Question

31.

Which of the following is an example of intrinsic resistance?

A strain of previously non drug–-resistant Bacillus subtilis acquires a ciprofloxacin resistance gene as a result of genetic transformation with a plasmid containing the drug-resistance gene.

A strain of previously non-drug-resistant Escherichia coli receives an amoxicillin resistance gene during conjugation with a drug-resistant strain of Escherichia coli.

The bacterium Staphylococcus aureus acquires a mutation in the ribosomal binding site for the antimicrobial drug tetracycline.

The bacterium Bacillus cereus produces endospores during environmentally harsh conditions, enabling it to survive cooking processes.

Which of the following are primary mechanisms through which microorganisms evade antimicrobial drugs? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.

Drug target alterations

Drug inactivation

Reducing drug concentration inside of the cell

Decreasing intracellular drug solubility

Answer 1

Correct answer is :The bacterium Bacillus cereus produces endospores during environmentally harsh conditions, enabling it to survive cooking processes.

Reason:Intrinsic resistance refers to a natural mode of resistance in microorganisms that is via activity of the outer membrane as seen in gram negative bacteria that do not allow the antibiotic/drug to cross through the outer membrane. Another method of intrinsic resistance is via spore formation /endospores that are resistant to any harsh environmental conditions.

Correct answers are:

• Drug target alterations
• Drug inactivation
• Reducing drug concentration inside of the cell

Reason:The targets of the drugs are usually altered by the microorganisms.This may include alteration of some proteins that are a target for the drug.Some times, the drug may be inactivated by enzymatic degradation;also the  membrane permeability for the drug can be changed thus reducing its concentration in the interior of the cell.