β-Lactamase inhibitors – mechanism and examples MCQs With Answer

β-Lactamase inhibitors – mechanism and examples MCQs With Answer
β-Lactamase inhibitors are drugs that protect β-lactam antibiotics by inhibiting bacterial β-lactamase enzymes. They act by forming covalent or reversible complexes with enzymes (suicide inhibitors like clavulanic acid, or non-β-lactam DBOs like avibactam), broadening activity against ESBL, AmpC and some carbapenemases (KPC). Key examples include clavulanic acid, sulbactam, tazobactam, avibactam, vaborbactam and relebactam; notable combinations are amoxicillin‑clavulanate, piperacillin‑tazobactam, ceftazidime‑avibactam and meropenem‑vaborbactam. Understanding mechanisms, spectrum and resistance (MBLs, porin loss, enzyme mutation) is essential for rational therapy. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary mechanism of action of β-lactamase inhibitors?

• They directly kill bacteria by disrupting cell membranes
• They inhibit bacterial protein synthesis
• They bind to and inactivate β-lactamase enzymes, protecting β-lactam antibiotics
• They act as efflux pump inhibitors

Correct Answer: They bind to and inactivate β-lactamase enzymes, protecting β-lactam antibiotics

Q2. Clavulanic acid is best described as which type of β-lactamase inhibitor?

• A non‑β‑lactam diazabicyclooctane (DBO)
• A cyclic boronic acid inhibitor
• A β‑lactam suicide (irreversible) inhibitor with weak intrinsic antibacterial activity
• A metallo‑β‑lactamase chelator

Correct Answer: A β‑lactam suicide (irreversible) inhibitor with weak intrinsic antibacterial activity

Q3. Which of the following is a non‑β‑lactam diazabicyclooctane (DBO) inhibitor?

• Clavulanic acid
• Vaborbactam
• Avibactam
• Sulbactam

Correct Answer: Avibactam

Q4. Which statement is true regarding inhibitors active against metallo‑β‑lactamases (class B)?

• Clavulanic acid reliably inhibits class B MBLs
• Avibactam is a potent inhibitor of NDM and VIM
• There is no widely used commercial inhibitor that effectively inhibits class B MBLs
• Vaborbactam chelates zinc in MBLs and inactivates them

Correct Answer: There is no widely used commercial inhibitor that effectively inhibits class B MBLs

Q5. Which combination contains clavulanic acid as the inhibitor?

• Amoxicillin‑clavulanate
• Piperacillin‑tazobactam
• Ceftazidime‑avibactam
• Meropenem‑vaborbactam

Correct Answer: Amoxicillin‑clavulanate

Q6. Piperacillin is commonly combined with which β‑lactamase inhibitor?

• Tazobactam
• Vaborbactam
• Avibactam
• Clavulanic acid

Correct Answer: Tazobactam

Q7. Ceftazidime‑avibactam is an important combination because avibactam restores activity against which enzymes?

• Metallo‑β‑lactamases (NDM, VIM)
• Class A carbapenemases (KPC) and some class D (OXA‑48) enzymes
• Only narrow‑spectrum penicillinases
• All classes including class B

Correct Answer: Class A carbapenemases (KPC) and some class D (OXA‑48) enzymes

Q8. Vaborbactam is structurally characterized as which type of inhibitor?

• D‑amino acid analog
• Cyclic boronic acid inhibitor
• β‑lactam suicide inhibitor
• Metalloenzyme chelator

Correct Answer: Cyclic boronic acid inhibitor

Q9. Meropenem‑vaborbactam is particularly useful against organisms producing which enzyme?

• Class B metallo‑β‑lactamases (NDM)
• Klebsiella pneumoniae carbapenemase (KPC, a class A carbapenemase)
• Typical community penicillinases only
• Extended‑spectrum OXA‑type MBLs

Correct Answer: Klebsiella pneumoniae carbapenemase (KPC, a class A carbapenemase)

Q10. How does clavulanic acid typically inactivate serine β‑lactamases?

• By reversible noncovalent binding to the active site
• By chelating the active‑site zinc ion
• By forming an irreversible acyl‑enzyme complex (suicide inhibition)
• By degrading the enzyme via proteolysis

Correct Answer: By forming an irreversible acyl‑enzyme complex (suicide inhibition)

Q11. Which inhibitors are known to inhibit KPC carbapenemases?

• Avibactam and vaborbactam
• Clavulanic acid and sulbactam only
• Tazobactam alone
• No inhibitors inhibit KPC

Correct Answer: Avibactam and vaborbactam

Q12. Which of the following best describes avibactam’s interaction with β‑lactamases?

• It is a suicide inhibitor that irreversibly inactivates all enzymes
• It is a reversible covalent DBO inhibitor that can inhibit class A, some class C and some class D enzymes
• It chelates zinc to inhibit metallo‑β‑lactamases
• It non‑specifically disrupts bacterial membranes

Correct Answer: It is a reversible covalent DBO inhibitor that can inhibit class A, some class C and some class D enzymes

Q13. Which inhibitor is most likely to pose cross‑allergy risk in a penicillin‑allergic patient?

