Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products

Domonkos Sváb,Trinad Chakraborty,Judit Szabó,Linda Falgenhauer,István Tóth,Manfred Rohde

doi:10.3389/fmicb.2018.00202

Abstract

During recent years, interest in the use of bacteriophages as biocontrol agents against foodborne pathogens has increased, particularly for members of the family Enterobacteriaceae, with pathogenic Escherichia coli, Shigella, and Salmonella strains among them. Here, we report the isolation and characterisation of 12 novel T5-like bacteriophages from confiscated food samples. All bacterophages effectively lysed E. coli K-12 strains and were able to infect pathogenic E. coli strains representing enterohaemorrhagic (EHEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), and enteroinvasive (EIEC) pathotypes, Shigella dysenteriae, S. sonnei strains, as well as multidrug-resistant (MDR) E. coli and multiple strains representing different Salmonella enterica serovars. All the bacteriophages exhibited Siphoviridae morphology. Whole genome sequencing of the novel T5-like bacteriophages showed that they represent two distinct groups, with the genome-based grouping correlating to the different host spectra. As these bacteriophages are of food origin, their stability and lack of any virulence genes, as well as their broad and mutually complementary host spectrum makes these new T5-like bacteriophages valuable candidates for use as biocontrol agents against foodborne pathogenic enterobacteria.

Highlights

Several members of the Enterobacteriaceae family are considered significant foodborne pathogens, with enterohemorrhagic Escherichia coli (EHEC) and Shigella strains capable of causing life-threatening disease even at a very small infectious dose
Using E. coli K-12 C600 strain as the host bacterium, we isolated and characterized 12 novel T5-like bacteriophages from independent food samples of various animal origin from around the world These novel bacteriophages represented two subgroups based on their host specificity
While the most effective host of the bacteriophages were K-12 derivative E. coli strains, several strains representing important intestinal pathotypes of E. coli, Shigella, and Salmonella proved susceptible to the bacteriophages

Summary

Introduction

Several members of the Enterobacteriaceae family are considered significant foodborne pathogens, with enterohemorrhagic Escherichia coli (EHEC) and Shigella strains capable of causing life-threatening disease even at a very small infectious dose (reviewed in Croxen et al, 2013; Anderson et al, 2016). Many of these infections are treated with antibiotic therapy, but this is threatened by the increasing occurrence of multidrug-resistant (MDR) strains (reviewed in Szmolka and Nagy, 2013). There have been clinical trials of phage cocktails against diarrheagenic E. coli on human subjects (Sarker et al, 2012, 2016), but these did not yield results regarding the efficacious use of phage cocktails for such infections

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