Inhibition of Antimicrobial-Resistant Escherichia coli Using a Broad Host Range Phage Cocktail Targeting Various Bacterial Phylogenetic Groups.

Jinshil Kim,Haejoon Park,Sangryeol Ryu,Byeonghwa Jeon

doi:10.3389/fmicb.2021.699630

Jinshil Kim, Haejoon Park + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2021.699630

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Abstract

Antimicrobial-resistant (AMR) commensal Escherichia coli is a major reservoir that disseminates antimicrobial resistance to humans through the consumption of contaminated foods, such as retail poultry products. This study aimed to control AMR E. coli on retail chicken using a broad host range phage cocktail. Five phages (JEP1, 4, 6, 7, and 8) were isolated and used to construct a phage cocktail after testing infectivity on 67 AMR E. coli strains isolated from retail chicken. Transmission electron microscopic analysis revealed that the five phages belong to the Myoviridae family. The phage genomes had various sizes ranging from 39 to 170 kb and did not possess any genes associated with antimicrobial resistance and virulence. Interestingly, each phage exhibited different levels of infection against AMR E. coli strains depending on the bacterial phylogenetic group. A phage cocktail consisting of the five phages was able to infect AMR E. coli in various phylogenetic groups and inhibited 91.0% (61/67) of AMR E. coli strains used in this study. Furthermore, the phage cocktail was effective in inhibiting E. coli on chicken at refrigeration temperatures. The treatment of artificially contaminated raw chicken skin with the phage cocktail rapidly reduced the viable counts of AMR E. coli by approximately 3 log units within 3 h, and the reduction was maintained throughout the experiment without developing resistance to phage infection. These results suggest that phages can be used as a biocontrol agent to inhibit AMR commensal E. coli on raw chicken.

Highlights

Escherichia coli is the most common enteric bacteria inhabiting the gastrointestinal tract of a wide range of animals and humans (Kaper et al, 2004)
A total of eight E. coli phages were isolated from meat, sewage, and animal fecal samples (Table 1 and Supplementary Table 1) and used in phage infection assays with 67 AMR E. coli isolates from retail chicken (Figure 1A and Supplementary Tables 2, 3)
JEP4 phage infected 73.7% (28/38) of AMR E. coli strains in phylogroup A, whereas JEP1 and JEP7 phages effectively infected the strains in phylogroups B1 [69.3% (9/13) and 76.9% (10/13), respectively] (Figure 1 and Table 2)

Summary

Introduction

Escherichia coli is the most common enteric bacteria inhabiting the gastrointestinal tract of a wide range of animals and humans (Kaper et al, 2004). Due to the ubiquitousness in the intestines, commensal E. coli is likely to be exposed to orally ingested antibiotics and develops antimicrobial resistance in food-producing animals and may act as a donor and a recipient. Antimicrobial-resistant (AMR) commensal E. coli is frequently isolated from food-producing animals and their meat products (Szmolka and Nagy, 2013). Extended-spectrum βlactamases (ESBL)-producing E. coli is highly prevalent in retail poultry (Saliu et al, 2017). ESBL are β-lactamase enzymes conferring resistance to all β-lactam drugs except carbapenem and mainly located on conjugative plasmids, enhancing their rapid spread in E. coli populations and pathogenic bacterial species in the Enterobacterales order (Rupp and Fey, 2003)

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