What It Is. A stool (feces) sample can provide doctors with valuable information about what's going on when a child has a problem in the stomach, intestines, or other part of the gastrointestinal (GI) system. A stool culture helps the doctor determine if there's a bacterial infection in the intestines.A technician places small stool samples in sterile plastic dishes containing nutrients that encourage the growth of certain bacteria.hat It Is. A stool (feces) sample can provide doctors with valuable information about what's going on when a child has a problem in the stomach, intestines, or other part of the gastrointestinal (GI) system. A stool culture helps the doctor determine if there's a bacterial infection in the intestines.