<prompt> Which of the following is not mechanism for resistance to MRSA -Resistance is chromosomally mediatedProduced mainly by alteration in PBPsMRSA resistance is absolutely beta-lactamase independentIntrinsic resistance is absent  <response>: Option 1, 2 3 mechanisms for which staphylococcus aureus become resistant to methicillin: i Presence of an acquired penicillin binding protein PBP2a ii Modification of normal Intrinsic penicillin binding proteins MRSA is mediated by mecA gene; which is chromosomally coded. iii Hyperproduction of b-lactamase - Rare Option 3 MRSA resistance is not absolutely b-lactamase independent. Resistance may also be produced by hyperproduction of beta-lactamase. Option 4 Intrinsic Resistance: It is the innate ability of a bacterium to resist a class of antibiotics. S. aureus doesnt show any intrinsic resistance. Enterococci show intrinsic resistance to cephalosporins and cotrimoxazole. 