Antibiotics can in some situations cause hearing loss. The results of the tests with mice, which indicate the opposite, are therefore very surprising. The study has been carried out at the Washington University School of Medicine.
Babies have the most sensitive ears
Babies get gentamicin - an antibiotic - because it can protect them against a wide range of infectious bacteria, and it is the mildest antibiotic in its class. But it is also a drug that can cause hearing loss in people, especially in combination with noise. Babies are especially vulnerable to hearing damage. The studies with mice now show that, paradoxically, kanamycin (a close relation to gentamicin) protects the ears when given in extended low doses in very young mice.
Because the first month of life is when mice, like babies, are most vulnerable to noise and drugs that damage hearing, 20- to 30-day old mice were injected with kanamycin twice a day for 11 days. They were then exposed to 110 decibels of noise for 30 seconds. Surprisingly a regular, low dose of kanamycin completely protected the mice against sensory cell damage and hearing loss. The protective effect of repeated doses persists for at least two days after the last injection, the scientists noted.
These results now lead to new research. Learning how kanamycin protects the sensory cells of the ear could help scientists develop drugs with similar effects. Medications that protect the ears from damaging noise levels could benefit a wide range of groups, from soldiers to airline workers to premature babies.
Mice the perfect test subject
Mice are a well-established model for human hearing, as they possess similar inner ear anatomy and physiology and similar patterns of age-related, noise-induced and drug-related hearing loss as humans.
Research started after a lucky break
The research, which has led to the discovery of the beneficial antibiotics, actually started in a completely different place. A nurse, who worked with helicopter transport, was worried about small children being subjected to the loud noises that come with helicopters. She therefore contacted Professor William Clark at Washington University School of Medicine, who then started the study.