Absorbable vs. non-absorbable antibiotics in the treatment of small intestine bacterial overgrowth in patients with blind-loop syndrome

Background: Small intestine bacterial overgrowth is associated with the presence of predisposing conditions, acting through different mechanisms. Therefore, the failure to define a standardized therapy may be due to a methodological bias: to treat a condition characterized by different pathophysiological mechanisms with the same pharmacological approach. Non-absorbable antibiotics could have a lower efficacy than absorbable drugs in patients with blind loops which exclude a portion of the intestine from the transit. Aim: To evaluate the efficacy of absorbable vs. non-absorbable antibiotics in this subgroup of patients. Methods: A group of small intestine bacterial overgrowth patients with total gastrectomy or gastrojejunostomy and blind loop underwent a therapeutic trial comparing rifaximin to metronidazole. Seven patients underwent a course of rifaximin followed by a course of metronidazole on recurrence of symptoms. To compare the effect of the drugs, another two groups of patients underwent two consecutive courses of rifaximin or metronidazole. Hydrogen breath test after glucose administration and symptom severity measurement were performed. Results: Both drugs reduced breath H-2 excretion but a much better improvement was achieved after metronidazole. Symptom improvement was higher after metronidazole. Conclusion: Metronidazole is more effective than rifaximin for the treatment of small intestine bacterial overgrowth associated with the presence of a blind loop.