<prompt> A diabetic patient developed cellulitis due to S. aureus, which was found to be methicillin resistant on the antibiotic sensitivity testing. All of the following antibiotics will be appropriate except ?VancomycinImipenemTeicoplaninLinezolid  <response>: Ans. is b i.e., ImipenemMethicillin - resistant staphylococcus - aureus MRSA. Most staphylococci are penicillin resistant because they secrete penicillinase.. To overcome this resistance, penicillinase resistant penicillins, e.g. methicillin and nafcillin were developed.. MRSA is a strain of staphylococcus aureus that has acquired multi-drug resistance - even against methicillin and nafcillin penicillinase resistant penicillin.Treatment of S. aureus infections. Sensitive to penicillin -- Penicillin G is the DOC.. Pt. with penicillin allergy -- Cefazoline is the DOC.MRSA --- Vancomycin is the DOC.Methicillin - resistant staphylococcus - aureus MRSA. Most staphylococci are penicillin resistant because they secrete penicillinase.. To overcome this resistance, penicillinase resistant penicillins, e.g. methicillin and nafcillin were developed.. MRSA is a strain of staphylococcus aureus that has acquired multi-drug resistance - even against methicillin and nafcillin penicillinase resistant penicillin.Treatment of S. aureus infections. Sensitive to penicillin -- Penicillin G is the DOC.. Pt. with penicillin allergy -- Cefazoline is the DOC.. MRSA --- Vancomycin is the DOC.. Other drugs for MRSA are- TMP - SMX - Levofloxacin - Linezolid -Tigecyclin- Minocyclin - Quinopristin - Daptomycin - Teicoplanin KDT - 691- Ciprofloxacin - Dalfopristin - Oritavancin. Adjunctive drugs those that should be used only in combination with other antimicrobial agents for M.R.S.A. are gentamycin, rifampin, fusidic acid.The carbapenem imipenem has excellent activity against methicillin - senstive S. aureus but not M.R.S.A. 