Probiotics: Has enthusiasm outpaced the evidence?

As a Internal Medicine clinician I see a large portion of patients who present with acute onset diarrhea.  Viral etiologies are the most likely cause accounting for nearly 90% .  Other causes include antibiotic associated diarrhea, known as Clostridium Dificille (C. diff) or pseudomembranous colitis, because of the way the bacteria create a layer (membrane) along the colonic border.  Less comon causes could be contributed to toxin mediated (food poisoning) and others could be from Hepatitis A, E coli and or travelers diarrhea.  Giarida (from drinking the water in Mexico) is something we always ask about especially here in Tucson, Arizona. 

I have been asked before, and have thought about the use of Probiotics as an adjunctive treatment for acute diarrhea.  Is there good evidence to support there use? Are there any negative consequences as you are introducing bacteria and live cultures to the "normal" gut flora.  I decided to investigate.  Below are some quotations from various studies.  See for yourself and decide.  I will end with a brief discussion and reccomendation. 

1.  2010 Nov 10;(11):CD003048. Cocharane databse systematic review. 

Probiotics for treating acute infectious diarrhea: 

This was a review of 63 studies from a medical journal database search. 
No adverse events were reported.  They concluded that probiotics decreased the duration of diarrhea although the size of the effect varied considerably between studies.

"Used alongside rehydration therapy, probiotics appear to be safe and have clear beneficial effects in shortening the duration and reducing stool frequency in acute infectious diarrhoea. However, more research is needed to guide the use of particular probiotic regimens in specific patient groups."

2.  J Clin Gastroenterol. 2011 May 5.

A Randomized, Double-blind, Placebo-controlled Pilot Study of Lactobacillus reuteri ATCC 55730 for the Prevention of Antibiotic-associated Diarrhea in Hospitalized Adults.

This is a study just published last week where they conducted a double blinded placebo controlled initiative on patients who were recieving antibiotic therapy.  The end point was diarrhea from any cause. 
"Thirteen patients received L. reuteri and 10 received placebo. Patients treated with L. reuteri had a significantly lower frequency of diarrhea compared with placebo 50% in the placebo group vs. 7.7% in the probiotic group, P=0.02"

CONCLUSIONS:

"In this placebo-controlled, pilot study, L. reuteri twice daily for 4 weeks significantly decreased AAD among hospitalized adults. L. reuteri was safe and well tolerated."

3.  J Nutr Health Aging. 2011 Mar;15(3):215-20.

Probiotics improve bowel movements in hospitalized elderly patients--the PROAGE study.

Daily probiotics were given to elderly patients in Geriatric Orthopedic Rehabilitation Department for 45 days. 
"Throughout the 45 days of follow-up, the incidence of diarrhea was significantly lower among the study group (HR=0.42, p=0.04) with a more pronounced difference among participants aged ≥ 80 y (HR=0.32, p=0.026). "

CONCLUSION:

"We showed that probiotic supplements may have a positive effect on bowel movements among orthopedic rehabilitation elderly patients."

Lastly after reading UpToDate (an evidence based, peer reviewed information resource) they quote the following:  "It is reasonable to recommend probiotics to adults and children with presumed infectious diarrheal illness with the hope of reducing the duration of symptoms by 17 to 30 hours."

Discussion:
Given the smattering of evidence as indicated above and the safety of probiotic regimens,  I believe in acute infections diarrea, it is reasonable to administer lactobacillus within the first 48 hours of symptoms.  There is no FDA approved treatment or amount.  Until there are more definitive double blinded multicenter placebo controlled studies in specific patient populations and at specific doses we cannot reccomend more broad usage of these promising treatments.