Bacteria in human digestive system, illustration - stock illustration

Bacteria found in human digestive system, computer illustration. Helicobacter pylori (upper right), Enterococcus faecalis (upper left), Lactobacillus spp. (bottom right) and Bifidobacterium spp. (bottom left). Lactobacillus and Bifidobacterium are normal flora and have beneficial functions, such as synthesis of vitamins and protection against pathogens. H. pylori is associated with stomach and duodenal ulcers and gastric cancer. E. faecalis can cause inflammation outside of the intestines, including endocarditis and pyelonephritis.