Question

1. List 3 mechanisms of antibiotic resistance. (3pts)

-Antimetabolite action (inhibit nucleic acid synthesis or function)

-Alteration of cell membranes (Inhibit cell wall synthesis of function)

-Inhibition of protein synthesis

2. For the 3 mechanisms, you listed above, list an example, and the antibiotic the organism has become resistant to. (6pts)

Answer 1

A) 3 mechanism of antibiotic resistance are mentioned below along with the mechanism and example

1) by preventing the antibiotic reaching to the target inside the cell.

Some of the microorganism develop pump on this cell membrane and pump the drug out side of cell by using ATP. Thus they decreased concentration of antibiotic reaching inside to the target molecules and cause antibiotic resistance. Ex XDR resistance Tuberculosis, they develop pump on their wall and become antibiotic resistant.

2) resistance due to destroying of antibiotics.

Some of the enzyme present in bacteria can cleave antibiotic.

Example is beta lactamase gene , produce beta lactamase protein and cleave beta lactum antibiotic. Antibiotic penicillin has beta lactum as an active component thus by degradation of this component , bacteria becomes resistant to it.

3) resistance due to expression of alternative proteins

Some bacteria produce alternative proteins , which are inhibited by the antibiotic instead of actual proteins. For example, acquiring of resistance gene mecA in Staphylococcus aureus . Product of this gene is required for synthesis of cell wall. This gene  produce a new penicillin-binding protein which has low affinity to beta lactum antibiotics. These proteins are needed for bacterial cell wall synthesis. new penicillin-binding protein due to low affinity to antibiotics is less resistant to the drugs. Thus leads to survival of bacteria  upon  treatment.