aminoglycoside
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What is an aminoglycoside?
Aminoglycosides are natural or semisynthetic compounds used to treat bacterial diseases. They consist of amino groups attached to glycosides (sugar derivatives).
They are effective against aerobic, gram-negative bacteria. Aminoglycosides bind to ribosomes, inhibiting protein synthesis and killing the bacterial cell. While most aminoglycosides target gram-negative bacteria like Escherichia coli and Pseudomonas aeruginosa, streptomycin and gentamicin also affect gram-positive organisms like Streptococcus and Staphylococcus.
Common aminoglycosides include gentamicin, tobramycin, and amikacin. They treat infections of the respiratory and urinary tracts, blood, abdominal cavity, and pelvic inflammatory disease. Due to poor gastrointestinal absorption, they are administered parenterally (intramuscular or intravenous injection) or topically.
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What are aminoglycosides used for in medicine?
Aminoglycosides are a class of antibiotics used to treat various bacterial infections. They are effective against aerobic, gram-negative bacteria by binding to ribosomes, which inhibits protein synthesis and kills the bacterial cell.
Common uses include treating meningitis, sepsis, and pneumonia. Specific aminoglycosides like gentamicin and tobramycin are used for these conditions, while amikacin treats infections resistant to other aminoglycosides. Neomycin is used for skin infections from wounds and burns. Streptomycin, often combined with other agents, treats plague, tularemia, and brucellosis.
However, the emergence of aminoglycoside-resistant organisms has limited their use in some infections. Enterobacter infections, for example, are treated with aminoglycosides, but drug resistance is increasingly common, especially in hospital settings.
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How do aminoglycoside antibiotics work to fight bacteria?
Aminoglycoside antibiotics combat bacteria by attaching to bacterial ribosomes, which are essential for protein synthesis. This inhibits protein production, leading to the death of the bacterial cell. These antibiotics are effective against aerobic, gram-negative bacteria, because these cells attract aminoglycosides and have specific transport mechanisms that facilitate the uptake of the drugs into the cells.
Examples of aminoglycosides include streptomycin and gentamicin, which possess some activity against gram-positive organisms. Aminoglycosides such as gentamicin and tobramycin are used to treat meningitis, sepsis, and pneumonia.
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Can you name some common examples of aminoglycoside antibiotics?
Aminoglycosides are antibiotics used to treat bacterial infections. They work by binding to bacterial ribosomes, which inhibits protein synthesis and kills the bacterial cell.
Examples of aminoglycosides include:
* Gentamicin: Used for infections of the respiratory and urinary tracts, blood, abdominal cavity, and pelvic inflammatory disease.
* Tobramycin: Also used for infections of the respiratory and urinary tracts, blood, abdominal cavity, and pelvic inflammatory disease.
* Amikacin: Commonly used for infections resistant to other aminoglycosides.
* Neomycin: Used to treat skin infections associated with wounds and burns.
* Streptomycin: Used with other agents to treat plague, tularemia, and brucellosis.2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are some side effects or risks of using aminoglycosides?
The aminoglycosides are administered via intramuscular or intravenous injection, or topically to the skin, because they are poorly absorbed from the gastrointestinal tract.
The toxicities associated with aminoglycosides can be severe and sometimes irreversible. The most common side effects are nephrotoxicity (impairment of kidney function) and ototoxicity (impairment of the organs of hearing and balance). The risk of these reactions increases with age and with pre-existing renal system diseases or hearing loss. The margin of safety between a toxic and a therapeutic dose is narrow.
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How do doctors decide when to use aminoglycosides instead of other antibiotics?
Doctors consider several factors when deciding to use aminoglycosides instead of other antibiotics. Aminoglycosides are often favored for infections caused by aerobic, gram-negative bacteria due to the way these cells attract and uptake aminoglycosides.
However, the emergence of aminoglycoside-resistant organisms can limit their use, and other antibiotics may be considered. Aminoglycosides can be used in combination with other antibiotics, like tetracyclines, to treat infections such as plague, tularemia, and brucellosis.
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aminoglycoside, any of several natural and semisynthetic compounds that are used to treat bacterial diseases. The term aminoglycoside is derived from the chemical structure of these compounds, which are made up of amino groups (―NH2) attached to glycosides (derivatives of sugar). The first aminoglycoside, the antibiotic streptomycin, was discovered in 1943 by American biochemists Selman Waksman, Albert Schatz, and Elizabeth Bugie, who isolated the compound from Streptomyces griseus, a strain of soil bacteria. Streptomycin was found to inhibit the growth of a variety of bacterial organisms, including the organism that causes tuberculosis (Mycobacterium tuberculosis). Waksman later isolated a second aminoglycoside, neomycin, from another species of soil bacteria, Streptomyces fradiae. In the following decades, natural aminoglycosides, such as gentamicin and tobramycin, and semisynthetic aminoglycosides, such as netilmicin and amikacin, were identified and developed.
Mechanism of action
Aminoglycosides are selectively active against oxygen-dependent (aerobic), gram-negative bacterial cells, since these cells possess the chemical characteristics that attract aminoglycosides and the specific transport mechanisms that facilitate the uptake of the drugs into the cells. Once inside bacterial cells, aminoglycosides exert their effects by binding to ribosomes, organelles that are fundamental to protein synthesis. As a result, protein synthesis is inhibited, and the bacterial cell dies.
Although most aminoglycosides are only effective against gram-negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa, the agents streptomycin and gentamicin possess some activity against gram-positive organisms, including Streptococcus and Staphylococcus. Though these agents generally are of little clinical significance when administered alone in gram-positive bacterial infections, they can produce synergistic effects (effects greater than those expected by the addition of agents) when used in combination with other types of antibiotics. The bacterial cell-killing effect of aminoglycosides is concentration-dependent, with high concentrations of drug having high rates of bacterial killing. The aminoglycosides also have a post-antibiotic effect, in which bacterial cell killing continues for a brief period of time after the blood plasma concentration of the antibiotic has fallen below the so-called minimal inhibitory concentration (the smallest amount of drug necessary to induce cell-killing effects).
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Clinical uses and toxicities
Aminoglycosides are used for a variety of infections. For example, gentamicin and tobramycin may be used in the treatment of meningitis, sepsis, and pneumonia; amikacin is commonly used in the treatment of infections that are resistant to other aminoglycosides; and neomycin is used in the treatment of skin infections associated with wounds and burns. Streptomycin is used primarily in combination with other agents, such as with tetracyclines in the treatment of plague, tularemia, and brucellosis. Gentamicin has largely replaced streptomycin in the treatment of bacterial endocarditis, which typically involves combination therapy with penicillin. The emergence of aminoglycoside-resistant organisms has limited the use of these drugs in the treatment of certain infections. For example, streptomycin was widely used in the treatment of tuberculosis, but the emergence of streptomycin-resistant tubercle bacilli led to the replacement of streptomycin with different types of antibiotics.
The aminoglycosides are poorly absorbed from the gastrointestinal tract and therefore are given parenterally, via intramuscular or intravenous injection, or topically, via application to the skin. The toxicities associated with aminoglycosides are severe and are sometimes irreversible, and the margin of safety between a toxic and a therapeutic dose is narrow. Nephrotoxicity (impairment of kidney function) and ototoxicity (impairment of the organs of hearing and balance) are the most common side effects of aminoglycosides. The risk of these reactions increases with age and with preexisting renal system diseases or hearing loss. Once-a-day dosing allows the plasma level of the drug to fall below toxic levels and does not reduce the antibacterial effect.