Treatment of ampicillin-resistant Haemophilus influenzae in soft tissue infections with high doses of ampicillin.

Six soft tissue infections (three epiglottitis, one cellulitis, one pneumonia, and one arthritis) with ampicillin-resistant Haemophilus influenzae were treated initially with high doses of ampicillin (200 to 400 mg/kg/day intravenously) alone and had good clinical responses. All had documented bacteremia with H. influenzae. One child was treated only with ampicillin; treatment in the remainder was changed to oral therapy with other antibiotics to facilitate discharge. There was no recurrence of disease. Disc diffusion studies done on clinical isolates of both resistant and sensitive organisms indicate a break point at which the resistant organism shows progressive sensitivity to increasingly higher concentrations of ampicillin.