Date of Graduation

7-2015

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor

Dan J. Donoghue

Committee Member

Annie M. Donoghue

Second Committee Member

Michael F. Slavik

Abstract

Campylobacter is the leading cause of foodborne illness worldwide and is often associated with consumption and/or mishandling of contaminated poultry products. Probiotic use in poultry has been an effective strategy in reducing other enteric foodborne pathogens but not consistently for Campylobacter. As Campylobacter resides and utilizes intestinal mucin for growth, isolates selected on the basis of mucin utilization might be a strategy to screen for efficacious probiotic bacterium. In this study, bacterial isolates demonstrating increased growth rates in mucin, in vitro (trials 1 or 2), or isolates demonstrating a reduction of Campylobacter counts when co-incubated with mucin, in vitro (trials 3 or 4) were selected for their ability to reduce Campylobacter colonization in four bird trials. In trials 1 or 2, ninety day-of-hatch chicks were randomly divided into 9 treatment groups (n=10 chicks/treatment) and treated individually with one of four bacterial isolates (Bacillus sp.) demonstrating increased growth in media containing mucin. The treatments included a positive Campylobacter control (no isolate) or four isolates grown in media with or without mucin prior to inoculation. In trials 3 or 4, sixty day-of-hatch chicks were divided into six treatment groups (n=10 chicks/treatment) receiving either no isolate (positive Campylobacter control) or dosed with five individual isolates all demonstrating the ability to reduce Campylobacter counts when co-incubated with mucin, in vitro. These isolates were grown in media containing mucin prior to inoculation. In all four trials, birds were gavaged with individual isolates at day-of-hatch and orally challenged with a four strain mixture C. jejuni on day 7. Ceca were collected at day 14 for Campylobacter enumeration. Results from these first two trials demonstrated two individual isolates, one with increased growth rates when grown in mucin or one isolate when incubated without mucin, consistently reduced cecal Campylobacter counts (1.5 to 4 log reduction) when compared with controls. In follow-up trials with isolates selected for their ability to directly reduce Campylobacter counts when co-incubated with mucin, in vitro, one isolate consistently reduced cecal Campylobacter counts by approximately 1.5 logs. These results support the potential use of mucin to preselect isolates for their ability to reduce enteric Campylobacter colonization.

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