Many patients receive aminoglycoside antibiotics to treat infections. In this lesson, learn the names of the different aminoglycoside antibiotics and some of the problems a patient may experience when taking one of these antibiotics.
What Is an Aminoglycoside?
An aminoglycoside is a type of very powerful antibiotic used to treat serious bacterial infections.
Aminoglycosides are especially useful in treating infections caused by certain gram-negative bacteria that are responsible for infections such as meningitis, tuberculosis, and plague. The very first aminoglycoside, streptomycin, was discovered in 1944. Today there are several other aminoglycosides: amikacin, gentamicin, kanamycin, neomycin, and tobramycin.
Risks of Aminoglycosides
Receiving an aminoglycoside antibiotic can often mean the difference between life and death for some patients. But while aminoglycosides are working to kill the bad bacteria, they can also cause some serious toxic effects that can hurt the patient.To learn about side effects and potential toxicity of aminoglycosides, let’s visit Jack, a patient in the hospital who is being treated with an aminoglycoside antibiotic. Jack is in the hospital with a very bad infection.
After weighing the benefits of receiving the antibiotic against potential risks, Jack’s healthcare provider prescribes gentamicin. Gentamicin is a commonly used aminoglycoside, so as we learn about gentamicin, we’ll learn about the other aminoglycosides, too.During his treatment, Jack will be monitored very closely for side effects and toxicity caused by gentamicin. For example, Jack could experience an itchy rash, which is a common side effect that’s usually not serious. On the other hand, Jack’s kidneys and ears are very susceptible to damage from the gentamicin.Aminoglycosides tend to concentrate in the little units inside the kidneys called nephrons.
Because it can be toxic to the nephrons, the gentamicin Jack is receiving is a considered a potentially nephrotoxic antibiotic. Aminoglycosides also tend to concentrate inside the nerve responsible for hearing and balance;the eighth cranial nerve. Because aminoglycosides can damage this nerve, the gentamicin Jack is receiving is considered a potentially ototoxic antibiotic.
Effects of Toxicity
Our kidneys are important in maintaining fluid and chemical balance, so we can tell if Jack’s kidneys are being damaged if we see any changes in Jack’s urine or blood. Some things we’ll look at include:
- How much urine is Jack making? Is urine output different when compared with the amount of fluid he’s taking in?
- What color is Jack’s urine? Is it getting lighter or darker?
- What’s in the urine? Is the kidney allowing things in the urine that are not usually found in the urine?
- What’s in the blood? Are there waste products building up in the blood that are usually eliminated by the kidneys?
The function of Jack’s eighth cranial nerve will also be checked to make sure it’s working properly.
We’ll know if the nerve has suffered some damage if Jack is experiencing problems like:
- A ringing sound in the ears (referred to as tinnitus)
- Dizziness or loss of balance
- Hearing loss, especially high frequency sounds
Jack is receiving an antibiotic that is potentially nephrotoxic and ototoxic, so our goal for Jack is that the infection will be treated without him suffering any toxicity. Here are a few situations that make toxicity more likely and how it can be prevented:High gentamicin levels in Jack’s blood: High blood levels of aminoglycosides are a common cause of toxicity. To prevent this, Jack’s gentamicin levels will be measured before each dose is administered. If it’s too high, his next dose will be delayed until the level comes down.Preexisting kidney and liver problems: We’ll want to know what Jack’s baseline kidney and liver function is before the first dose is given. Most drugs, including gentamicin, are metabolized in the liver and eliminated through the kidneys, so the levels of gentamicin in Jack’s body can increase if the function of these organs isn’t ideal. His dose may need to be adjusted to prevent toxicity.
Other toxic medications: Sometimes patients need to take more than one medication with a similar potential for toxicity, so we’ll want to know what other medications Jack is taking. A substitute for his other medications may be needed in order to reduce the potential for toxicity.
Aminoglycosides are very useful antibiotics that help fight serious infections. But because they can hurt the patient as well as the bacteria, they are only used for certain serious infections. And, patients who receive aminoglycosides must be watched carefully to prevent ototoxicity (problems with hearing and balance) and nephrotoxicity (problems with kidney function).