Aminoglycoside antibiotics are used to treat serious infections caused by
Some commonly used aminoglycosides include: amikacin (Amikin®); apramycin;
capreomycin; gentamicin (Garamycin®); kanamycin (Kantrex®); neomycin (Mycifradin®); netilmicin (Netromycin®); paromomycin (Humatin®);
streptomycin; tobramycin (TOBI Solution®, TobraDex®, Nebcin®)
Mode of Action
Although aminoglycosides stop bacteria from making proteins, it is uncertain whether this is the action that results in bacterial cell death.
Disruption of Protein Synthesis
Aminoglycosides bind to the bacterial 30S ribosomal subunit. Ribosomes are the protein factories of cells. They are composed of two subunits in bacteria, a 30S and a larger 50S. By binding to the ribosome, aminoglycosides inhibit the translocation of tRNA during translation and leaving the bacterium unable to synthesize proteins necessary for growth.
Although the eukaryotic cells of humans also have ribosomes, these cellular protein factories differ in size and structure from the ribosomes of prokaryotes. That is why aminoglycosides do not interfere with protein synthesis in human cells.
Bacterial Cell Wall Damage
It may not be the inhibition of protein synthesis that produces the bactericidal (bacteria killing) effect. Aminoglycosides also appear to displace cations in the bacterial cell biofilm that are responsible for linking the lipopolysaccharide (LPS) molecules characteristic of Gram-negative bacterial cell walls.
This creates holes in the cell wall that may kill the bacteria before the aminoglycoside even reaches the ribosome. Because our cells do not have cell walls (some of the chemical structural components of the bacterial cell wall are found only bacteria) human cells are not susceptible to these destructive actions.
Type of Infection Aminoglycosides Are Used Against
Aminoglycosides are most often used in empiric therapy (treatment initiated before a firm diagnosis is made) for serious infections including septicemia, complex infections within the abdominal cavity, severe urinary tract infections, and nosocomial (hospital acquired) respiratory infections.
Because of their toxicity, aminoglycosides are only given for only a short period of time. Less toxic antibiotics are substituted once the causative agent of infection is positively identified.
Antimicrobial Spectrum of Aminoglycosides
Gram-negative Aerobic Bacteria: Aminoglycosides exert their antibiotic effect against aerobic (oxygen requiring), gram-negative bacteria, including Pseudomonas, Acinetobacter, and Enterobacter.
Gram-positive Bacteria: Gram-positive bacterial infections can also be treated with aminoglycosides, but are typically not used because of the toxicity. Aminoglycosides have a synergistic effect when combined with beta-lactam antibiotics (penicilins) and have been used to treat streptococcal infections. The ampicillin (a beta-lactam antibiotic) gentamicin combination is referred to as "amp and gent" or "pen and gent" for penicillin and gentamicin.
Mycobacteria: Some species of Mycobacteria, including the causative agent of tuberculosis, are also susceptible to aminoglycosides.
Adverse Effects of Aminoglycosides
Because aminoglycosides are quickly broken down in the stomach, these antibiotics can't be given orally, but instead must be injected.
The adverse effects of aminoglycosides include potential damage to the ears and kidneys. The risk can be reduced by monitoring blood levels of the drug and maintaining the dose at levels that will kill bacteria without causing harmful side effects.
* The information in this article is not meant to be used for self-diagnosis or treatment of illness. If you are sick, seek help from a trained medical professional, not a computer.