A class of antibiotics commonly used by people with cystic fibrosis (CF) was found to significantly increase the risk of permanent hearing loss in these patients when given at high dosages over time.

The study, titled “The cumulative effects of intravenous antibiotic treatments on hearing in patients with cystic fibrosis,” was published in the Journal of Cystic Fibrosis.

CF is a genetic disorder that can lead to serious, even life-threatening, infections. Patients with CF are usually prescribed antibiotics such as aminoglycosides (AG) (e.g., tobramycin or amikacin) and glycopeptide (e.g., vancomycin) to manage lung infections caused by Pseudomonas aeruginosa. These medications, while effective, can degrade auditory function in the inner ear — most often resulting in permanent loss of high-frequency sensorineural hearing.

Angela Garinis, PhD, and colleagues examined the effects of cumulative doses of intravenous AG (amikacin and/or tobramycin) and/or glycopeptide (vancomycin) on hearing, using the clinical records of 81 CF patients ages 15 to 63. (Garinis is a senior research associate with the Oregon Hearing Research Center at Oregon Health & Science University (OHSU) and a research audiologist at the VA Portland Health Care System.)

They divided the patients into two groups based on their hearing capacity (normal or evidence of hearing loss), then further grouped according to their cumulative dosage of aminoglycoside antibiotics administered intravenously.

The team, after adjusting for gender and age, found that patients exposed to the highest doses were almost five times (4.79 times) more likely to have permanent sensorineural hearing loss than those given lower doses.

Results suggest it is critical for doctors to regularly monitor hearing in CF patients who are being treated with aminoglycosides intravenously. The researchers also suggest that doctors should find alternatives for treating the symptoms of respiratory infections associated with CF, especially if patients are responsive to different classes of antibiotics.

New classes of drugs have shown a reduced toxic effect on both the kidneys and ears of CF patients, while still being able to effectively treat infections, the researchers said.

“Preventing or ameliorating the effects of permanent [hearing loss] is crucial for patients with CF who already have a significantly compromised quality of life due to the disease,” the authors wrote, according to a news release. “This information will allow both the patient and the physician to discuss possible modifications to the treatment regimen, particularly if an alternative approach is or becomes available.”

Peter Steyger, PhD, added: “People don’t realize the trauma of hearing loss until after they’ve lost it … Helen Keller said, ‘Blindness separates people from things; deafness separates people from people.’ It can lead to isolation, depression and cognitive decline.”

Steyger, a professor with the OHSU School of Medicine, lost his hearing after being treated with antibiotics for a case of meningitis at 14 months old.