After having established the relevant rise of bacterial resistance to conventional antimicrobials and the decrease in the spectra of inhibitory action that certain microorganisms present, it is necessary to determine and know which are the mechanisms of action that bacteria present, especially those that are ** gram negative ** in view that they cause the greatest clinical suffering.
There are many mechanisms of action that gram-negative microorganisms have, their resistance is generally attributed to four specific mechanisms:
1. Enzymatic modification of the antibiotic: Enzymes are produced in bacteria capable of modifying the structures of antibiotics, causing them to lose their main function.
2. Output pumps: these pumps act in the periplasmic space and expel the antibiotic to the outside, thus preventing it from reaching its action site.
Exit pumps are present in all microorganisms (bacteria, fungi, parasites), and have been highly studied for being one of the primary factors causing the resistance of bacteria to antibiotics. The main function of the exit pumps is the expulsion of toxic agents from the cell, among them the antibiotics.
3. Changes in the permeability of the outer membrane: the bacteria generate changes in the lipid bilayer. The permeability of the cell membrane is modified by changes in the porins.
Porins are proteins that form channels filled with water through which some elements, including antibiotics, enter and leave the cellular space. these molecules can also delay the effect of the antibiotic and their access to the cell interior.
4.-Alterations of the site of action: bacteria are able to modify the site where antibiotics act and not allow them to fulfill their function.
The mechanisms of resistance to antibiotics of gram-negative bacteria are basically the exit pump, the closure of the porins, the mutations and transformations in the action sites and the hydrolytic enzymes work harmoniously to defend the bacterium from the antibiotic and therefore of his death. Source
