When he was a child, Dr. Peter Steyger, professor of otolaryngology at the Oregon Health & Science University School of Medicine, was treated for meningitis with an aminoglycoside antibiotic that subsequently lead to the loss of his hearing.
Aminoglycoside antibiotics are a strong and effective treatment for inflammatory bacterial infections such as meningitis, bacteremia, and respiratory diseases in patients with cystic fibrosis. However, the side effect of this drug is detrimental to inner ear sensory cells that detect sound and motion.
In their study, Dr. Steyger and his colleagues at the Oregon Hearing Research Center tested the effects of aminoglycoside antibiotics on mice, both healthy and with inflammatory bacterial infections. They found that healthy mice given a small dose of aminoglycoside antibiotics experienced a low level of hearing loss. At the same time, mice with inflammation experienced a higher degree of hearing loss.
For lethal infections, the use of aminoglycoside antibiotics is often necessary to save a life, even at the expense of hearing loss. Their cost-effectiveness and availability make them a popular treatment around the world, though there are newer, better options. Additionally, their lack of need for refrigeration makes them convenient in warmer parts of the globe. However, this drug has been linked to kidney poisoning, as well as hearing loss. Aminoglycoside antibiotics pose a greater risk to infants in infant intensive care units the US, where 80% of infants are given aminoglycosides.
“When infants lose their hearing,” says Dr. Steyger, “they begin a long and arduous process of developing the skill of speaking and listening. This can interfere with their educational and psychosocial development, all of which can have a dramatic impact on their future employability, income, and quality of life.” He urges that medical professionals utilize more targeted aminoglycosides, as well as other non-toxic antibiotics when possible. He and his team also call for further research and development on an effective antibiotic that does not damage hearing.
The good news: Stanford University researchers have developed a targeted aminoglycoside antibiotic that spares damage to inner ear sensory cells and kidney damage. Dr. Anthony Ricci and Dr. Alan Cheng combined their specializations of otolaryngology and clinical science to solve this problem: they formulated a way to block aminoglycosides from attacking non-generating hair cells in the ear. Many researchers, through the years, have attempted a solution to this problem. It was difficult to separate the elements of aminoglycoside that were effective and destructive.
Says Dr. Ricci, “We figured, well, let’s not mess with that part of the drug [which fights off infection]. We targeted sites on the drug molecule that were not involved in the antimicrobial activity that kills off infection. This allowed us to reduce toxicity to the ear while retaining antimicrobial action.”
Though it took Drs. Ricci and Cheng four years to develop a small amount of this newly-tailored antibiotic, they are optimistic about its efficacy. This new drug, N1MS, derived from sisomicin, a type of aminoglycoside, is newly patented. “If we can eventually prevent people from going deaf from taking these antibiotics, in my mind, we will have been successful,” says Dr. Ricci.
Are you or a loved one experiencing hearing loss? At Desert Valley Audiology, we offer comprehensive audiological services at our conveniently located practices in Las Vegas, Tenaya and Henderson. Contact us today to schedule a consultation with one of our audiologists.