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The adapted strain acquired resistance to not only chloramphenicol, but also cross-resistance to other antibiotics; [163] this was in contrast to the observation on the same strain, which was adapted to over 1000 generations under LSMMG, but without any antibiotic exposure; the strain in this case did not acquire any such resistance. [164]
Sometimes, whether an antibiotic is marked as resistant is also based on bacterial characteristics that are associated with known methods of resistance such as the potential for beta-lactamase production. [28] [20] Specific patterns of drug resistance or multidrug resistance may be noted, such as the presence of an extended-spectrum beta ...
[95] [96] The spread of antibacterial resistance often occurs through vertical transmission of mutations during growth and by genetic recombination of DNA by horizontal genetic exchange. [88] For instance, antibacterial resistance genes can be exchanged between different bacterial strains or species via plasmids that carry these resistance genes.
Antimicrobial resistance The misuse and overuse of antimicrobials in humans, animals and plants are the main drivers in the development of drug-resistant pathogens. [4] It is estimated that bacterial antimicrobial resistance (AMR) was directly responsible for 1.27 million global deaths in 2019 and contributed to 4.95 million deaths. [4]
For antibiotic resistance, which represents a widespread problem nowadays, drugs designed to block the mechanisms of bacterial antibiotic resistance are used. For example, bacterial resistance against beta-lactam antibiotics (such as penicillin and cephalosporins) can be circumvented by using antibiotics such as nafcillin that are not ...
Beta-lactamase provides antibiotic resistance by breaking the antibiotics' structure. 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.
Hence the residual organisms were not antibiotic resistant mutants but rather a subpopulation of what he called ‘persisters’. [7] The formation of bacterial persisters is now known to be a common phenomenon that can occur by the formation of persister cells prior to the antibiotic treatment [8] or in response to a variety of antibiotics. [9]
The antibiotic resistance genes found on the plasmids confer resistance to most of the antibiotic classes used nowadays, for example, beta-lactams, fluoroquinolones and aminoglycosides. [ 10 ] It is very common for the resistance genes or entire resistance cassettes to be re-arranged on the same plasmid or be moved to a different plasmid or ...