Mechanisms of Resistance
Antibiotic resistance genes are acquired via four major mechanisms—spontaneous mutation, conjugation (transfer of plasmid), transformation (transfer of free DNA), or transduction (transfer by viral delivery). Spread may be vertical (i.e., generation to generation of the same species) or horizontal (i.e., across species or even genera). With prolonged or inappropriate antibiotic use, antimicrobial-resistant strains are selected for survival compared to non-resistant strains, leading to a dominance of the former within the micro-environment.
The genetic elements endow the bacterium with a number of resistance modalities. Some genes encode enzymes that alter or destroy the antibiotic. Others upregulate or modify the target enzyme or metabolic process that the antibiotic attacks. This allows the bacterium to go unrecognized in the presence of the antibiotic. Other genetic elements decrease the permeability of the organism for the antibiotic (decreased uptake) or encode efflux pumps that extrude the antibiotic once it has entered the organism.
Skin Therapy Letter. 2013;18(5) © 2013 SkinCareGuide.com