A widely used family of antibiotics called Aminoglycoside has been linked to hearing loss, and children are at the highest risk. The drugs are used to combat respiratory diseases and meningitis in those with cystic fibrosis as well as babies born prematurely in neonatal intensive care. This family of antibiotics includes gentamycin, tobramycin, and kanamycin and streptomycin. Worryingly, an estimated 20-60 percent of all patients who receive aminoglycoside antibiotics develop partial or complete hearing loss.
Researchers at the Oregon Health and Science University School of Medicine conducted the study. They ran an experiment involving two groups of mice that were given a small dose of aminoglycoside. Before the test, the first group was healthy and the second group had an inflammation infection and the results showed the former group experienced only a minor case of hearing loss, and the latter group suffered much more severe hearing damage. They concluded that aminoglycoside antibiotics were more dangerous for patients with inflammatory bacterial infections.
When patients develop a bacterial infection, it creates an inflammation in many parts of the body including the inner ear. The aminoglycoside antibiotic used to combat this looks to destroy the infection wherever it resides. And when the cochlea and auditory nerve are also inflamed, their sensory cells also become damaged as the antibiotics do their job. They become even more dangerous for hearing when they are used in conjunction with other medicines like diuretics.
And these drugs are common. According to the American-Speech-Language-Hearing Association, there are more than 200 known ototoxic medications on the market today, though they are only reserved for life-threatening infections.
Children seem to be the most at risk of this type of ototoxic medicine as they are often administered to combat complications at birth. A study in England found 20,000 premature babies were given the antibiotics each year, and one in 500 of those children were found to have a genetic mutation making them susceptible to aminoglycosides.
Hearing loss has serious ramifications for infants. Unable to speak yet, it can obstruct their language and social development which in turn affects their employability and future life chances.
In the end though, as babies are unable to report their symptoms, we will never know exactly how many premature babies suffer hearing loss as a side effect of treatment with the drug.
If all of this sounds frightening, it will reassure you to know that the problem is well known in the scientific community, the members of whom are already taking steps to reduce our reliance on the drug. In a study published in Journal of Clinical Investigation, scientists at the Stanford University School of Medicine have created an improved type of aminoglycoside called N1MS, which has been tested on mice with no reports of hearing damage. It works by blocking the drug from making contact with the sensory hair cells, avoiding any damage. But it could be a few years before this drug will become available.
In the meantime, researchers from The Institute of Child Health in London, England have pushed for patients to be screened for vulnerabilities to aminoglycosides before being administered them. Costing an average of $70, the researchers claim they would save more money by preventing a significant cause of non-genetic hearing loss, which would ease the strain on government subsidized healthcare plans. Indeed, studies estimate that a child who has hearing loss before language acquisition costs society a total of one million dollars!
If you have questions about hearing loss, feel free to contact us at Hearing at Home!