system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Select the antimicrobial drug which is used orally only for urinary tract infection or for bacterial diarrhoeas
assistant
The correct answer is  QUINOLONES Nalidixic acid It is active against gram-negative bacteria, especially coliforms: E. coli, Proteus, Klebsiella, Enterobacter, Shigella but not Pseudomonas. mech of action:- It acts by inhibiting bacterial DNA gyrase and is bactericidal. Use s:- 1. Nalidixic acid is primarily used as a urinary antiseptic. 2. It has also been employed in diarrhoea caused by Proteus, E. coli, Shigella or Salmonella, but norfloxacin/ciproloxacin are more commonly used now. Ref:- kd tripathi; pg num:-709