<prompt> All are true regarding resistance of penicillin in staphylococcus aureus, except ?Penicillinase production is transmitted by transductionMethicillin resistance is due to change in PBPHospital strains mostly produce type D penicillinasePenicillinase production is plasmid mediated  <response>: Ans. is c i.e., Hospital strains mostly produce type D penicillinase Resistance to antibiotics a Penicillin resistance is of three types? 1. Production of beta-lactamase penicillinase It inactivates penicillin by splitting 13-lactam ring Its production is controlled by plasmid. Plasmid is transmitted by transduction mainly or conjugation. Penicillinase is an inducible enzyme As a result of the widespread dissemination of plasmids containing penicillinase, less than 5 strains of staph. remain susceptible to penicillin. Staphylococci produce four type of penicillinases, A to D. Hospital strains usually forms type A penicillinase. 2. Changes in bacterial surface receptors by lack or inaccessibility of ceain penicillin binding proteins PBPs in the organism. Methicillin resistant is mainly due to this mechanism and is independent of 3 - lactamase production. It is due to production of PBP 2a. This change in bacterial surface receptors is normally chromosomal in nature. The resistance gene is mec A gene which is a pa of large mobile genetic element - staphylococcal cassette chromosome SCCmec. This genetic material has been transferred to Staph. aureus from S. seiuri. 3. Development of tolerance to penicillin, by which the bacterium is only inhibited but not killed 