Date

2022-6-03

Author

Güzel, Mustafa

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Antibiotic resistance of pathogenic microorganisms is a severe public health problem. One of the main reasons of the resistance is the overuse of antibiotics in veterinary and food animals. Non-typhoidal Salmonella is a major foodborne pathogen that causes millions of cases each year, worldwide. Although Salmonella causes outbreaks in almost all food commodities, it is mostly associated with poultry. In addition to high prevalence in poultry, Salmonella isolates recovered from poultry have shown multi drug resistance. Use of bacteriophages (phages) has been emerged as a viable alternative for biocontrol of Salmonella. Phages are bacterial viruses that have narrow host range, and are unable to infect eukaryotic cells. They could be utilized for different applications from medicine to food safety. In this study, the main purpose was to isolate and characterize bacteriophages that can be used against multidrug resistant Salmonella serotypes in cattle and poultry farms. 57 samples were collected from poultry farms, cattle farms, and wastewater facility, in 11-month span. From the samples, 12 Salmonella and 68 phages were isolated. Antibiotic resistance profiles of Salmonella isolates were characterized. 66% of Salmonella isolates were multidrug resistant. Genomic clustering and serotypes were determined by pulsed field gen electrophoresis (PFGE). Most abundant phages were Enteritidis phages. Isolated phages purified and stored. Lytic profiles of phages against various hosts were determined. Most of the phages showed broad host range. Based on the host range most potent phages were determined, and phenotypic (host-range, one-step growth, latent period, burst size, adsorption rate, transmission electron microscopy (TEM)) and genomic (PFGE, genome sequencing) features were characterized. Dynamic interaction between phages and hosts were investigated with bacterial reduction curves and virulence index. Enteritidis phages inhibited bacterial growth even at low concentrations. Effectiveness of several phages were tested against their hosts in in vitro feed model. Enteritidis phage significantly reduced host population in feed. In conclusion, a fundamental basis was prepared for a potential phage product.

Subject Keywords

Salmonella, Bacteriophage, Genomics, Food Safety

URI

https://hdl.handle.net/11511/98118

Collections

Graduate School of Natural and Applied Sciences, Thesis