Hearing loss as a sequel to chloramphenicol and ampicillin treatment of Haemophilus influenzae meningitis.

20 patients with Haemophilus influenzae meningitis who had been treated with chloramphenicol over the period 1959-1970 and 23 patients who had been treated with ampicillin over the period 1968-1974 were re-examined by hearing tests in 1975. In all the cases the two agents had been given initially by the parenteral route, chloramphenicol in doses varying between 50 and 150 (averaging 101) mg/kg/day and ampicillin in doses varying between 125 and 350 (averaging 229) mg/kg/day. Five of the 20 patients in the chloramphenicol group were found to be deaf on one ear, whereas 1 of the 23 patients in the ampicillin group was completely deaf. A further 3 in the chloramphenicol group and 1 in the ampicillin group had slight sensorineural hearing loss on one ear. Only in 2 of the 6 deaf patients was the loss discovered during the time of hospital care. The present study has not provided any evidence supporting the recently reported observation (Gamstorp and Klockhoff, 1974) that the frequency of hearing loss might be higher after ampicillin than after chloramphenicol treatment for H. influenzae meningitis.