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Aminoglycosides are, in other words, bactericidal aminoglycoside antibiotics, which are characterized by a rather poor penetration into the tissues. For this reason, the spectrum of their action is limited. Antibiotics should be administered parenterally due to their poor absorption via the digestive system.
What are aminoglycosides?
Mostly aminoglycozydy are natural substances with antibacterial properties propertieswhich produce actinomycetes of the genus Streptomyces and Micromonospora. Original derivatives of the genus Micromonospora are e.g. neomycin, paromomycin, tobramycin. There are also semi-synthetic derivatives aminoglycosidessuch as: amikacin, dibecacin, netilmicin. Aminoglycozydy is divided into three basic groups:
- streptomycin group (streptomycin, spectinomycin),
- neomycin group (neomycin, paromomycin),
- the kanamycin group that is most commonly used clinically (gentamicin, amikacin, netilmicin, tobramycin).
Action of aminoglycoside antibiotics
Effectiveness aminoglycosides depends on their concentration. The higher the concentration provides the stronger the action of the antibiotic, while the effect may persist even for some time after the blood concentration of the drug has dropped significantly. Aminoglycozydy remain in the blood serum for about 2 hours. Due to its chemical structure aminoglycozydy they have properties antibacterial, and their action can take place in several ways. A positive charge causes them to bind to negatively charged lipopolysaccharides of the bacterial cell walls and other intracellular anionic molecules, such as RNA, DNA or phospholipids. Action aminoglycoside antibiotics it causes the death of bacterial cells. Aminoglycozydy cause translation disruption by binding to the 30S subunit of the bacterial ribosome or to ribosomal proteins. Transport in anaerobic conditions and at low pH aminoglycosides into the bacterial cell is inhibited.
Another way to act aminoglycoside antibiotics there is a disintegration of the cell membrane and an increase in its permeability to ions and a disturbance in the synthesis of DNA and RNA in the bacterial cell. Aminoglycozydy Compared to beta-lactam antibiotics, they have a narrower spectrum of activity against bacteria, but to a lesser extent they cause resistance among bacteria. They are opposed aminoglycoside antibiotics using three mechanisms. First, microbes can modify aminoglycozydy by plasmid-encoded enzymes. In other cases, by activating the antibiotic elimination pump, the drug transport to the inside of the bacterial cells is reduced. Also, due to mutations in bacterial DNA, the affinity of the 30S ribosomal subunit for the antibiotic and the 16S ribosomal RNA and ribosomal proteins may be reduced.
The use of aminoglycosides
Aminoglycozydy They are used primarily in the fight against aerobic gram-negative bacilli and bacterial strains such as: S. aureus, S. epidermidis, P. aeruginosa and M. tuberculosis. However, they are not used in the fight against anaerobic bacteria and due to poor penetration into many structures of the body, including the cerebrospinal fluid, they are not used in the treatment of meningitis. In the case of gram-positive cocci aminoglycozydy must be combined – for the best effectiveness – with beta-lactam antibiotics and vancomycin, which disrupt the synthesis of the bacterial cell wall. Aminoglycoside antibiotics It is used mainly in the treatment of severe infections with gram-negative bacteria, such as hospital infections, sepsis, systemic infections and infections that are complications of burns. Streptomycin is used in the treatment of tuberculosis, plague or tularemia. Drugs from the kanamycin group (amikacin, netilmicin, gentamicin) are used for pneumonia and sepsis. Paranomycin has the best effect in the fight against bacterial dysentery, while neomycin is used in the treatment of wounds, ulcers, burns and dermatoses. The last derivative, spectinomycin, is used to treat gonorrhea.
Side effects with the use of aminoglycoside antibiotics
Each drug can cause some side effects or side effects. It is no different in the case of aminoglycosideswhich are quite nephrotoxic and ototoxic, especially for young children and the elderly. In the first case, they can damage the kidney parenchyma cells and cause renal tubular necrosis. Of this type side effects they occur after about 5 days after antibiotic treatment. symptoms however, they are reversible and regeneration occurs as a result of drug discontinuation. In the second case, hearing and balance may be impaired as a result of damage to the inner ear, because aminoglycozydy cause damage to the labyrinth ciliate cells. Aminoglycoside antibiotics they can also be responsible for disorders of neuromuscular transmission, problems with the circulatory system, rash, increase in body temperature and ailments with the digestive system.