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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR CHARACTERIZATION OF MICROBIOTA AND ITS RELATIONSHIP TO THE PREVALENCE OF VIRAL AND BACTERIAL ENTERITIS

Location: Diet, Genomics and Immunology Lab

2012 Annual Report


1a.Objectives (from AD-416):
ARS is interested in determining the impact of health-promoting components in foods including those containing probiotic bacteria. A set of preliminary studies done in Medellin and Bogota, Colombia showed a reduction in Bifidobacterium species in children with diarrhea compared to healthy controls. A more complete clinical diagnosis of the etiology of the diarrhea is needed to support feeding selected probiotics that enhance health-promoting microflora in the intestine. The project plan has one objective that directly relates to this agreement: 1)To elucidate the mechanisms used by probiotic bacteria to improve respiratory and intestinal mucosal responses to allergens, and correlate intestinal microflora composition of pigs and humans with biomarkers of allergic and intestinal disease. The COOPERATOR has received approval from the Ethics Committee from Universidad Javeriana and funding through Banco de la Republica to measure differences in intestinal microflora in children with diarrhea compared to healthy controls. Microflora changes will be tracked by real-time PCR using specific probes for the most common bacterial pathogens (E. coli, Salmonella spp., C. difficile) and viral pathogens such as rotavirus and coronaviruses. Both ARS and the Cooperator will evaluate the modulating effect of probiotic bacteria in children.


1b.Approach (from AD-416):
ARS will acquire processed clinical samples from the Cooperator (nucleic acids from fecal samples) to validate previous results found in two independent cohort studies with children. This information will be used by both ARS and the Cooperator to jointly develop new research studies that specifically focus on the evaluation of probiotic intervention to prevent onset of diarrhea.


3.Progress Report:

Intestinal microflora of healthy children and children with clinical diarrhea in a population of children from a tropical highland in Colombia, South America was analyzed by molecular techniques. The prevalence of Lactobacillus and Bifidobacterium species and associated interactions with enteric viral and bacterial pathogens were determined. Children less than 5 years of age from two different locations were evaluated for presence of clinical diarrhea. Fecal DNA, was used to assess the abundance of commensal bacterial species and presence of enteric pathogens compared to clinically healthy children using molecular protocols. The effect of host demographic factors on diarrhea incidence was also analyzed. The composition of the intestinal microbiota was affected by host demographic factors: age, health status, location, and gender. Overall relative abundance of commensal Bifidobacterium species was inversely correlated with incidence of diarrhea, particularly rotavirus, while certain Lactobacillus species were directly correlated with clinical diarrhea regardless of location. Our results suggest that delivery of Bifidobacterium species or a diet rich in bifidogenic components that promote the growth of Bifidobacterium species should be beneficial for the management of diarrhea in at risk children.


Last Modified: 7/30/2014
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