Mark Pimentel, MD

Director, GI Motility Program

Director, GI Motility Laboratory
Phone:(310) 423-6143
Fax:(310) 423-8356

Academic Appointments

Associate Professor, Medicine

Awards and Activities

Friends of Nurses Award2008
Editorial Board: American Journal of Gastroenterology2006 - 2007
Editorial Board: Gastroenterology and HepatologyCurrent
American College of Gastroenterology1996
Fellow of the Royal College of Physicians of Canada1996
American Gastroenterological Association1999
American Motility Society2000

Research Focus

The study of gut microbes and their relationship to function disorders of the gastrointestinal tract. Specifically, the association between acute gastroenteritis, small intestinal bacterial overgrowth in the pathophysiology of irritable bowel syndrome. The research includes basic science, physiology as well as clinical and translational research.

Research Contributions

Led development of the concept of small intestinal bacterial overgrowth as a potential cause of irritabale bowel syndrome. This has included the discovery that methane producing bacteria in the gut can cause constipation. Demonstrated the efficacy of antibiotics in IBS.

Current investigations include:

Small intestinal bacterial overgrowth in IBS. Acute gastroenteritis models of post-infectious IBS and bacterial overgrowth. The study of gut microbe GI Motility interactions.

Selected Publications

  1. Khoshini R, Dai SC, Lezcano S, Pimentel M: A systematic review of diagnostic tests for small intestinal bacterial overgrowth. Dig. Dis. Sci., 53(6): 1443-54, 2008
  2. Pimentel M, Chatterjee S, Chang C, Low K, Song Y, Liu C, Morales W, Ali L, Lezcano S, Conklin J, Finegold S: A new rat model links two contemporary theories in irritable bowel syndrome. Dig. Dis. Sci., 53(4): 982-9, 2007
  3. Yang J, Lee HR, Low K, Chatterjee S, Pimentel M: Rifaximin versus other antibiotics in the primary treatment and retreatment of bacterial overgrowth in IBS. Dig. Dis. Sci., 53(1): 169-74, 2007
  4. Pimentel M, Lezcano S: Irritable Bowel Syndrome: Bacterial Overgrowth--What's Known and What to Do. Current treatment options in gastroenterology, 10(4): 328-37, 2007
  5. Pimentel M, Chatterjee S, Chow EJ, Park S, Kong Y: Neomycin improves constipation-predominant irritable bowel syndrome in a fashion that is dependent on the presence of methane gas: subanalysis of a double-blind randomized controlled study. Dig. Dis. Sci., 51(8): 1297-301, 2006
  6. Pimentel M, Park S, Mirocha J, Kane SV, Kong Y: The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial. Ann. Intern. Med., 145(8): 557-63, 2006

Lab Information

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