Bacterial flora in the alimentary canal of dogs. 1. Normal flora in various parts of the intestinal tract

Abstract

The contents of duodenum, middle part of the small intestine, terminal ileum, andrectum of 13 healthy adult dogs were sampled for qualitative and quantitative studieson bacterial flora. The results obtained are summarized as follows.l) The more backward a portion of the intestine, the higher became the totalviable bacterial count in the portion. The mean of total bacterial count was 7.6 and 9.7, as expressed in log value, in duodenal and rectal contents, respectively.13) Streptococcus, Lactobacillus, and Clostridium were predominant in the duodenalportion. The more backward a portion, the higher became the count of Streptococcus.The count of Streptococcus was characteristic of total viable bacteria. Both Lactobacillusand Clostridium showed a slight increase in count in any portion posterior to theduodenum.3) Enterobacteriaceae tended to increase iut count in the portions posterior to theduodenum up to the terminal ileum. The count of Bacteroides was low in the smallintestine, while it exhibited a sharp increase in the large intestine. Bifidobacteriumtended to increase in count both in the posterior portion of the small intestine and inthe large intestine.4) Staphylococcus and yeasts were found rather infrequently or in relatively Sllllllnumbers. Neither of them was regarded as a resident. Veillonella was not found inany case studied.5) The predominant bacterial groups in tlte rectal content were Streptococcus, Lactobacillus, Bifidobacterium, Clostridium, Enterobacteriaceae, and Bacteroides.6) There were individual variations in count among predominant groups orbacteria found in various portions of the intestine. These variations were especiallydistinct in the anterior portion of the intestinal tract and in the count of Bifidobacterium.7) From the present studies, no definite conclusions could be drawn as to anypossible relationship of count among the predominant groups of bacteria.