Irritable Bowel Linked To Gut Bacteria, Definitively

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Irritable Bowel Linked To Gut Bacteria, Definitively

Catharine Paddock PhD

Copyright: Medical News Today

A new study of Greek patients shows that overgrowth of bacteria in the

gut is definitively linked to irritable bowel syndrome (IBS). It is

the first to use the " gold standard " method of examining gut bacterial

cultures to connect bacteria to the cause of a disease that affects

some 30 million Americans. The researchers say their findings confirm

antibiotics are a successful treatment for IBS.

Previous studies have suggested a link between gut bacteria and IBS,

but they have been based on testing methane (a byproduct of bacterial

fermentation) in the breath.

The findings, published in the May issue of Digestive Diseases and

Sciences, corroborate those of previous clinical trials at

Cedars-Sinai that showed antibiotics are effective against IBS.

Study author Mark Pimentel is director of the Cedars-Sinai GI Motility

Program. He commented in a statement to the press released on Friday

that:

" While we found compelling evidence in the past that bacterial

overgrowth is a contributing cause of IBS, making this link through

bacterial cultures is the gold standard of diagnosis. "

" This clear evidence of the role bacteria play in the disease

underscores our clinical trial findings, which show that antibiotics

are a successful treatment for IBS, " he added.

For the study, Pimentel and colleagues from Sismanogleion General

Hospital in Athens, Greece, and from the University of Athens,

examined samples of small bowel cultures from over 320 Greek patients

to confirm the presence of small intestinal bacterial overgrowth

(SIBO). The patients were all scheduled to receive upper

gastrointestinal (GI) tract endoscopy.

They found that more than a third of the patients with IBS had SIBO,

compared with only 10% of those without IBS.

Of patients with diarrhea-predominant form of IBS, 60% had SIBO,

compared to just over 27% without the diarrhea form.

The researchers used the Rome II criteria to define IBS. The Rome

criteria is a system, based on clinical symptoms, of classifying

disorders of the digestive system in which symptoms can't be explained

through presence of tissue abnormality. As well as IBS, other

disorders that are defined using Rome criteria include dyspepsia,

functional constipation, and functional heartburn.

Pimentel and colleagues conclude:

" Using culture of the small bowel, SIBO by aerobe bacteria is

independently linked with IBS. These results reinforce results of

clinical trials evidencing a therapeutic role of non-absorbable

antibiotics for the management of IBS symptoms. "

IBS is the most common gastrointestinal disorder in the US. Symptoms

include painful bloating, constipation, diarrhea or an alternating

pattern of both.

Many people with IBS avoid social interactions because they are

embarassed by their symptoms.

Ten years ago Pimentel went against the thinking of the time when he

proposed bacteria played a key role in IBS. Since then he has led

clinical trials that have shown rifaximin, a targeted antibiotic

absorbed only in the gut, is an effective treatment for IBS.

Pimentel said in the past, treatments have focused on alleviating

symptoms. But " patients who take rifaximin experience relief of their

symptoms even after they stop taking the medication " .

" This new study confirms what our findings with the antibiotic and our

previous studies always led us to believe: bacteria are key

contributors to the cause of IBS, " he affirmed.

" The Prevalence of Overgrowth by Aerobic Bacteria in the Small

Intestine by Small Bowel Culture: Relationship with Irritable Bowel

Syndrome " ; Emmannouil Pyleris, Evangelos J. Giamarellos-Bourboulis,

Dimitrios Tzivras, Vassilios Koussoulas, Charalambos Barbatzas and

Mark Pimentel; Digestive Diseases and Sciences, Volume 57, Number 5

(2012), 1321-1329; DOI: 10.1007/s10-7; Link to Abstract.

Additional source: Cedars-Sinai Medical Center