IN recent years there has been an ever increasing interest in the human enteric flora in normal and pathologic states.1 2 3 4 Current reports have focused on germ-free animals,5 6 7 the effect of suppressing the enteric flora with antibiotics,8 9 10 the relation of intestinal bacteria and leukocytes,6 , 11 the effect of malnutrition on the ecology of the gut12 and the growing recognition of the genus bacteroides as being an important inhabitant of the normal adult colon.5 , 13 Renewed interest in bacterial overgrowth of the small bowel and its association with hematologic syndromes, malabsorptive states and morphologic mucosal changes is again evident.9 , 10 , 14 , 15 Quantitative bacterial change occurring in . . .