This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Staphylococci, Subject name: Microbiology
How does staph aureus become resistant to methicillin: 
Select and explain. 
A. Heat shock protein, B. Protein A, C. Transpeptidase, D. Protein C
C: Transpeptidase
Answer: C: Transpeptidase 
Explanation: Ans. (c) TranspeptidaseRef: Microbiology by Ananthanarayan and Paniker 8th ed. /197, 201-202Resistance develops due to alteration in transpeptidase (penicillin binding protein) on which all beta lactam antibiotics act- so MRSA is resistant to all b-lactam antibiotics.