PORTLAND, OR—As a 14-month-old baby in England, Peter Steyger suddenly lost his hearing, the result of an antibiotic given to him to treat meningitis. Now, 48 years later, as a scientist at the Oregon Hearing Research Center at Oregon Health & Science University (OHSU), he may have discovered exactly how aminoglycosides, the class of antibiotics that caused his deafness.
In a study published last month in Scientific Reports, Steyger and his OHSU colleague Hongzhe Li offer an explanation of how aminoglycoside antibiotics are able to kill the hair cells in the inner ear that enable people to hear. Normally, they explain, a “blood-labyrinth” barrier prevents potentially damaging components in the blood from entering the inner ear. However, Steyger and Li’s research indicates that these antibiotics foil the barrier and reach the inner ear via pathways that are designed to admit minerals and nutrients needed for auditory function.
If the authors are correct about how these ototoxic medications are able to kill hair cells, then scientists can try to identify the mechanism that allows them to cross the blood-labyrinth barrier and find a way to prevent this from occurring. For example, said Steyger in an interview for the online publication Science Newsline Medicine, “We could give an inhibitor at the same time as the antibiotics that will protect the ear, but still allow the drug to kill bacteria, thereby saving the patient’s hearing.”
Steyger and his lab have already begun researching the precise molecular mechanisms by which aminoglycoside antibiotics (and other ototoxic drugs) cross the blood-labyrinth barrier. They hope what they learn will lead to the development of effective strategies to prevent drug-induced hearing loss.
If an effective blocker is found that enables aminoglycoside antibiotics to be used safely, Steyger estimates that it would save the hearing of up to 50,000 people a year in the United States alone, most of them prematurely born infants. He noted that about 80% of these newborns are given aminoglycoside antibiotics to prevent infections that would otherwise kill them.
In addition, the same type of antibiotics is also used to treat people with tuberculosis, mostly in developing countries.
Steyger, who holds a PhD in hearing research from Keele University in the UK, is an associate professor of otolaryngology/head and neck surgery at the Oregon Hearing Research Center. His study was funded by the National Institute of Deafness and Other Communications Disorders.