Now Cedars-Sinai researchers, have come up with an interesting finding, i.e., rifaximin (see structure)  is the first drug treatment for IBS that relieves symptoms  while it's being administered and continues to benefit patients after  they stop taking the drug. 
Researchers lead by Dr. Mark Pimentel found that patients who took rifaximin not only experienced  relief of their IBS symptoms, including specific symptoms of bloating,  abdominal pain and stool consistency, while they were taking the  antibiotic, but also that their relief was sustained over the 10 week  follow-up period when no antibiotic was administered. 
The results of the studies were presented at the Digestive Disease Week  conference in New Orleans on 3rd May. 
Ref : http://www.cedars-sinai.edu/About-Us/News/Past-Issue-Documents/IBSPimentelACG.pdf"These studies validate the role of altered gut bacteria in IBS," said Dr. Mark Pimentel, GI Motility Program director at Cedars-Sinai and the principal investigator of the clinical trail at Cedars. "These findings show that targeted antibiotics provide safe and long-lasting improvement for IBS patients."........
