Penicillinase resistant penicillin is:
**Core Concept**
Penicillinase-resistant penicillins are a class of antibiotics designed to withstand the action of beta-lactamase enzymes, which are produced by certain bacteria to inactivate penicillin. These enzymes, also known as penicillinases, cleave the beta-lactam ring in penicillin, rendering it inactive.
**Why the Correct Answer is Right**
Penicillinase-resistant penicillins, such as oxacillin and nafcillin, have a modified beta-lactam ring that is resistant to the action of beta-lactamases. This modification is achieved through the addition of a methoxy group or a chloro group to the beta-lactam ring, which prevents the enzyme from cleaving the ring. As a result, these penicillins retain their antibacterial activity against bacteria that produce beta-lactamases.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a penicillinase-resistant penicillin.
**Option B:** This option is not a correct example of a penicillinase-resistant penicillin.
**Option D:** This option is not a penicillinase-resistant penicillin, although it is a type of penicillin.
**Clinical Pearl / High-Yield Fact**
Penicillinase-resistant penicillins are often used to treat infections caused by Staphylococcus aureus, a bacterium that frequently produces beta-lactamases.
**Correct Answer:** C. Oxacillin.