Characterization of Non-O157 STEC Infecting Bacteriophages Isolated from Cattle Faeces in North-West South Africa

Emmanuel W Bumunang,Yan D Niu,Hany Anany,Tim A Mcallister,Collins N Ateba,Kim Stanford

doi:10.3390/microorganisms7120615

Abstract

Non-O157 Shiga toxin-producing Escherichia coli (STEC) E. coli are emerging pathotypes that are frequently associated with diseases in humans around the world. The consequences of these serogroups for public health is a concern given the lack of effective prevention and treatment measures. In this study, ten bacteriophages (phages; SA20RB, SA79RD, SA126VB, SA30RD, SA32RD, SA35RD, SA21RB, SA80RD, SA12KD and SA91KD) isolated from cattle faeces collected in the North-West of South Africa were characterized. Activity of these phages against non-O157 STEC isolates served as hosts for these phages. All of the phages except SA80RD displayed lytic against non-O157 E. coli isolates. Of 22 non-O157 E. coli isolates, 14 were sensitive to 9 of the 10 phages tested. Phage SA35RD was able to lyse 13 isolates representing a diverse group of non-O157 E. coli serotypes including a novel O-antigen Shiga toxigenic (wzx-Onovel5:H19) strain. However, non-O157 E. coli serotypes O76:H34, O99:H9, O129:H23 and O136:H30 were insensitive to all phages. Based on transmission electron microscopy, the non-O157 STEC phages were placed into Myoviridae (n = 5) and Siphoviridae (n = 5). Genome of the phage ranged from 44 to 184.3 kb. All but three phages (SA91KD, SA80RD and SA126VB) were insensitive to EcoRI-HF and HindIII nucleases. This is the first study illustrating that cattle from North-West South Africa harbour phages with lytic potentials that could potentially be exploited for biocontrol against a diverse group of non-O157 STEC isolated from the same region.

Highlights

Non-O157 Shiga toxin-producing Escherichia coli (STEC) are emerging pathotypes that are frequently associated with diseases ranging from diarrhoea to a more complicated haemorrhagic colitis in humans [1]
As well as the recent report of Korf, Meier-Kolthoff, Adriaenssens, Kropinski, Nimtz, Rohde, van Raaij and Wittmann [34], which indicates a diverse group of myoviruses and siphoviruses from various sources such as surface water, manure sewage and animal faeces with lytic capability for different non-O157 E. coli from human origin
The presence of T4 phages (SA79RD, SA35RD, SA20RB and SA21RB) and Jersey-like phages in cattle faecal samples from the North-West South indicate that these phages with lytic activity are good candidates for biocontrol of diverse pathogenic non-O157 E. coli strains

Summary

Introduction

Non-O157 Shiga toxin-producing Escherichia coli (STEC) are emerging pathotypes that are frequently associated with diseases ranging from diarrhoea to a more complicated haemorrhagic colitis in humans [1]. The most common non-O157 STEC are O26, O45, O103, O111, O121 and O145 These serogroups are called the “big six“ because they are often associated with severe illness and death in humans and have been declared as adulterants by the United States Department of Agriculture [2]. The public impact of non-O157 STEC strains on humans is worsened by an overall lack of effective treatment and prevention measures even for those that are susceptible to antimicrobial agents [3]. Against this background, numerous outbreaks of human infections caused by non-O157 STEC strains have been reported globally [4,5]. Effective pathogen control measures in ready to eat products are required especially in case of disease outbreaks

Methods

Discussion

Conclusion