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P2-167 Characterization of Bacteriophage Integrases in Escherichia coli Reveals the Presence of Prophages Originating from the Foodborne Pathogens Salmonella enterica and Shigella flexneri

Monday, July 27, 2015
Exhibit Hall (Oregon Convention Center)
Anna Colavecchio , Department of Food Science and Agricultural Chemistry, Food Safety and Quality Program, McGill University , Montreal , Canada
Yasmin D'Souza , McGill University, Department of Food Science and Agricultural Chemistry, Food Safety and Quality Program , Montreal , Canada
Brigitte Cadieux , McGill University, Department of Food Science and Agricultural Chemistry, Food Safety and Quality Program , Montreal , Canada
Amanda Lo , McGill University , Montreal , Canada
Lawrence Goodridge , Department of Food Science and Agricultural Chemistry, Food Safety and Quality Program, McGill University , Montreal , Canada
Introduction: Temperate phages constitute a main source of genetic diversity associated with the virulence of many foodborne bacterial pathogens, and these phages are known to encode toxins, effector proteins, and adhesion factors, and to favor the dissemination of antibiotic resistance genes and other mobile genetic elements such as pathogenicity islands. Within the Enterobacteriaceae, the integration of prophages into their bacterial hosts is mediated by site-specific tyrosine integrases.

Purpose: The objective of this study was to characterize the types of prophage integrases contained within the fecal indicator bacteria Escherichia coli, as a measure of the presence and diversity of prophages that may disseminate virulence factors.

Methods: One thousand bacterial isolates were obtained from feces of wildlife collected from bovine feedlots in Colorado, USA. Isolates were confirmed as E. coli through cultural methods and biochemical tests. PCR and gel electrophoresis was used to assess phage integrase gene diversity in E. coli, by using degenerate primer sets designed against all known enteric phage tyrosine integrase sequences located in GenBank.

Results: Of 27 E. coli isolates selected for further study, fourteen (51%) were observed to contain at least one tyrosine integrase, three (11%) isolates contained two tyrosine integrases, and three isolates (11%) had three integrases. Further analysis showed that 11 (41%) of the E. coli isolates contained phages originating from Salmonella enterica and Shigella flexneri, with two isolates potentially containing multiple phages originating from Salmonella enterica. Several phages were induced by the antibiotics mitomycin C and streptonigrin.

Significance: This study highlights the diversity of temperate phages in E. coli, and demonstrates that many of these phages originate from enteric foodborne pathogens in which temperate phages are known to transduce toxin and antibiotic resistance genes. The use of tyrosine integrases as a marker for phage diversity in bacterial species of foodborne importance is also significant.

Back to: Poster Session 2 – Laboratory and Detection Methods; Meat, Poultry and Eggs; Dairy and Beverages; Food Law and Regulation; General Microbiology; Modeling and Risk Assessment
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