All of the following are true about Methicillin Resistance in MRSA, EXCEPT:
Multi drug-resistant Staphylococcus aureus (MRSA) becomes resistant to Methicillin due to the alteration in the Penicillin Binding Proteins (PBP-2A) which carries out the functions of PBP's which are inactivated by Methcillin. This is transmitted the MeC A gene. Which is a chromosomal gene (and not a plasmid). Borderline resistance to methicillin may be produced due to hyper production of Beta Lactamases and low resistance to MRSA (hetero resistance) may be missed at 37degC and temperature of incubation no higher than 35degC is recommended but however these are not the primary cause. Ref: Methicillin-Resistant Staphylococcus Aureus (MRSA) Protocols By Yinduo Ji, Volume 391; Lippincott's Illustrated Reviews: Pharmacology, 4th Edition, Page 326
Resistance is produced as a result of altered PBP's
Resistance may be produced by hyper production of Beta Lactamase
Resistance is primarily mediated /transmitted plasmids
Resistance may be missed at incubation temperature of 37degC during susceptibility testing