The normal microbial flora

Summary In a qualitative and quantitative study of bacteria, the mid small intestine and colon of rabbits and dogs, and the upper jejunum and terminal ileum of surgical patients were sampled at laparotomy.The small intestine of rabbits, dogs, and humans was not sterile. The bacterial groups found most frequently were also those present in the greatest numbers. In rabbits and dogs the small intestine contained varied and quantitatively large flora. In man, the small intestine contained only slight median numbers of coliforms and streptococci. These findings support the view that the small intestine of man contains sparse, transient, bacterial flora.Presented at a postgraduate course, Advances in Gastroenterology—Enterocolonic Disease and Dysfunction (Oct. 22–24, 1964) , sponsored by Louisiana State University School of Medicine, New Orleans, La.Supported in part by Grants Al 00524 and Al 01600 from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, U. S. Public Health Service.