This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cell Wall Synthesis Inhibitors, Subject name: Pharmacology
Which of the following drug is effective against both Pseudomonas and Proteus? 
Select and explain. 
A. Cloxacillin, B. Amoxicillin, C. Carbenicillin, D. Ampicillin
C: Carbenicillin
Answer: C: Carbenicillin 
Explanation: Carbenicillin is effective against both proteus and pseudomonas. Cloxacillin is a -penicillinase resistant penicillin. - It is mainly effective against gram positive bacteria paicularly those producing penicillinase. - It is not effective against proteus or pseudomonas. Amoxicillin and ampicillin are wide spectrum penicillins. - These are effective against many gram negative bacteria including proteus. However, these are not effective against Pseudomonas. ANTI-PSEUDOMONAL PENICILLINS C: Carbenicillin T: Ticarcillin M: Mezlocillin A: Azlocillin P: Piperacillin