• Avibactam (non‑β‑lactam)
• Vaborbactam (boronic acid)
• Clavulanic acid (β‑lactam core)
• Relebactam (DBO)

Correct Answer: Clavulanic acid (β‑lactam core)

Q14. Which combination is primarily indicated for complicated urinary tract infections due to KPC producers?

• Ceftazidime‑avibactam
• Amoxicillin‑clavulanate
• Piperacillin‑tazobactam
• Cefazolin alone

Correct Answer: Ceftazidime‑avibactam

Q15. Which β‑lactamase class is defined as metallo‑β‑lactamases?

• Class A
• Class B
• Class C
• Class D

Correct Answer: Class B

Q16. Which inhibitor has demonstrated activity against many class C (AmpC) β‑lactamases?

• Clavulanic acid only
• Avibactam
• Vaborbactam alone
• Tazobactam exclusively

Correct Answer: Avibactam

Q17. Which of the following resistance mechanisms commonly reduces efficacy of β‑lactam/β‑lactamase‑inhibitor combinations?

• Production of metallo‑β‑lactamases (MBLs)
• Increased permeability to antibiotics
• Inhibition of efflux pumps
• Increased antibiotic activation

Correct Answer: Production of metallo‑β‑lactamases (MBLs)

Q18. The laboratory phenotypic test for ESBL typically demonstrates synergy between a cephalosporin and which inhibitor?

• Vaborbactam
• Clavulanic acid
• Avibactam
• Relebactam

Correct Answer: Clavulanic acid

Q19. Which adverse effect is particularly associated with clavulanic acid when combined with amoxicillin?

• Nephrotoxicity requiring dialysis
• Cholestatic hepatitis and liver enzyme abnormalities
• Severe bone marrow aplasia
• Permanent peripheral neuropathy

Correct Answer: Cholestatic hepatitis and liver enzyme abnormalities

Q20. Which inhibitor is most commonly combined with imipenem to restore activity against some resistant Gram‑negatives?

• Vaborbactam
• Relebactam
• Tazobactam
• Clavulanic acid

Correct Answer: Relebactam

Q21. Why are β‑lactamase inhibitors co‑administered with β‑lactam antibiotics?

• They increase renal clearance of the antibiotic
• They reduce bacterial uptake of the antibiotic
• They inhibit β‑lactamases, preventing hydrolysis of the partner β‑lactam and preserving its activity
• They act as vaccine adjuvants

Correct Answer: They inhibit β‑lactamases, preventing hydrolysis of the partner β‑lactam and preserving its activity

Q22. Which inhibitor class is least effective against OXA‑48‑like carbapenemases?

• Avibactam (has some activity)
• Vaborbactam (limited activity)
• Relebactam (limited activity)
• All are equally effective

Correct Answer: Vaborbactam (limited activity)

Q23. The first clinically used β‑lactamase inhibitor introduced with a penicillin antibiotic was:

• Avibactam with ceftazidime
• Clavulanic acid with amoxicillin
• Vaborbactam with meropenem
• Relebactam with imipenem

Correct Answer: Clavulanic acid with amoxicillin

Q24. Which β‑lactamase inhibitor is a boronic acid derivative designed to inhibit serine carbapenemases?

• Clavulanic acid
• Avibactam
• Vaborbactam
• Sulbactam

Correct Answer: Vaborbactam

Q25. Against which class of enzymes do current clinical β‑lactamase inhibitors generally show minimal or no activity?

• Class A (penicillinases/ESBLs)
• Class B (metallo‑β‑lactamases)
• Class C (AmpC enzymes)
• Some class D (OXA types)

Correct Answer: Class B (metallo‑β‑lactamases)

Q26. Which inhibitor is most likely to restore activity of piperacillin against ESBL‑producing E. coli in vitro?

• Clavulanic acid
• Vaborbactam
• Metronidazole
• Colistin

Correct Answer: Clavulanic acid

Q27. Which clinical syndrome is piperacillin‑tazobactam commonly used to treat?

• Simple streptococcal pharyngitis only
• Complicated intra‑abdominal and hospital‑acquired infections with Gram‑negative coverage
• Viral upper respiratory infections
• Uncomplicated cystitis best treated with nitrofurantoin

Correct Answer: Complicated intra‑abdominal and hospital‑acquired infections with Gram‑negative coverage

Q28. Which phenomenon can reduce inhibitor effectiveness by limiting antibiotic access to target enzymes?

• Increased outer membrane porin expression
• Porin loss or decreased permeability
• Enhanced antibiotic activation
• Decreased efflux pump activity

Correct Answer: Porin loss or decreased permeability

Q29. Which inhibitor has clinical evidence of activity against both class A and class C β‑lactamases, making it useful against some AmpC producers?

• Clavulanic acid only
• Avibactam
• Tazobactam exclusively
• None — AmpC cannot be inhibited clinically

Correct Answer: Avibactam

Q30. Relebactam is combined with which carbapenem in an approved formulation?

• Meropenem
• Imipenem (with cilastatin)
• Ertapenem
• Aztreonam

Correct Answer: Imipenem (with cilastatin)

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com