The efficacy of oral antimicrobials in reducing aerobic and anaerobic colonic mucosal flora
J. I. Groner, C. E. Edmiston Jr, C. J. Krepel, G. L. Telford and R. E. Condon
Department of Surgery, Medical College of Wisconsin, Milwaukee 53226.
We investigated the impact of intestinal antisepsis on the colonic
mucosa-associated flora. Four groups of dogs were studied: group A received
no bowel preparation, group B received a three-day clear-liquid diet, group
C underwent mechanical cleansing of the bowel, and group D had mechanical
cleansing followed by oral neomycin and erythromycin. Mucosal biopsy
specimens were obtained for bacteriologic and scanning electron microscopic
(SEM) studies. No significant difference in recovery of mucosal bacteria
was observed between groups A and B. A significant decrease in recovery of
aerobes was observed in group C, and a significant decrease in both aerobes
and anaerobes was observed in group D compared with group A;
Enterobacteriaceae and Bacteroides were either eliminated or greatly
reduced. The SEM analysis of group D revealed a marked decrease in
mucosa-associated microflora compared with groups B and C. Oral
neomycin-erythromycin produced a significant quantitative reduction in the
colonic mucosa-associated bacterial population, including the potentially
pathogenic Escherichia coli and Bacteroides fragilis group isolates. These
mucosa-associated bacteria are a likely source of contamination of the
abdominal cavity and wound at the time of colon surgery.
