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Contents. Discovery and development of cephalosporins. Cephalosporins are a broad class of bactericidal antibiotics that include the β-lactam ring and share a structural similarity and mechanism of action with other β-lactam antibiotics (e.g. penicillins, carbapenems and monobactams). [ 1 ] The cephalosporins (and other β-lactams) have the ...
Any heterogeneous environment with respect to nutrient and antibiotic gradients may facilitate antibiotic resistance in small bacterial populations. Researchers hypothesize that the mechanism of resistance evolution is based on four SNP mutations in the genome of E. coli produced by the gradient of antibiotic. [175]
Bacterial resistance to these antibiotics primarily occurs through the production of β-lactamases, enzymes that hydrolyze the amide bond of the β-lactam ring, thereby eliminating the antimicrobial activity of these antibiotics. This resistance mechanism underscores the importance of the structural integrity of the β-lactam ring for the ...
These antibiotics all have a common element in their molecular structure: a four-atom ring known as a beta-lactam (β-lactam) ring. Through hydrolysis, the enzyme lactamase breaks the β-lactam ring open, deactivating the molecule's antibacterial properties. Beta-lactamases produced by gram-negative bacteria are usually secreted, especially ...
Tetracycline resistance is often due to the acquisition of new genes, which code for energy-dependent efflux of tetracyclines or for a protein that protects bacterial ribosomes from the action of tetracyclines. Furthermore, a limited number of bacteria acquire resistance to tetracyclines by mutations. [2] [5]
Horizontal gene transfer is the primary mechanism for the spread of antibiotic resistance in bacteria, [8] [5] [9] [10] and plays an important role in the evolution of bacteria that can degrade novel compounds such as human-created pesticides [11] and in the evolution, maintenance, and transmission of virulence. [12]
Kanamycin kinase. Aminoglycoside-3'-phosphotransferase (APH (3')), also known as aminoglycoside kinase, is an enzyme that primarily catalyzes the addition of phosphate from ATP to the 3'-hydroxyl group of a 4,6-disubstituted aminoglycoside, such as kanamycin. [2] However, APH (3') has also been found to phosphorylate at the 5'-hydroxyl group in ...
The resistome was first used to describe the resistance capabilities of bacteria preventing the effectiveness of antibiotics . [4] [5] Although antibiotics and their accompanying antibiotic resistant genes come from natural habitats, before next-generation sequencing, most studies of antibiotic resistance had been confined to the laboratory. [6]