Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Hargis, Billy M.

Committee Member

Tellez, Guillermo

Second Committee Member

Graham, Danielle

Third Committee Member

Latorre Cardenas, Juan D.

Fourth Committee Member

Moore, Randle

Keywords

Koch's postulates; Sepsis; Turkey

Abstract

Streptococcus gallolyticus (SG) is a Gram-positive found as commensal gut flora in animals and humans. SG has been associated with acute mortality in poults 2 to 3 weeks of age, with lesions mainly consisting of splenomegaly, hepatomegaly, and pericarditis. The objective of this thesis was to reproduce disease in poults caused by SG recovered from clinical field isolates and evaluate different routes of administration. Three field isolates from geographically disparate areas in Arkansas and Missouri were used for the experiments contained in this thesis. Antibiotic sensitives of the three field isolates revealed sensitivity to penicillin as well as a wide panel of antibiotics. The three isolates had similar antibiotic sensitivities with the exception of SG2 and SG3 being intermediate for neomycin. All samples tested were intermediate for Sulfamethoxazole/trimethoprim. Penicillin is widely used to treat Gram-positive bacteria such as S. gallolyticus, which have a thick layer of peptidoglycan, by inhibiting the production of peptidoglycan. However, in antibiotic free flocks, growers do not have the luxury of treating with antibiotics, therefore higher mortality has been reported and managing outbreaks may be difficult. Learning more about this bacterium, as well as finding alternatives to antibiotics for SG may lead to clues on how to combat this novel pathogen. Chapter 1 consists of a brief summary of this thesis. Chapter 2 consists of a brief literature review about S. gallolyticus consisting of its relevance, pathogenicity, antibiotic resistance potential, and diagnostics involved in identification of SG. Chapter 3 consists of research conducted, which includes preliminary work, to recreate disease in poults due to challenge from different SG isolates.

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