Animal studies have shown that Campylobacter jejuni infection can precipitate an IBS-like condition and that a bacterial toxin called cytolethal distending toxin B (CdtB) might be responsible. If the results of this large study are replicated in other patients with IBS, doctors might have a simple blood test to confirm the diagnosis of D-IBS and to distinguish it from inflammatory bowel disease, celiac sprue and other conditions.