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Cambridge University Science Magazine
The commensal gut bacterium is commonly found in hospitals and can cause life-threatening infections in immunocompromised patients. Antibiotic resistance is common in this species, with over 18% of isolates studied harbouring antibiotic resistance genes.

In a recent study published in Nature Communications, scientists from Wellcome Sanger Institute, University of Oslo, and University of Cambridge collaborated to elucidate the evolution of E. faecalis. To understand how human behaviours, agriculture, and medicines have influenced the development of different strains of the bacterium, the researchers sequenced the genomes of 2027 bacterial isolates from clinical and non-clinical sources ranging from the pre-antibiotic era in 1936 to 2018.

Sequencing the bacterial genomes revealed broad genetic similarities between isolates collected from humans, wild birds, farm animals, and the environment. The genetic similarity between isolates from different environments indicates that these bacteria are ecological generalists with relatively little adaptation to different host species.

The researchers found that 18% of the isolates possessed antibiotic resistance genes, with 54% collected from hospital patients. Sequencing of isolates collected between 1940–1985 revealed acquired antibiotic resistance genes as early as 1960. Antibiotic resistance was also common in isolates collected from wild birds, likely reflecting the spread of antibiotic resistant strains across host species. These data highlight the urgent need for better screening programmes to prevent further spread of untreatable bacterial strains.

Lauren Lee is a BlueSci contributor.