Prevalence and Molecular Characteristics of Extended-Spectrum and AmpC β-Lactamase Producing Escherichia coli in Grazing Beef Cattle.

Shinyoung Lee,Nicolas Dilorenzo,Lin Teng,Thomas A Weppelmann,Kwangcheol Casey Jeong

doi:10.3389/fmicb.2019.03076

Shinyoung Lee, Nicolas Dilorenzo + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2019.03076

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Abstract

The emergence of extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase producing Escherichia coli represent a contemporary public health threat. ESBL and AmpC β-lactamase genes translocate between chromosomes and plasmids, facilitating rapid spread throughout the environment. In this study, ESBL/AmpC producing bacteria were isolated from beef cattle farms with seldom antibiotic use. Eleven farms out of 17 tested, had ESBL/AmpC producing E. coli in animals, soil, and forage samples. Fifty-nine CTX-M or CMY-2 positive E. coli isolates were further characterized with whole-genome sequencing. The isolates commonly carried CMY-2, TEM, or CTX-M genes, and over half encoded both CTX-M and TEM genes. Using comparative genomics, antimicrobial resistance genes from 12 classes of antimicrobial were identified and confirmed by antibiotic susceptibility test, revealing multidrug resistance against multiple classes of antibiotics. Virulence factors related to adherence, invasion, iron uptake, and bacterial secretion systems were shared by all isolates; some of which were identified as enteropathogenic E. coli. Phylogenetic analyses revealed a pattern of close genetic relatedness, suggesting that ESBL/AmpC producing E. coli were transmitted among farms as well as independent evolution within farms. Our results indicate that ESBL and AmpC β-lactamases prevail in food animal production system regardless antibiotic use and have the characteristics for zoonotic transmission.

Highlights

Extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase have become prevalent in Enterobacteriaceae, representing a contemporary public health threat (Rawat and Nair, 2010)
All commercial cow/calf operations tested in this study contained either CTX-M or CMY-2 positive bacteria, and more than half of the farms carried both CTX-M and CMY-2 producing E. coli
The prevalence and concentration of CTX-M or CMY-2 genes were high in environmental samples, and environmental isolates were closely related to isolates from cattle feces

Summary

Introduction

Extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase have become prevalent in Enterobacteriaceae, representing a contemporary public health threat (Rawat and Nair, 2010). Due to the increased use of β-lactams and subsequent relocation of ESBL and AmpC β-lactamase genes to plasmids, ESBL/AmpC producing E. coli are widely disseminated into the environment and into the food-producing animals (Blaak et al, 2014; Ma et al, 2018, 2019). This allows for zoonotic transmission to humans through contaminated food products, creating a feedback loop for evolution and positive selection of new resistance genes (Ewers et al, 2012; Ibrahim et al, 2016). The emergence of β-lactam resistant bacteria in food-producing animals represents both a challenge to global health and a potential critical control point (Doi et al, 2013; Petty et al, 2014)

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