Sandra Yin

November 08, 2011

November 8, 2011 (National Harbor/Washington, DC) — Mounting evidence is building a strong case for the use of  probiotics, or "good" bacteria, to alleviate common gastrointestinal (GI) symptoms, such as diarrhea, bloating, and inflammation, according to several studies highlighted during a press briefing here at the American College of Gastroenterology 2011 Annual Scientific Meeting and Postgraduate Course.

In one meta-analysis, researchers from the Maimonides Medical Center in Brooklyn, New York, found that in 22 studies of more than 3000 patients, probiotic prophylaxis significantly reduced the odds of developing antibiotic-associated diarrhea and Clostridium difficile–associated diarrhea by about 60%.

In another meta-analysis, researchers from Beth Israel Deaconess Medical Center and Harvard Medical School, in Boston, Massachusetts, analyzed 28 randomized controlled trials in which more than 3000 patients received a single or a combination of antibiotics for various indications. In adult and pediatric populations, the preventive effect of probiotic use was significant, regardless of the species used and regardless of the antibiotic administered.

In the largest study to date on probiotics in a nonpatient population, researchers from the University of North Carolina at Chapel Hill evaluated the efficacy of Bifidobacterium infantis 35624, a probiotic that has relieved symptoms in patients with irritable bowel syndrome, to see how well it relieved abdominal discomfort and bloating in nonpatients.

The double-blind randomized placebo controlled study involved a 2-week placebo phase followed by a 4-week intervention phase, and was conducted at 10 clinical centers in the United States. More than 300 nonpatients who had experienced abdominal discomfort and bloating more than twice weekly, on average, for at least 3 months were included in  the study. They had not seen a physician or received prescribed medication for their symptoms in the previous 12 months.

In contrast to previous clinical studies of irritable bowel syndrome patients, the researchers saw no statistically significant improvement in mean severity of abdominal discomfort or bloating after the nonpatient population took B infantis 35624.

However, an Irish group found that a nonpatient population receiving B infantis 35624 experienced significantly more bloat-free days.

The researchers hypothesized that microbial imbalance could explain the increased incidence of a wide range of inflammatory disorders. To test whether altering the balance between good and bad bacteria in the gut raises the immune regulatory response, which could lower inflammation, researchers from the Alimentary Pharmabiotic Centre at University College Cork, and Alimentary Health Ltd in Cork, Ireland, conducted a double-blind placebo controlled study. Their goal was to see if B infantis affects systemic proinflammatory biomarkers in patients with inflammatory disease.

The results of their study suggest that probiotics exert antiinflammatory effects.

"By giving a specific probiotic orally, we could actually reduce the levels of these proinflammatory cytokines and actually enhance the production of an anti-inflammatory cytokine, which is the exact replication of what we identified in animal models and more basic models," said principal investigator Eamonn Quigley, MD, FACG, professor of medicine at the National University of Ireland in Cork.

Plasma levels of the anti-inflammatory cytokine interleukin (IL)-10 rose significantly in healthy volunteers and patients with psoriasis, but not in those who took the placebo for 8 weeks.

Plasma levels of 2 proinflammatory cytokines — tumor necrosis factor-alpha and IL-6 — dropped in all patients who received B infantis. C-reactive protein levels were also significantly lower in patients with psoriasis, ulcerative colitis, and chronic fatigue after treatment with the bacterium than after treatment with placebo.

Although not everybody who takes an antibiotic should also take a probiotic, the institutionalized elderly should, to minimize the chance of getting something like antibiotic-associated diarrhea or antibiotic-associated C difficile, said Fergus Shanahan, MD, FACG, a researcher involved in the Irish B infantis 35624 study, and professor and chair of the Department of Medicine at University College Cork.

Certain subsets of patients, such as those with cystic fibrosis or chronic urinary infections, who must take recurring courses of antibiotics might benefit from taking probiotics to minimize antibiotic-associated diarrhea.

"It's ironic that we would worry about taking an organism when we've got billions of organisms in the GI tract" and the amount is relatively small, Dr. Shanahan observed. Instead of worrying about drug toxicity in that population, "we're worried about something that has vanishingly low side effects. It can't be zero, but it is very, very low."

"If we paid more attention to prescribing antibiotics, we wouldn't have a lot of these problems," added Dr. Quigley.

According to Mark Mellow, MD, FACG, director of the Digestive Health Center at INTEGRIS Baptist Medical Center in Oklahoma City, Oklahoma, physicians aren't the only ones to blame for the indiscriminate use of antibiotics. Edicts from hospital compliance committees often establish rules that patients who come in with community-acquired pneumonia be placed on antibiotics soon after admission. These rules can have unintended consequences.

"Someone comes in with a fever and a cough and because there's not enough time to sort it out, they get put on an antibiotic," he said, whether or not they have a bacterial infection.

Dr. Quigley reports financial relationships with Alimentary Health, Norgine, Merck, Procter and Gamble, Movetis/Shire, Shire, Yakult, and Ironwood/Almirall. Dr. Shanahan reports a financial relationship with Alimentary Health Ltd. Dr. Mellow has disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2011 Annual Scientific Meeting and Postgraduate Course: Abstracts P650, P120, P60, P283. Presented November 1, 2011.

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