120. Pharmacology | Beta-lactam Antibiotics, Other Cell Wall Inhibitors, and Cell Membrane-Active Antibiotics, Part 1: Penicillins & Beta Lactamase Inhibitors

A patient with a Klebsiella pneumoniae infection is found to have a KPC-producing strain. Which β-lactamase inhibitor is most likely to restore activity of the β-lactam antibiotic?

A. Clavulanic acid
B. Sulbactam
C. Tazobactam
D. Avibactam
E. None—KPC enzymes cannot be inhibited

D

Avibactam, vaborbactam, relebactam, and durlobactam inhibit Class A KPC carbapenemases.
The older BLIs (clavulanate, sulbactam, tazobactam) DO NOT inhibit KPC.

Why the other choices are wrong:

• A/B/C: Older suicide inhibitors only inhibit ESBL-type Class A, not KPC.

• E: Incorrect because newer BLIs DO inhibit KPC, especially avibactam.

Which of the following organisms is intrinsically resistant to all β-lactams because it lacks peptidoglycan and PBPs?

A. Streptococcus pneumoniae
B. Mycoplasma pneumoniae
C. Neisseria gonorrhoeae
D. Pseudomonas aeruginosa
E. Bacteroides fragilis

B

Mycoplasma has no cell wall, no peptidoglycan, and no PBPs, making it completely resistant to all β-lactams.
The transcript states this very explicitly in the atypicals section.

Why the other choices are wrong:

• A: Has peptidoglycan and PBPs—but may alter PBPs (PRSP).

• C: Can produce β-lactamases but still susceptible to some β-lactams.

• D: Highly resistant but not intrinsically β-lactam–proof; some β-lactams cover Pseudomonas.

• E: Anaerobe requiring BLI combinations—not intrinsically immune.

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