This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Microbial, Subject name: Pharmacology
Which of the following drug acts against Pseudomonas 
Select and explain. 
A. Piperacillin, B. Methicillin, C. Nafcillin, D. Cloxacillin
A: Piperacillin
Answer: A: Piperacillin 
Explanation: Ans. is 'a' i.e., Piperacillin Penicillins effective against PseudomonasPiperacillinMezlocillinTicarcillinCarbenicillinList of other Antipseudomonal have already been given. (May 2003, pharma Q. No. 53)Methicillin, Nafcillin and cloxacillin are penicillinase resistant penicillins