COMBINED ACTION OF CHLORAMPHENICOL AND AMPICILLIN ON HEMOPHILUS-INFLUENZAE

Combined therapy with chioramphenicol and ampicillin may be used for the treatment of Haemophilus Influenzae meningitis. This study was undertaken to determine whether there was antagonism between these two drugs used in combination. Kinetic killing experiments showed that no apparent antagonism occurred at high concentrations of chloramphenicol (5 to 10 mg/l), but that low concentrations of chloraniphenicol (1 to 2 mg/l) were antagonistic to the bactericidal activity of ampicillin. It is possible that failure of combined therapy may be attributed to such interactions. © 1979, by The British Society for Antimicrobial Chemotherapy.