In this review, I will be covering a group of antibiotics called Aminoglycosides.
The nurse should be familiar with what microorganisms this group of antibiotics target, how they work, and the nursing considerations when administering these medications.
Don’t forget to watch the lecture on Aminoglycosides and to take the quiz after reviewing this material.
Aminoglycosides (Antibiotics) Nursing Pharmacology Review
This is a particular class of antibiotic medications that are great at targeting mainly gram-negative microorganisms.
- Gram-negative microorganisms include: E. coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Serratia marcescens, Enterobacter and more.
They’re not very helpful with most gram-positive microorganisms, but can help target a few like Staphylococcus aureus or Enterococcus.
Plus, this group of antibiotics can help with mycobacteria infections too like Mycobacterium tuberculosis.
Due to the type of microorganisms Aminoglycosides can target, these antibiotics may be prescribed in cases of septicemia, severe urinary tract infections, skin/bone/ear/eye/pelvic/abdominal infections, endocarditis (infection on the heart’s valves), and pneumonia especially hospital-acquired types.
In practice, you can see Aminoglycosides prescribed with other antibiotics like Penicillin. This is because when used together they can create a working (hence synergistic) relationship with each other. For example, the synergy effect created can allow the Aminoglycoside to get into the bacteria where it wouldn’t have been able to do it all by itself.
What medications it includes?
Remember GNATS:
GN: for gram-negative
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
How they’re Administered?
Aminoglycosides are not absorbed very well orally. Therefore, they are mainly administered via the parenteral route (IM or IV) …Mainly given IV or IM.
However, Tobramycin can be inhaled to treat lung infections in patient with cystic fibrosis. Neomycin can be given orally to target certain bacteria in the GI system for patients experiencing hepatic encephalopathy (which will help lower ammonia levels) or before bowel surgery as prep.
How do they work?
It’s important to remember that antibiotic classes work in various ways. Some can inhibit the bacteria’s cell wall synthesis or nucleic acid synthesis, while others inhibit protein synthesis.
Aminoglycosides inhibit the bacteria’s protein synthesis.
How they do this is by targeting a specific structure within the bacteria’ cell structure called the ribosomes.
Ribosomes play a role in the process of making proteins (hence performing protein synthesis), and without successful protein synthesis, the bacteria can’t function and will die (which is what we want).
The bacteria’s ribosomes are made up of two subunits, a large and small one. The large subunit is called 50S, while the smaller one is called 30S. 30S is the subunit we care about for this review.
These two subunits work together to stack amino acids, which creates a polypeptide chain, hence the protein. Aminoglycosides affects this process by binding to the 30S ribosomal subunit (particularly the A-site). When it does this it causes the genetic information to not be read correctly which hinders the subunit’s ability to make healthy proteins. This results in the death of the bacteria.
It’s important to remember Aminoglycosides actually kill bacteria (they are bactericidal) rather than bacteriostatic (inhibit the bacteria’s growth).
Nursing Consideration for Aminoglycosides?
Check allergies before administering and obtain any ordered cultures.
Monitor peak and trough levels because they are powerful and can be toxic but we want them to be effective too:
- Peak level tells us the highest concentration of the medication in the blood.
- IM (intramuscular) administration: draw blood peak level 1 hour after injection
- IV (intravenous): draw blood peak level 30 minutes after infusion complete…typically a 30 minute infusion
- Trough level is the lowest concentration of the medication in the blood.
- This helps us monitor for toxicity. For IV and IM administration draw trough level right before next dose.
Effectiveness of the medication….is it working? WBC: normal 5,000–10,000 per mm3? Fever: decreased or gone? Other vital signs normal? No hypotension or tachycardia?
Remember these antibiotics are powerful and can cause toxicity that will affect the kidneys and hearing structures of the ears. Therefore, remember two types of toxicity that can be experienced with this class: Nephrotoxicity and Ototoxicity…remember amiNOglycoside
Nephrotoxic (toxic to the kidneys): can be reversed and factors that increase the risk of this are high dosages of the medication and using for too long
- Monitor:
- Urinary output (>30 mL/hr in adult)
- Renal function labs: BUN/creatinine
- BUN: 5-20 and Serum creatinine: 0.6–1.2 mg/dL
- GFR decreased less than 90mL/min
- This is the rate the glomerulus filters waste, ions, and water.
Ototoxicity (toxic to the ears): typically can’t be reversed and results from damage to the vestibular and cochlear parts of the ears
- Monitor for ringing in ear (tinnitus), hearing loss, dizzy, fullness in ears
- Increase risk for developing if patient is taking diuretics (like loop diuretics such as furosemide)
Aminoglycosides can also cause: neuromuscular blockade that results in muscle weakness and respiratory failure
- More likely to develop in patients who’ve received neuromuscular blocking meds like during anesthesia and or who have neuromuscular disorders like myasthenia gravis
Now test your knowledge with this free Aminoglycoside quiz.
References:
Block M, Blanchard DL. Aminoglycosides. [Updated 2022 Jul 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541105/
Gentamicin Injection, USP. U.S. Food and Drug Adminstration. (n.d.). Retrieved October 15, 2022, from https://www.accessdata.fda.gov/drugsatfda_docs/nda/2018/210303Orig1s000lbl.pdf
Werth, B. J. (2022, September). Aminoglycosides – infectious diseases. Merck Manuals Professional Edition. Retrieved October 15, 2022, from https://www.merckmanuals.com/professional/infectious-diseases/bacteria-and-antibacterial-drugs/aminoglycosides