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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #201855

Title: IDENTIFYING INTESTINAL MICROBIAL POPULATIONS THAT INFLUENCE THE GROWTH OF CAMPYLOBACTER JEJUNI

Author
item RETTEDAL, ELIZABETH - IOWA STATE UNIVERSITY
item Scupham, Alexandra

Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 9/28/2006
Publication Date: 10/20/2006
Citation: Rettedal, E.A., Scupham, A.J. 2006. Identifying intestinal microbial populations that influence the growth of Campylobacter jejuni [abstract]. American Society for Microbiology Meeting. Paper No. 27.

Interpretive Summary: The pathogen Campylobacter jejuni is the most common cause of bacterial-derived food borne illness in the United States, resulting in an estimated 2 million cases annually. Poultry has been recognized as a significant vector for this pathogen into the food supply, with 90% of poultry carcasses contaminated at slaughter. Competitive exclusion (CE), by which nonpathogenic microbiota exclude pathogenic bacteria from the intestinal ecosystem, is a promising intervention strategy for reduction of Campylobacter in poultry products. However identification of microbes with CE capabilities is essential for development of this method. To date, roughly 60% of the poultry intestinal microbiota has been cultured, leaving a diverse undescribed community performing potentially important CE functions. In this work we divided an adult, Campylobacter-free intestinal community into groups by first inoculating the community into day-old turkeys, isolating the birds in groups and then treating each group with therapeutic levels of an antibiotic: Virginiamycin, targeting the ribosomal 50S subunit, Enrofloxacin targeting RNA polymerase, Neomycin targeting the ribosomal 30S subunit, or Vancomycin targeting the cell wall. After a seven day resting period to allow dissipation of the antibiotics, the animals were challenged with 10**4 Campylobacter jejuni. Seven days post challenge all animals were killed and Campylobacter was quantified from the cecal contents. Turkeys treated with Virginiamycin harbored 1X10**9 C. jejuni cfu/g cecal contents while Enrofloxacin, Neomycin, and Vancomycin treated birds harbored 6X10**6, 3X10**5, and <10**3 cfu/g cecal contents, respectively. Untreated controls harbored 2.5X10**7 cfu/g cecal contents. A repeat experiment is planned, and future experiments will use molecular methods to identify the microbes associated with both the Campylobacter-facilitating (Virginiamycin derived) and Campylobacter-inhibiting (Vancomycin derived) functions identified in this work. It is of interest to note that Virginiamycin, an antibiotic commonly used in the poultry industry for growth promotion, facilitated Campylobacter colonization in this work. The impact of this work will be an enhanced understanding of the ecology of Campylobacter in the intestinal ecosystem, which will lead to new intervention strategies for decreasing contamination of poultry products by this food borne pathogen.

Technical Abstract: The pathogen Campylobacter jejuni is the most common cause of bacterial-derived food borne illness in the United States, resulting in an estimated 2 million cases annually. Poultry has been recognized as a significant vector for this pathogen into the food supply, with 90% of poultry carcasses contaminated at slaughter. Competitive exclusion (CE), by which nonpathogenic microbiota exclude pathogenic bacteria from the intestinal ecosystem, is a promising intervention strategy for reduction of Campylobacter in poultry products. Identification of microbes with CE capabilities is essential for development of this method. In this experiment, groups of day-old turkeys (n=4) were orally inoculated with cecal microbiota from a Campylobacter-free adult. Each group was then subjected to treatment with a therapeutic level of a single antibiotic, virginiamycin, enrofloxacin, neomycin, or vancomycin, to select for unique populations present in the initial inoculum. After communities had been selected, the turkeys were challenged with an infectious dose of C. jejuni. Plate counts were performed to quantify the C. jejuni in the ceca. Turkeys treated with virginiamycin harbored 1X10**9 C. jejuni cfu/g cecal contents while enrofloxacin, neomycin, and vancomycin harbored 6X10**6, 3X10**5, and <103 cfu/g cecal contents, respectively. Untreated controls harbored 2.5X10**7 cfu/g cecal contents. Oligonucleotide Fingerprinting of rRNA Genes (OFRG) will be used to describe microbial populations present in each group. Preliminary results indicate that it may be possible to identify populations of microbes that have both the ability to promote and to inhibit growth of the pathogen.