This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Drug not affecting pseudomonas aeruginosa ? 
Select and explain. 
A. Levofloxacin, B. Ampicillin, C. Norfloxacin, D. Ciprofloxacin
B: Ampicillin
Answer: B: Ampicillin 
Explanation: Ans. is 'b' i.e., Ampicillin Drugs acting against Pseudomonas. Penicillins - Piperacillin, Carbenicillin, Ticarcillin, Mezlocillin. Cephalosporins - Ceftazidime, Cefoperazone, Cefepime. Carbapenems - lmipenem, meropenem Monobactams - Aztreonam. Aminoglycosides - Tobramycin, Gentamycin, Amikacin. Fluroquinolones - Ciprofloxacin, Levofloxacin, Norfloxacin. Other - Polymixin B, Colistin. For most of the infection of pseudomonas, treatment of choice is the combination of an antipseudomonal plactam and an aminoglycoside.