Question

What are two ways by which bacteria can overcome (or avoid) the effects of antibiotics? (i.e., list 2 things bacteria can do to antibiotics to make them not work)- 4pts

Answer 1

Antibiotics leads to the disruption of essential structures or processes in bacteria.thus killing the bacteria .Hence bacteria have evolved many antibiotic resistance mechanisms to withstand the actions of antibiotics. Bacteria can withstand the effects of an antibiotic in two main ways:

1. By stopping the antibiotic from reaching its target with a high concentration.

There are different ways in which a bacteria can try to stop the antibiotic from entering its system or can attack the antibiotic. Some of them are given below :

a. By pumping the antibiotic out from the bacterial cell : Specific pumps can be produced by the bacteria that sit in their membrane or cell wall. Which can transport antibiotics out from the bacterium, in this way the antibiotic concentration inside the bacterial cell can be lowered. In some kinds of mutations the bacteria produce more pumps, which in turn increases resistance.

b. Decrease in the permeability of the membrane surrounding the bacterial cell : Bacteria can change its membrane in such a way that it becomes difficult for antibiotics to pass throught , thus less of the antibiotic gets into the bacteria.

c. Destroy the antibiotic: The bacteria can produce some enzymes that can inactivate antibiotics. Eg β-lactamase that destroys the β-lactam ring of penicillins.

d. Modification of the antibiotic itself:    Some enzymes produced by bacteria can add different chemical groups to the antibiotics. This in turn prohibits binding between the antibiotic and its target in the bacterial cell.

2. Modification of the target of the antibiotic : Sometimes the bacteria makes changes on the specific target on which the antibiotic is set to act. Some of the ways are :

a. Camouflaging the target : Due to mutation some changes may occur in the composition or structure of the target like adding some chemical groups in the bacterium which can stop the antibiotic from interacting with the target. Thus bacteria shielding it from the antibiotic.

b. Expression of alternative proteins. Production of alternative proteins instead of the ones that are inhibited by the antibiotic. Example, the Staphylococcus aureus can acquire the resistance gene mecA and produce the protein required for cell wall production , which is a a new penicillin-binding which is less likely to bind to the antibiotic but performs its functions.

c. Reprogram target : Bacteria can also produce a different variant of a structure it needs. For example, Vancomycin-resistant bacteria make a different cell wall compared to susceptible bacteria. The antibiotic is not able to interact as well with this type of cell wall.

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