Question

Match List I with List II:
List I
A. Acid-resistant alternative to penicillin G
B. Penicillinase-resistant penicillin
C. Extended spectrum penicillin
D. $\beta$-lactamase inhibitor
List II
I. Methicillin
II. Penicillin V
III. Tazobactam
IV. Ampicillin
Choose the correct answer from the options given below:

• A. A-II, B-I, C-IV, D-III
• B. A-IV, B-III, C-II, D-I
• C. A-III, B-IV, C-II, D-I
• D. A-IV, B-II, C-III, D-I

Hint:

To remember this classification, associate Penicillin V with "V" for "Vigorously acid-stable" (oral use), and Tazobactam with "bactam" indicating its role as a suicide inhibitor of $\beta$-lactamases.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
$\beta$-lactam antibiotics, which include penicillins and cephalosporins, share a core $\beta$-lactam ring structure essential for their antibacterial activity.
They work by binding to Penicillin-Binding Proteins (PBPs), which inhibits bacterial cell wall peptidoglycan synthesis.
Due to the development of bacterial resistance mechanisms, particularly the production of $\beta$-lactamase enzymes, several modifications to the basic penicillin structure have been developed.

Step 2: Detailed Explanation:
Let us match the characteristics with the corresponding drug molecules:
1. Acid-resistant alternative to penicillin G (A):
Penicillin G (benzylpenicillin) is highly unstable in the acidic environment of the stomach and must be administered parenterally.
Penicillin V (phenoxymethylpenicillin) (II) is structurally modified to be acid-resistant, allowing for effective oral administration.
Thus, A matches with II.
2. Penicillinase-resistant penicillin (B):
Many bacteria produce penicillinase (a specific $\beta$-lactamase) that cleaves the $\beta$-lactam ring of standard penicillins.
Methicillin (I) is structurally modified with bulky side chains that sterically hinder the penicillinase enzyme, making it resistant to degradation.
Thus, B matches with I.
3. Extended spectrum penicillin (C):
While natural penicillins primarily target Gram-positive bacteria, extended-spectrum aminopenicillins, represented by Ampicillin (IV), can penetrate the outer membrane of Gram-negative bacteria, widening their therapeutic spectrum.
Thus, C matches with IV.
4. $\beta$-lactamase inhibitor (D):
These compounds contain a $\beta$-lactam-like ring that binds irreversibly to bacterial $\beta$-lactamase enzymes, protecting co-administered penicillins from degradation.
Tazobactam (III) is a potent, irreversible $\beta$-lactamase inhibitor commonly combined with piperacillin.
Thus, D matches with III.
Combining these matches, we get: A-II, B-I, C-IV, D-III.

Step 3: Final Answer:
The correct matching sequence is A-II, B-I, C-IV, D-III.
Therefore, the correct option is (A).