Amoxicillin + clavulanic acid is active against the following organisms EXCEPT :: (A) Methicillin resistant Staph. aureus, (B) Penicillinase producing Staph. aureus, (C) Penicillinase producing N. gonorrhoeae, (D) β-lactamase producing E. coli
Answer is A. Staphylococcus aureus develops resistance to methicillin by acquiring altered penicillin-binding proteins that have low affinity. No Beta-lactam antibiotic is effective against MRSA.
Clavulanic acid is an inhibitor of β-lactamase. It can restore the sensitivity of penicillins against the organisms who have developed penicillinases.