Question

Due to use of penicillin and its derivatives which enzyme is expressed by strains of pathogenic bacteria and is responsible for bacterial resistance to antibiotics ?

• A. Transpeptidase
• B. \(\beta\)-lactamase
• C. Penicillinase
• D. Muramidases

Hint:

To counter \(\beta\)-lactamase-mediated resistance, clinicians use combination therapies that pair a \(\beta\)-lactam antibiotic with a \(\beta\)-lactamase inhibitor, such as clavulanic acid.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Penicillin and its derivatives are \(\beta\)-lactam antibiotics that disrupt bacterial cell wall synthesis.
They bind to and inhibit the bacterial enzyme transpeptidase, which is responsible for cross-linking peptidoglycan chains.
In response to antibiotic exposure, bacteria develop resistance mechanisms, often by producing enzymes that degrade the antibiotic.

Step 2: Detailed Explanation:
The defining chemical feature of penicillin and its relatives is the four-membered \(\beta\)-lactam ring.
The primary mechanism of resistance in many pathogenic bacteria involves the expression of \(\beta\)-lactamase enzymes.
These enzymes catalyze the hydrolytic cleavage of the amide bond in the \(\beta\)-lactam ring, converting the active antibiotic into an inactive derivative (such as penicilloic acid) that can no longer bind to transpeptidase.
- Penicillinase (Option C) is a specific sub-class of \(\beta\)-lactamases that targets penicillin specifically.
- \(\beta\)-lactamase (Option B) is the broad and standard term for this family of resistance enzymes, which includes penicillinases, cephalosporinases, and carbapenemases.
Because \(\beta\)-lactamase is the comprehensive name for the class of enzymes responsible for resistance to penicillin and its structural derivatives, it is the correct answer.

Step 3: Final Answer:
The enzyme expressed by resistant strains of pathogenic bacteria is \(\beta\)-lactamase.