Mucosal flora of the small intestine and the effect of preoperative antibiotics.

Samples of mucosa from the small intestines of 100 patients undergoing intestinal surgery were examined bacteriologically. Sixty four patients had received chemotherapy, 12 for more than 24 h before operation. Most of the jejunal samples were sterile unless there was a carcinoma, previous surgery, or potential intestinal stasis. Ileal mucosa was more likely to contain intestinal organisms. Most of the strains isolated were sensitive in vitro to the antibiotics given in vivo, but short term treatment may not have allowed sufficient time for the treatment to have become effective. The findings suggest that antibiotics are not needed for most operations on the duodenum or jejunum but may be required for operations on the ileum.