Evolution of strains of E. coli from farm animals to humans


E.coli typically live as harmless bacteria in the gastrointestinal tracts of birds and mammals, but also reside in environments such as water and soil and in food products, such as turkey and chicken meat. E.coli is the main source of urinary tract infections and can also lead to sepsis and meningitis.

A new drug-resistant strain of E.coli

The study, conducted by the University of Technology Sydney, aimed to better understand the evolutionary and genomic characteristics of an emerging strain of E.coliknown as ST58, which is on the rise, especially in parts of Europe, and is also more drug resistant.

Dr Cameron Redi, from the university, said: “Our team analyzed the genomes of E. coli ST58 from over 700 human, animal and environmental sources around the world, to look for clues as to why which it is an emerging cause of sepsis and urinary tract infections.We have found that E.coli ST58 from pigs, cattle, and chickens contains bits of genetic material, called CoIV plasmids, that are characteristic of this strain of the pathogen. E.coli.”

Plasmids are tiny double-stranded DNA molecules, separate from the bacterial chromosome, which can independently replicate and transfer through different E.coli strains, favoring the evolution of virulence. Acquisition of CoIV plasmids can prime E.coli strains to cause additional intestinal infections in humans and also increase the likelihood of antimicrobial resistance, research suggests.

“Zonoses, particularly in relation to E.coli, should not be viewed simply as the transfer of a pathogen from an animal to a human,” said research co-author Professor Steven Djordjevic. “It should rather be understood as a complex phenomenon resulting from a vast network of interactions between groups of E.coli (and other bacteria), and the selective pressures they encounter in humans and animals,” he said.

Poultry in the context of the evolution of this pathogen

The results suggest that the 3 main sectors of food animal production (poultry, cattle and pigs) served as the backdrop for the evolution and emergence of this pathogen.

The study has broad implications for public health policy that span the entire food, veterinary and clinical industry, according to Dr. Reid.

“Ideally, with the advent and widespread adoption of genome sequencing technology, future infectious disease public health can shift to a primarily proactive discipline, where genomic surveillance systems are able to predict the emergence of pathogens and inform effective interventions.”

For such a system to work, continued collaboration between governments, public health agencies, food producers and clinicians is needed, and this would involve monitoring a variety of non-human sources of microbes.

“This would include domestic and wild animals – especially birds – foodstuffs, sewers and waterways – in what is called a ‘One Health’ approach. Certain microbes, such as ST58 E.coliknow very few barriers between these increasingly interconnected hosts and environments.

“A One Health genomic pathogen surveillance system would be a revolution in the field of public health and would go a long way to breaking down approaches that have historically been human-centric and devoid of any connection to the world around us.

*A role for CoIV plasmids in the evolution of pathogenic Escherichia coli ST58 has been published in the journal Nature Communications


Comments are closed.