The present invention relates to an antimicrobial composition for uracil non-secretory (URA−) bacteria, comprising uracil, uracil precursors, uracil analogs, or uracil-secreting opportunistic pathogens as an active ingredient and a composition for preventing cell damage caused by uracil-secretory (URA+) bacteria, comprising ROS scavengers as an active ingredient. The present invention also relates to food or feed for antimicrobial activity and preventing cell damage, comprising said composition a method for controlling dual oxidase (DUOX) activation, the generation of reactive oxygen species (ROS), or the level thereof a method for producing cells, wherein DUOX activation, the generation of ROS, or the level thereof are controlled and a method for providing information on gut pathogenicity in isolated bacteria. The composition of the present invention has effects for preventing symptoms caused by bacteria according to a mechanism which has been unknown in the art. Further, the present invention can be efficiently utilized for establishing prevention and treatment strategies for symptoms caused by bacteria later, as therapeutic strategies can be readily established by bacterial classification based on criteria that can be easily confirmed.
