BACTERIA RAPIDLY COLONIZE AND MODULATE HEALING OF GASTRIC-ULCERS IN RATS

The stomach is generally regarded as an environment that is not conduc ive to bacterial colonization. In this study, we examined the possibil ity that this changes significantly when an ulcer has formed and that colonization of ulcers interferes with the normal healing process. Gas tric ulcers were induced by serosal application of acetic acid. The re lationship between ulcer healing and bacterial colonization was examin ed. The effects of antibiotics, induction of Lactobacillus colonizatio n, and selective colonization with an antibiotic resistant strain of E scherichia coli on ulcer healing were examined. Within 6-12 h of their induction, gastric ulcers were colonized by a variety of bacteria, wi th gram-negative bacteria predominating. Suppression of colonization w ith antibiotics resulted in marked acceleration of healing. Induction of Lactobacillus colonization also accelerated ulcer healing. The bene ficial effects of antibiotics were reversed through selective coloniza tion with antibiotic-resistant E. coli. Bacterial colonization occurre d irrespective of the method used to induce the ulcer. This study demo nstrates that colonization of gastric ulcers in rats occurs rapidly an d significantly impairs ulcer healing. This effect appeared to be prim arily attributable to gramnegative bacteria.