In Vitro Evaluation of a Phage Cocktail Controlling Infections with Escherichia coli.

Imke H E Korf,Christine Rohde,Sophie Kittler,Tatiana Lehnherr,Ruth Mengden,Hansjörg Lehnherr,Antje Flieger,Andrea Kroj,Johannes Wittmann,Manfred Rohde,Anna Bierbrodt,Angelika Fruth

doi:10.3390/v12121470

Abstract

Worldwide, poultry industry suffers from infections caused by avian pathogenic Escherichia coli. Therapeutic failure due to resistant bacteria is of increasing concern and poses a threat to human and animal health. This causes a high demand to find alternatives to fight bacterial infections in animal farming. Bacteriophages are being especially considered for the control of multi-drug resistant bacteria due to their high specificity and lack of serious side effects. Therefore, the study aimed on characterizing phages and composing a phage cocktail suitable for the prevention of infections with E. coli. Six phages were isolated or selected from our collections and characterized individually and in combination with regard to host range, stability, reproduction, and efficacy in vitro. The cocktail consisting of six phages was able to inhibit formation of biofilms by some E. coli strains but not by all. Phage-resistant variants arose when bacterial cells were challenged with a single phage but not when challenged by a combination of four or six phages. Resistant variants arising showed changes in carbon metabolism and/or motility. Genomic comparison of wild type and phage-resistant mutant E28.G28R3 revealed a deletion of several genes putatively involved in phage adsorption and infection.

Highlights

Escherichia coli is among the most common pathogens in poultry and the causative agent of avian colibacillosis, which refers to localized or systemic infections, e.g., septicemia or air sac disease [1].Avian pathogenic Escherichia coli (APEC) can asymptomatically colonize chicken intestines [2] and infections most likely occur by inhalation of contaminated dust particles, followed by the development of clinical signs [1]
As a frequent disease it causes significant economic losses in poultry industry [4]. They are treated with antibiotics, which in turn promote the selection of multidrug resistant (MDR) bacteria
To our knowledge, none of these studies evaluated the use of a phage cocktail for preventing the introduction of potentially pathogenic E. coli into the flock

Summary

Introduction

Escherichia coli is among the most common pathogens in poultry and the causative agent of avian colibacillosis, which refers to localized or systemic infections, e.g., septicemia or air sac disease [1].Avian pathogenic Escherichia coli (APEC) can asymptomatically colonize chicken intestines [2] and infections most likely occur by inhalation of contaminated dust particles, followed by the development of clinical signs [1]. Bacteriophages (phages) have experienced a renaissance as alternatives to antibiotics for treating bacterial infections in humans and animals and for applications in food production [8,9,10]. They are abundant in intestinal and environmental ecosystems and offer several advantages like high specificity, self-limitation, and they lack side-effects when compared to antibiotics [11,12,13,14]. To our knowledge, none of these studies evaluated the use of a phage cocktail for preventing the introduction of potentially pathogenic E. coli into the flock

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