<prompt> Which is the drug to treat NARST Nalidixic acid resistant S.typhi?ChloramphenicolAzithromycinCiprofloxacinSeptran  <response>: Nalidixic acid-resistance S.typhi NARST: Surrogate marker of decreased susceptibility to ciprofloxacin. Rx : Azithromycin , third-generation cephalosporins. Aztreonam and Imipenem are the potential second line drugs. 