Types and distribution of anaerobic bacteria in the large intestine of pigs.

An examination was made of various sites along the length of the swine large intestine, using strictly anaerobic culture methods. Sites were separated by differential washing into fractions described as lumenal content, lumenal surface layer, and intestinal wall tissue. Direct microscopic clump counts averaged 13.3 x 10 organisms per g (dry weight) of material in the lumenal content, 14.0 x 10 in the surface layer, and 5.1 x 10 in the intestinal wall tissue. Both direct microscopic counts and viable culture counts were higher from the lumenal content and surface layer than from the intestinal tissue at all sites sampled in the intestine. Cultural counts averaged 56.2% of the direct microscopic counts in lumenal content and surface layer and 20.2% in intestinal tissue. Over 90% of the bacteria isolated were gram positive and consisted mainly of gram-positive cocci, lactobacilli, eubacteria, and clostridia. Of 192 isolates recovered, only 124 could be assigned to recognized species.