Question

Resistance occurs in the bacterial organisms via

A. Efflux pumps

B. Failure to penetrate the organism

C. Changes in target enzymes

D. No change in target enzymes

Choose the correct answer from the options given below.

• A. A, B and D only
• B. B, C and D only
• C. A, B and C only
• D. A, C and D only

Hint:

Remember the major mechanisms of antimicrobial resistance as: decreased entry, increased efflux, target modification, drug inactivation, and metabolic bypass.
For multiple-response questions, efflux pumps and failure of drug penetration are classic resistance mechanisms.
Also remember that alteration of the drug target is a major mechanism, so an option stating “no change in target” is usually incorrect when target modification is being tested.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Bacterial antimicrobial resistance occurs when bacteria develop mechanisms that reduce or completely prevent the effectiveness of an antimicrobial drug.
The major mechanisms include decreased drug entry, active removal of the drug by efflux pumps, modification of the antimicrobial target, enzymatic inactivation of the drug, and alternative metabolic pathways.
Therefore, the statements must be evaluated according to the recognized mechanisms by which bacteria resist antimicrobial agents.
Detailed Explanation:
Statement A: True.
Efflux pumps are an important mechanism of bacterial antimicrobial resistance.
These membrane-associated transport systems actively remove antimicrobial agents from inside the bacterial cell.
As a result, the intracellular concentration of the drug becomes insufficient to produce its antimicrobial effect.
Efflux pumps can contribute to resistance against several classes of antimicrobial agents.
Statement B: True.
Failure of an antimicrobial agent to penetrate the bacterial organism can result in resistance.
Bacteria may reduce the entry of drugs by altering membrane permeability or modifying or reducing the number of channels through which the drug normally enters.
This mechanism is particularly important for drugs that require specific porins or transport systems to enter bacterial cells.
Reduced penetration consequently prevents the antimicrobial agent from reaching an effective concentration at its target site.
Statement C: True.
Changes in target enzymes or other antimicrobial targets are another important mechanism of bacterial resistance.
A bacterium may alter the structure of the target so that the antimicrobial agent can no longer bind effectively.
For example, alteration of enzymes involved in important metabolic pathways can reduce the binding or inhibitory action of a drug.
Such target modification allows the bacterium to continue its normal biological processes despite the presence of the antimicrobial agent.
Statement D: False.
Resistance may occur precisely because of changes in target enzymes or target structures.
Therefore, saying that there is “no change in target enzymes” does not represent the resistance mechanism described in the question.
Target modification is a recognized mechanism by which bacteria become less susceptible to antimicrobial agents.

Step 3: Final Answer:
Statements A, B, and C represent recognized mechanisms of bacterial antimicrobial resistance.
Statement D is incorrect because modification of antimicrobial targets, including target enzymes, can contribute to resistance.
Hence, the correct answer is (C) A, B and C only.