BACTERIAL RESISTANCE TO ANTIMICROBIAL DRUGS ACTIONS

Bacteria has the ability to produce protein that help them resist antimicrobial drug actions.

 .Some bacteria produce beta-lactamase enzymes that inactivate penicillin and cephalosporins.

 .Some bacteria produce proteins that prevent drugs from penetrating the bacterial membrane or proteins through the bacterial membrane.

 .When bacterial resistance occurs other drugs must be used to treat the infection.

  What is antibiotic resistance?
 Is a type of drug resistance where a microorganism is able to survival exposure to an antibiotic. The primary cause of antibiotic resistance is Genetic mutation in bacteria. If a bacterium carries several resistance genes, it is called MULTIRESISTANT, informally a super burg or super bacterium.

  MECHANISMS OF RESISTANCE ANTIMICROBIAL DRUGS. 
 The five main mechanisms by which microorganisms exhibit resistance to antimicrobial drugs are:

 1.Drug inactivating enzymes or modification.
.Some organisms produce enzymes that chemically modify drugs forexample, enzymatic deactivation of Penicillin G in some penicillin-resistant bacteria through the production of beta lactamases.

 2.Target mimicry.
.This involves the production of protein that bind sequester drugs, preventing the drugs from binding to their target, example Mycobacterium Tuberculosis produces a protein with regular pectapeptide repeated that appear to mimic the structure of DNA, this protein binds fluoroquinolones sequestering them and keeping them from binding to DNA, providing M.tuberculosis resistance to Fluoroquinolones.

 3.Alternation of target molecule(site). .Minor structural changes in antibiotic target can prevent binding. .Changes in ribosomal RNA prevent macrolide from binding to ribosomal subunits.

 4.Alternation of metabolic pathway. .Forexample, some sulfonamide-resistant bacteria do not require para aminobenzoic acid (PABA), an important precursor for the synthesis of folic acid and nucleic acids in bacteria inhibited by sulfonamides. Instead, like mammalian cells, they turn to utilizing preformed folic acid.

 5.Reduced drug accumulation.
 .By decreasing drug permeability or increasing active efflux (pumping out) of the drugs across the cell surface.

 .Decreased uptake of the drug,leads into alteration in porin proteins, decrease permeability of cells also prevents certain drugs from entering.

 .Increased elimination of the drug lead into increases overall capacity of organism to eliminate drug, enables organism to resist higher concentration of drugs and Tetracycline resistance.