Aminoglycoside induced ototoxicity in patients with cystic fibrosis

The improved survival of cystic fibrosis (CF) patients is partly due to intensive treatment for their chronic infections. Treatment usually includes intravenous and nebulised aminoglycoside antibiotics and they receive a large cumulative dose of these antibiotics over their lifetime. There is little information in the literature on the prevalence of ototoxicity due to aminoglycoside in these patients. We performed pure tone audiometry on 43 CF patients aged 14-42 years. Seven (16%) had bilateral sensorineural hearing loss (SNHL) for high frequency sounds, consistent with aminoglycoside induced ototoxicity. However, only 2 of these patients had documented toxic serum levels in the past. The identification of bilateral SNHL in one in six adult CF patients is a cause for concern. It may be that the high cumulative dose of aminoglycosides received by these patients may be causing inner ear injury in the absence of specific episodes of toxic serum levels.