Genetic of Resistance
Bacteria posses a remarkable number of genetic mechanisms for resistance to microbials. They can undergo chromosomal mutations, express a latent chromosomal resistance gene, or acquire new genetic resistance material through direct exchange of DNA (by conjugation), through a bacteriophage (transduction), through extrachromosomal plasmid DNA via transformation. The information encoded in this genetic material enables a bacterium to develop resistance through three major mechanisms: production of an enzyme that will inactivate or destroy the antibiotic; alteration of the antibiotic target site to evade action of the antibiotic; or prevention of antibiotic access to the target site.
Examples of organisms that are known to possess resistance mechanisms of the various types are shown in tables, together with the genetic mechanism for the resistance. It is not unusual for a single bacterial strain found in a hospital to possess several of these resistance mechanisms simultaneously.
Modified from : Neu HC. The Crisis in antibiotic resistance. Science 1992;257
No comments:
Post a Comment