Over the decades, medicine has provided miraculous treatments for some of the most serious diseases and infections. Considered a significant medical achievement of the 20th century, antibiotics have eased pain and suffering – and saved lives. When survival is the ultimate goal, there is a class of antibiotics used to strengthen resistance to unyielding bacterial infections. But did you know they can also significantly weaken your hearing?
These “Aminoglycosides” are known as bactericidal antibiotics as they kill bacteria directly and prevent the further production of the proteins needed to survive. Typically administered for severe infections, they are usually given intravenously in a clinical setting, although some can be taken orally and as drops for the eyes and ears. Some examples of aminoglycosides – and their approved indications are:
- Gentamicin – Administered by IV for meningitis, pneumonia, E. coli, Staphylococcus infections, listeria, respiratory tract infections, urinary tract infections, diverticulitis, bone infections, cystic fibrosis, and more. Given orally for peritonitis, topically for burns and skin infections, by ophthalmic drops for eye infections, and by injection for Meniere’s disease.
- Streptomycin – Given by IV for tuberculosis, brucellosis, tularemia, pneumonic septicemic, and bubonic plagues.
- Amikacin – Administered by IV for highly drug-resistant organisms, as well as meningitis and uncomplicated urinary tract infections.
- Neomycin – Topical treatment for skin infections from minor wounds and taken orally for hepatic encephalopathy (a syndrome of liver dysfunction) or hypercholesterolemia (high cholesterol).
- Tobramycin – Administered through IV for lower respiratory infections, osteomyelitis (bone infections), urinary tract or abdominal infections, meningitis and skin infections, and by nebulizer for infections in cystic fibrosis.
- Kanamycin – Given through IV for tuberculosis and gonorrhea and orally for necrotizing enterocolitis (intestinal disease) in the fetus or newborns.
You may not be familiar with the therapies listed above. However, they are a critical line of defense for illnesses that remain life-threatening to young and old. In as much as they are powerful, their side effects can be equally matched. It is important to be aware of the major irreversible toxicity of aminoglycosides – ototoxicity (toxic effect on the ears) – that can impact in one of two ways. Vestibulotoxic damage (from streptomycin and gentamicin) can cause dizziness and ataxia (slurred speech, stumbling), and auditory or cochleotoxic damage (from amikacin, neomycin, and kanamycin) that can produce permanent hearing loss.
Research reveals possible causes of hearing loss from antibiotics
For years, scientists have been uncertain as to why these antibiotics can lead to hearing loss. One study reveals the reason for hearing loss is most likely inflammation. While that may not seem groundbreaking, it potentially is. Because if your doctor determines these antibiotics are crucial to your recovery, they can also take measures to make sure that you don’t suffer from inflammation at the same time, thereby limiting your risk for hearing loss.
In addition, there are details that can help you recognize an adverse reaction when sensory cells within the inner ear become damaged. An early warning sign of ototoxicity is tinnitus (ringing in the ears) followed by hearing loss. The ability to understand speech can be affected as well as your sense of balance. Ototoxicity may be initially overlooked as it can start when a round of treatment has ended, with the onset of symptoms developing slowly thereafter.
Despite their undesirable effects, these broad-spectrum antibiotics remain vital for their potency and efficacy. They are hypoallergenic – especially important in an emergency situation and indispensable for certain diseases such as tuberculosis and bacteria in patients with cystic fibrosis. Factor in the fight against the rise of multi-drug resistant bacteria, as well as the low cost of production, and you have a solution for infections that are getting harder to fight and for vulnerable and economically disadvantaged populations.
More research is needed to develop ways of protecting patients from ototoxicity. There is currently no approved protective strategy or reversible option, though the insights on inflammation should be taken into consideration. Aminoglycosides may also generate free radicals within the inner ear that destroy healthy sensory cells and neurons, resulting in permanent hearing loss. Currently, researchers are testing the power of antioxidant vitamins in human clinical trials to learn if they can somehow prevent hearing damage by eliminating free radicals, thereby protecting against their effects. It is recommended by specialists to monitor your hearing and balance systems prior to and during treatment. Establishing a baseline with an audiologist can provide information that will help you and your doctor make decisions about whether to stop or change drug therapy before your hearing can be impaired.