Theses and Dissertations

Kevin Howe

Issuing Body

Mississippi State University

Advisor

Bailey, R. Hartford

Committee Member

Karsi, Attila

Committee Member

Brooks, John P.

Committee Member

Lawrence, Mark L.

Committee Member

Wills, Robert W.

Date of Degree

8-14-2015

Document Type

Dissertation - Open Access

Major

Veterinary Medical Science

Degree Name

Doctor of Philosophy

College

College of Veterinary Medicine

Department

Veterinary Medical Science Program

Abstract

Salmonella can reside in healthy animals without the manifestation of any adverse effects on the carrier. If raw products of animal origin are not handled properly during processing or cooked to a proper temperature during preparation, salmonellosis can occur. In this research, microbial aspects related to Salmonella as a food pathogen are investigated. A bioluminescent reporting system was developed for Salmonella to monitor the attachment and growth of the pathogen on food products. Twelve and eleven Salmonella strains from the broiler production continuum were tagged with bioluminescence by plasmid and integration of the lux operon into the chromosome, respectively. To assess the usefulness of bioluminescent Salmonella strains in food safety studies, an attachment model using chicken skin was developed. Variables including washing and temperature were tested in the attachment model to determine the effects on attachment of Salmonella strains to chicken skin, a characteristic that enhances persistence during processing. Additionally, the invasion process for two serovars of Salmonella with differing host tropism was examined with emphasis on the initial establishment of the bacterium in the host. The major facilitator for invasion, type III secretion system, was inactivated through deletion mutation to evaluate invasion of human epithelial cell line by additional means. The difference in host tropism between the two subspecies of Salmonella was also taken into account when evaluating invasion. Results showed that invasion of human epithelial cells can be initiated despite inactivation of the type III secretion system. A serovar of Salmonella that is not typically associated with human illness was also shown to initiate invasion of human epithelial cells, a result that carries public health implication as this serovar has recently been shown to be multi-drug resistant.

URI

https://hdl.handle.net/11668/21115

Comments

Salmonella||chicken||food pathogen||broiler||bioluminescence||reporter system||invasion||type III secretion system||Typhimurium||Kentucky

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