I had taken anti biotic medicine for pylori some years back. is it possible i am infected again ?

It happens but rare: There is a very low rate of helicobacter pylori recurrence noting these factors: most recur/relapse during the first year which may represent incomplete/ineffective treatment of initial infection. Often, the genetically identical organism is found suggesting a common source of infection even after significant time has passed. So it IS possible...pursue repeat testing if you have recurrent symptoms