Prevention of diarrhea by the probiotic, Lactobacillus GG

Micronutrients (including zinc) reduce diarrhoea in children: the Pakistan Sprinkles Diarrhoea Study

AIMS

To examine the effect of the daily use of micronutrients (including zinc) or the same micronutrients plus heat inactivated lactic acid bacteria (LAB), on diarrhoea in children compared to placebo.

METHODS

A triple blind randomised clinical trial in an urban slum of Karachi, Pakistan. Micronutrients (including zinc), micronutrients (including zinc and LAB), or placebo, were provided daily for two months to 75 young children (aged 6-12 months) identified at high risk for diarrhoea related mortality on the basis of history of at least one episode of diarrhoea in the preceding two weeks. The longitudinal prevalence of diarrhoea was defined as the percentage of days a child had diarrhoea out of the days the child was observed.

RESULTS

Mean longitudinal prevalence of diarrhoea in the micronutrient-zinc group was 15% (SD = 10%) child-days compared to 26% (SD = 20%) child-days in the placebo group and 26% (SD = 19%) child-days in the micronutrient-zinc-LAB group. The difference between the micronutrient-zinc-LAB and placebo groups was not significant.

CONCLUSION

The daily provision of micronutrients (including zinc) reduces the longitudinal prevalence of diarrhoea and thus may also reduce diarrhoea related mortality in young children; heat inactivated LAB has negative effects in these children.

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens

The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

Probiotic use in children

Interest in nutritional supplements and functional foods has risen significantly in recent years. Many of the products that are marketed to consumers tout the benefits of probiotics for general good health and for a wide variety of conditions and situations. Although most of these products have been used safely for years, careful analysis of scientific research should be conducted before routinely recommending these products, especially for children. A basic understanding of intestinal flora, properties of probiotics, and clinical research findings is necessary for clinicians to delineate the role of probiotic agents in the pediatric population.

Acid tolerance and fecal recovery following oral administration of Saccharomyces cerevisiae

Probiotic microorganisms to be used as biotherapeutic agents have to resist the rigors of the upper human gastrointestinal tract. In this study we evaluated the acid tolerance in vitro and the fecal recovery in vivo after oral administration of a Saccharomyces cerevisiae strain to healthy volunteers. At the lowest pH value (pH 1.0) the yeast load in tablets decreased slightly. From pH 1.0 to pH 7.0 the release of S. cerevisiae in buffer solutions increased. The selected yeast strain showed good tolerance to low pH which mimic the gastric environment. After one month of treatment at a dose of 100 million cells per day, S. cerevisiae grew from the feces of 6 (37.5%) of the 16 healthy, treated volunteers. Based on the results of the present experiments the yeast studied can be considered a strain that tolerates adverse conditions comparable to those of the human gastrointestinal tract, and when administered orally may colonize the bowel of healthy volunteers and even replace resident Candida species.

Pre-, pro- and synbiotics

Approximately 70% of the immune system is localized in the gastrointestinal tract. The saliva and gastrointestinal secretions, as well as flora (probiotics) and supplied fibres (prebiotics), are important for optimal function. Probiotic bacteria have been shown to influence the immune system through several molecular mechanisms. Pre-, pro- and synbiotics (products produced by fermentation) offer both protection against and cure of a variety of endemic and acute diseases. This review summarizes the present experience in various forms of diarrhoea, inflammatory bowel disease, and Helicobacter infections, in intensive care patients and in connection with extensive surgery.

Viral causes of diarrhea

Viruses are important causes of diarrhea. In healthy adults, the main clinical manifestation is acute, self-limited gastroenteritis. Advances in molecular diagnostics have shown that epidemics of acute gastroenteritis most frequently are due to caliciviruses spread through contaminated food or through person-to-person contact. Application of similar technology is needed to make a definitive statement about the role of such candidate viruses as rotavirus, astrovirus, and adenovirus as the cause of nonepidemic acute gastroenteritis in adults. Rarely a previously healthy adult gets acute CMV colitis. CMV and EBV mainly cause diarrhea in immunocompromised patients, however. Advances in prophylaxis and treatment have reduced the frequency and severity of these diseases. Acute infantile gastroenteritis is caused by rotavirus, calcivirus, astrovirus, and adenovirus. These viral diseases of the gut are seen by the physician as routine and rare clinical problems.

Probiotic agents and infectious diseases: a modern perspective on a traditional therapy

There is an increasing scientific and commercial interest in the use of beneficial microorganisms, or "probiotics," for the prevention and treatment of disease. The microorganisms most frequently used as probiotic agents are lactic-acid bacteria such as Lactobacillus rhamnosus GG (LGG), which has been extensively studied in recent literature. Multiple mechanisms of action have been postulated, including lactose digestion, production of antimicrobial agents, competition for space or nutrients, and immunomodulation. We have reviewed recent studies of probiotics for the treatment and control of infectious diseases. Studies of pediatric diarrhea show substantial evidence of clinical benefits from probiotic therapy in patients with viral gastroenteritis, and data on LGG treatment for Clostridium difficile diarrhea appear promising. However, data to support use of probiotics for prevention of traveler's diarrhea are more limited. New research suggests potential applications in vaccine development and prevention of sexually transmitted diseases. Further studies are needed to take full advantage of this traditional medical approach and to apply it to the infectious diseases of the new millennium.

Probiotics in pediatric gastrointestinal disorders

Probiotics have been defined most recently as living microorganisms which, upon ingestion in certain numbers, exact health benefits beyond inherent general nutrition. They have been a part of human nutrition for centuries, but in recent years they have been more closely studied for their potential to improve health and treat disease. This review of probiotics is not extensive, highlighting the most recent reviews and well controlled clinical studies in both animals and humans. The safety issues are also discussed as well as potential mechanisms of action. The importance of studying each probiotic bacterium individually in each condition where a health benefit is claimed is highlighted by Lactobacillus GG, the most widely studied probiotic which has proven benefit in reducing the severity and duration of viral diarrhea but no benefit against bacterial diarrhea.

Gastrointestinal infections in children

New pathogens that cause gastroenteritis in children are being recognized. Even well-recognized pathogens, such as Clostridium difficile, may require more extensive testing than was previously thought necessary. Several new tests have emerged that allow for faster identification of these pathogens so that same-day results may be possible. Probiotic therapy has emerged as a novel strategy for the treatment of gastroenteritis. New vaccines against both viral and bacterial causes of gastroenteritis are being developed. The most exciting recent advance in vaccine development may be the creation of edible vaccines.