Which of the following is not mechanism for resistance to MRSA?
Ans. is 'c' i.e., MRSA resistance is absolutely beta-lactamase independentMechanism of Resistance of MRSA* There are three known mechanisms for which staphylococcus aureus become resistant to methicillin:(i) Presence of an acquired penicillin binding protein (PBP2a,) Most cases.(ii) Modification of normal (Intrinsic) penicillin binding proteins.(iii) Hyperproduction of b-lactamase - Rare.* S. aureus strains have four intrinsic penicillin binding proteins (PBPs) which have high affinity for b-lactam antibiotics.* PBP2a is an inducible acquired protein that is produced only by MRSA. It is not an intrinsic PBP.* PBP2a has very low affinity for b-lactam antibiotics - staph, aureus strains containing PBP2a, i.e., MRSA are resistant to all b-lactam antibiotics.* Production of PB2a is by chromosomally coded mec A gene which alters PBP to PBP-2a.* Drug resistance can be transferred between S. aureus strain by Transduction.About the other options:* Resistance to MRSA is chromosomally mediated and involves production of an altered penicillin-binding protein (PBP2a).* MRSA resistance is not absolutely b-lactamase independent. Though altered penicillin binding protein is involved in most strains, b-lactamase production is also involved, rarely.
Resistance is chromosomally mediated
Produced mainly by alteration in PBPs
MRSA resistance is absolutely beta-lactamase independent
Intrinsic resistance is known
Bacteria