New research on mice suggests that a specific class of life-saving antibiotics puts patients at a greater risk for hearing loss than previously thought. The study, published online July 29 in the journal Science Translational Medicine, suggests that drugs classified as aminoglycoside antibiotics pose the most risk to patients with inflammatory bacterial infections.
Aminoglycoside antibiotics are used to treat meningitis, bacteremia, and respiratory diseases in patients with cystic fibrosis. Although they are an important part of physicians’ life-saving arsenal, the drugs are known to damage the sensory cells in the inner ear that detect sound and motion.
The study authors explained that the inflammation that accompanies bacterial infections boosts the uptake of aminoglycosides into the inner ear, substantially increasing the risk of hearing loss. Infants in neonatal intensive care units (NICUs) are at particular risk.
According to an Oregon Health & Science University news release, approximately 80 percent of the 600,000 infants admitted to NICUs in the U.S. receive aminoglycoside antibiotics. Between 2 percent and 4 percent of premature babies in NICUs suffer a hearing loss. That compares with 0.1 percent to 0.3 percent of full-term infants who had a hearing loss from congenital causes.
“Currently, it’s accepted that the price some patients have to pay for surviving a life-threatening bacterial infection is the loss of their ability to hear,” lead author Peter S. Steyger, PhD, professor of otolaryngology, head and neck surgery at the Oregon Hearing Research Center, Oregon Health & Science University School of Medicine, said in the news release.
And he should know. As a toddler in the U.K., Steger’s case of meningitis was treated with streptomycin, an aminoglycoside, and he lost his hearing.
“I’ve been fortunate,” Steyger told The Oregonian. “I learned to listen and speak as a young child.” The recipient of a cochlear implant a decade ago, he still requires a hearing aid.
For the study, Steyger and his colleagues gave healthy mice a low amount of aminoglycoside antibiotics and found they experienced a small degree of hearing loss. However, when mice that had inflammation that is typical of infections treated with aminoglycosides were given the same dose, the degree of hearing loss was significantly greater.
“If you give a healthy animal, or a healthy human, an aminoglycoside for long enough they will go deaf, Steyger explained in The Oregonian. “If they have an infection that induces an inflammation response, they will lose their hearing much faster.”
The study authors hope their research will lay the groundwork for improving standard of care guidelines for patients receiving aminoglycoside antibiotics. To protect patients’ hearing, Steyger and his team called for the development of more targeted aminoglycosides and urged clinicians to choose more targeted antibiotics that did not harm hearing to treat severe infections.
“We must swiftly bring to clinics everywhere effective alternatives for treating life-threatening infections that do not sacrifice patients’ ability to hear,” Steyger said.