Genomic content typifying a prevalent clade of bovine mastitis-associated Escherichia coli.

Robert J Goldstone,David G E Smith,Susan Harris

doi:10.1038/srep30115

Robert J Goldstone, David G E Smith + Show 1 more

Open Access

https://doi.org/10.1038/srep30115

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Journal: Scientific Reports	Publication Date: Jul 20, 2016
Citations: 40	License type: CC BY 4.0

Affiliation: Heriot-Watt University

Abstract

E. coli represents a heterogeneous population with capabilities to cause disease in several anatomical sites. Among sites that can be colonised is the bovine mammary gland (udder) and a distinct class of mammary pathogenic E. coli (MPEC) has been proposed. MPEC are the principle causative agents of bovine mastitis in well-managed dairy farms, costing producers in the European Union an estimated €2 billion per year. Despite the economic impact, and the threat this disease presents to small and medium sized dairy farmers, the factors which mediate the ability for E. coli to thrive in bovine mammary tissue remain poorly elucidated. Strains belonging to E. coli phylogroup A are most frequently isolated from mastitis. In this paper, we apply a population level genomic analysis to this group of E. coli to uncover genomic signatures of mammary infectivity. Through a robust statistical analysis, we show that not all strains of E. coli are equally likely to cause mastitis, and those that do possess specific gene content that may promote their adaptation and survival in the bovine udder. Through a pan-genomic analysis, we identify just three genetic loci which are ubiquitous in MPEC, but appear dispensable for E. coli from other niches.

Highlights

E. coli represents a heterogeneous population with capabilities to cause disease in several anatomical sites
Escherichia coli is a diverse group of Gram-negative bacteria that can colonise and exploit a range of environments and hosts[1]
In order to capture the breadth of the population of phylogroup A E. coli in mastitis, we confirmed the position of sixty-two newly sequenced E. coli mammary pathogenic E. coli (MPEC), isolated from several countries, into phylogroup A

Summary

Introduction

E. coli represents a heterogeneous population with capabilities to cause disease in several anatomical sites. Escherichia coli is a diverse group of Gram-negative bacteria that can colonise and exploit a range of environments and hosts[1] These bacteria often asymptomatically colonise the digestive tract of mammals, various E. coli types can cause severe gastrointestinal disease and a range of extra-intestinal infections in both humans and animals[2,3]. Several studies have shown that the vast majority of E. coli isolates from cases of bovine mastitis (termed mammary pathogenic E. coli, or MPEC) originate from within these two phylogroups[10,11,12,13,14]. This, along with the evidence that the molecular diversity of mastitis isolates compared with other E. coli is limited[10,22], supports the conjecture that the bovine udder environment presents a milieu which is selective against the successful colonisation by some E. coli strains, yet is permissive for others. Blum et al.[21] analysed the genome sequences of three www.nature.com/scientificreports/

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