This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
A diabetic patient developed cellulitis due to staphylococcus aureus, which was found to be Methicillin resistant on the antibiotic sensitivity testing. All the following antibiotics will be appropriate except- 
Select and explain. 
A. Vancomycin, B. Imipenem, C. Teichoplanin, D. Linezolid
B: Imipenem
Answer: B: Imipenem 
Explanation: Ans. is 'b' i.e., Imipenem "The carbapenem imipenem has excellent activity against methicillin-sensitive S.aureus but not MRSA." MRSA is resistant to all beta-lactam antibiotics because resistance develops due to alteration in transpeptidase (penicillin binding protein) on which all beta-lactam antibiotics act. Drugs for MRSA --> Vancomycin (DOC), Ciprofloxacin Quinopristin/dalfopristin Tigecyclin TMP-SMX Linezolid Daptomycin Teicoplanin Minocyclin Levofloxacin Oritavaccin Cotrimoxazole