|Rettedal, Elizabeth -|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 11, 2010
Publication Date: December 15, 2010
Citation: Scupham, A.J., Jones, J., Rettedal, E.A., Weber, T.E. 2010. Antibiotic Manipulation of Intestinal Microbiota to Identify Microbes Associated with Campylobacter Exclusion in Poultry. Applied and Environmental Microbiology. 76(24):8026-8032. Interpretive Summary: Competitive exclusion (CE) is the process by which native, established organisms in an environment exclude an invading species. Much evidence suggests that this process protects the poultry intestine from colonization by human pathogens, including Campylobacter, the primary bacterial cause of food-borne illness in the United States. Currently the identities of bacteria involved in Campylobacter CE, and thus the CE mechanisms, have not been determined. As poultry consumption is the primary risk factor for development of campylobacteriosis, a need exists to enhance the natural CE ability of the poultry intestinal microbiota. In the current work a method for identification of Campylobacter exclusionary bacteria is presented, along with evidence suggesting that the presence of the bacteria Megamonas hypermegale correlates with Campylobacter CE. To obtain this result, intestinal contents from a Campylobacter-free turkey were inoculated into day-old turkey poults. The poults were then divided into treatment groups and each group was given a different antibiotic to create subsets of the intestinal microbiota. Two weeks later the poults were challenged with Campylobacter. The different antibiotic-derived intestinal microbiota showed treatment-specific levels of CE ability. Of particular interest, the vancomycin-derived microbiota suppressed Campylobacter colonization 58,000-fold compared to the control treatment. Comparison of the antibiotic-derived microbiota identified Megamonas hypermegale as specific to the Campylobacter suppressive treatments. The presented method is a general protocol for examination of the functional abilities of microbial communities, and was initially used to identify a biocontrol agent for root-knot nematode in agricultural fields (Yin et al. 2004. Plant and Soil 259: 19-27). Examination of Campylobacter CE by this method facilitates an understanding of CE mechanisms and the development of alternatives to antibiotic use for promotion of both animal and human health.
Technical Abstract: The ability of various subsets of poultry intestinal microbiota to protect turkeys from colonization by Campylobacter was investigated. Community subsets were generated in vivo by inoculation of day-old poults with the cecal contents of a Campylobacter-free adult turkey, followed by treatment with the antimicrobials virginiamycin, enrofloxacin, neomycin or vancomycin. The enrofloxacin-, neomycin- and vancomycin-derived communities decreased Campylobacter load to varying degrees, with the vancomycin-derived community causing the greatest reduction. Examination of the constituents of the derived communities, via the array-based method oligonucleotide fingerprinting of rRNA genes, detected a subtype of Megamonas hypermegale specific to the Campylobacter-suppressive treatments.