Which of the following is NOT a direct mode of action of antimicrobial drugs?

• A. Stimulation of host immune response
• B. Inhibition of protein synthesis
• C. Disruption of plasma membrane integrity
• D. Inhibition of cell wall synthesis

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what is meant by 'direct mode of action' of antimicrobial drugs. This refers to the specific biochemical or structural target within the microorganism that the drug acts upon to inhibit or kill it.
2. Step 2: Review the common direct modes of action of antimicrobial drugs, which typically include inhibition of protein synthesis, disruption of plasma membrane integrity, and inhibition of cell wall synthesis. These actions directly affect microbial cells.
3. Step 3: Analyze the option 'Stimulation of host immune response' and recognize that this does not directly target the microorganism itself, but rather enhances the host's defense mechanisms indirectly.
4. Step 4: Compare all options and identify that 'Stimulation of host immune response' is not a direct antimicrobial action because it does not involve direct interference with microbial structures or functions.
5. Step 5: Conclude that the correct answer is the option that represents an indirect effect, which is 'Stimulation of host immune response', distinguishing it from the other direct mechanisms listed.