 6 hours (max. 12 g daily).