Aminoglycosides: Action, What They Are, Activity Spectrum, Administration and Specific Agents
Aminoglycosides action is effective in killing certain types of bacteria. This group of antibiotics includes amikacin, kanamycin, netilmicin, streptomycin, apramycin, gentamicin, neomycin, paromomycin, and tobramycin. Aminoglycocides that are derived from micromonospora will have the -micin suffic and those derived from Streptomyces will have the -mycin suffix.
Mechanism of Action
Aminoglycosides action include a large variety of antibiotic mechanisms, some as protein synthesis inhibitors. However, their exact mechanism of action is not exactly understood or fully known. Such mechanisms may include:
- Interfering with the proofreading process, in turn, increasing the rate of error in premature termination synthesis.
- Disrupting a bacterial cell membrane’s activity.
- Peptidyl-tRNA traveling from the A-site to P-site through the inhibition of ribosomal translocation.
Spectrum of Activity
These antibiotics are most often used to treat infections involving aerobic, gram-negative bacteria, such as Acinetobacter, Pseudomonas, and Enterobacter. In some cases, certain microbacteria, like the bacteria responsible for causing tuberculosis, are vulnerable to this type of antibiotic. Aminoglycosides are most often used as empiric therapy for serious infections, including complicated intra-abdominal infections, nosocomial respiratory tract infections, septicemia, and complicated urinary tract infections. This type of antibiotic is mostly unable to treat fungi, anaerobic bacteria, and viruses.
Toxicity
Since aminoglycocides can cause damage to balance or hearing functions, or kidney toxicity, the dose is determined by the patient’s body weight. During a course of treatment with this type of antibiotic, the patients creatinine and blood drug levels are monitored. The serum creatinine measurements are done in order to estimate kidney function, specifically how well they are functioning, and as a marker of aminoglycoside-related kidney damage. These antibiotics can be dangerous, and when used, will be used with great care and the patient will be heavily monitored.
How are Aminoglycosides Administered?
This type of antibiotic is administered either intramuscularly or intravenously because these drugs are not absorbed well when administered orally. In some cases, this antibiotic can be applied topically to kill bacteria in wounds. To decontaminate the gut, this type of antibiotic can be administered orally. Tobramycin, an aminoglycoside antibiotic, can be given in a nebulized form.
Specific Agents
In 1943, streptomycin, the first aminoglycoside antibiotic, was isolated from Streptomyces griseus. Neomycin worked better against aerobic gram-negative bacteria bacilli than streptomycin did, but it could not be safely used systemically due to its formidable toxicty. Neomycin was isolated from Streptomyces fradiae. In 1963, gentamicin was isolated from Micromonospora. This aminoglycoside was considered a breakthrough in how gram-negative bacillary infections were treated, including the infections that were caused by Pseudomonas aeruginosa. Other aminiglycosides were later developed, including netilmicin, tobramycin, and amikacin which are all currently available and currently used systemically.
Resources
Barrett, J. (2002). Aminoglycosides Health Article. Retrieved on June 23, 2010 from Healthline: https://www.healthline.com/galecontent/aminoglycosides
The Merck Manuals Online Medical Library. (2009). Aminoglycosides. Retrieved on June 23, 2010 from The Merck Manuals Online Medical Library: https://www.merck.com/mmpe/sec14/ch170/ch170b.html
Image Credits
Syringe and Vial: zeathiel – sxc.hu
