- May 04, 2018 -
In livestock and poultry farming, aminoglycoside antibiotics are not as concerned as florfenicol, tilmicosin, amoxicillin, and colistin sulfate. However, the unique bactericidal action mechanism of these antibiotics and their excellent synergistic and synergistic effects with other drugs are indispensable for the entire family of antibacterial drugs. At present, in the catalog of available animal drugs, there are mainly streptomycin sulfate, kanamycin sulfate, gentamicin sulfate, neomycin sulfate, apramycin sulfate, and spectinomycin sulfate. They are divided into two categories according to natural and semi-synthetic.
Drug antibacterial mechanism
The antibacterial mechanism of aminoglycoside antibiotics is mainly through the inhibition of multiple stages in the ribosome cycle of bacteria: the initial stage of protein biosynthesis, the peptide chain extension stage and the termination stage. These processes inhibit the protein synthesis of bacteria and achieve rapid sterilization effect.
Aminoglycoside antibiotics can also be attached to the membrane of the bacteria surface by ion adsorption, resulting in cell membrane defects, increased permeability, leakage of vital substances in the bacterial cells, and rapid death of bacteria. Therefore, the central role of aminoglycoside antibiotics is "inhibition of protein synthesis" and ion-like "cracking" of cell membranes.
Aminoglycosides are fast-acting fungicides. They mainly have a strong bactericidal effect on quiescent bacteria. Therefore, these antibiotics are also called bactericidal fungicides.
Antibacterial spectrum of drugs
Aminoglycoside antibiotics only have a strong bactericidal effect against aerobic gram-negative bacteria (including Pseudomonas aeruginosa) but have a poorer effect on gram-positive bacteria (can be considered clinically ineffective), against enterococci and anaerobic The bacteria are naturally resistant. Among them, streptomycin sulfate is an exception and it is effective against Yersinia pestis and Mycobacterium tuberculosis.
When bacteria contact with a certain concentration of aminoglycoside antibiotics, such antibiotics have a persistent inhibitory effect on bacterial growth (ie, PAE) when the antibiotic concentration drops below MIC or disappears. Therefore, aminoglycoside antibiotics have obvious PAE for gram-negative bacilli such as Escherichia coli, Salmonella, Pasteurella, etc., and should be considered when combining veterinary treatment of animals and poultry for clinical administration (prescription).
Drug resistance mechanism
The resistance mechanism of aminoglycoside antibiotics: First, drug-resistant bacteria produce inactivating enzymes (acetylase, adenylylase, phosphorylase) to inactivate the drug; second, the resistance of the cell wall of resistant bacteria sexual changes lead to abnormal transport of drugs into the cell. Third, drug-resistant bacteria modify antibiotics to target protein (Enterococci, Mycobacterium tuberculosis), thereby evading the effects of drugs.
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