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
Which of the following drug should not be used to treat Klebisella infection? 
Select and explain. 
A. Ampicillin, B. Amikacin, C. Imipenem, D. Tigecycline
A: Ampicillin
Answer: A: Ampicillin 
Explanation: Ans. is 'a' i.e. Ampicillin Treatment of Klebsiella infection o Klebsiella pneumoniae and K.oxytoca are intrinsically resistant to ampicillin and ticarcillin, and nitrofurantoin is only poorly active against them. o Empirical treatment of serious or health care-associated Klebsiella infections include amikacin, or Carbapenem (Imipenem). (According to 17th/e of Harrison, Tigecyclin was also used as empirical treatment). o Treatment of infections due to strain that possess carbapenemases includes Tigecyclin, Polymyxin B, and poly? myxin E (Colistin) (This information has been added in 18th/e of Harrison)