Overview The enterics are Gram-negative bacteria that are part of the normal intestinal flora cause GI disease Classification can be phylogenic or biochemical Phylogenic groups Enterobacteriaceae E. coli Klebsiella pneumoniae Salmonella Shigella Proteus Serratia Vibrionaceae Vibrio cholerae Campylobacter jejuni Helicobacter pylori Pseudomonadaceae Pseudmonas aeruginosa Bacteroidaceae Bacteroides fragilis Biochemical classifications ability to ferment lactose pink on MacConkey agar Citrobacter Klebsiella E. coli Enterobacter Serratia production of H2S