While antibiotic treatment is a well-known cause of antibiotic-resistant bacterial strains, new research shows that selection pressures occurring far before the widespread use of antibiotics have also been a contributing factor.

Scientists from Norway and the UK used recently developed technology to create an evolutionary timeline of Enterococcus faecalis, a common source of antibiotic-resistant septic infections in hospitalized patients around the world.

The researchers analyzed around 2000 blood and stool samples collected from animals and health humans dating from 1936 to the present that contained E. faecalis. They sequenced the genome of each bacterial sample and were able to map the evolutionary changes over time. Surprisingly, they discovered that antibiotic-resistant strains arose earlier than expected – before antibiotics became the gold standard for treating bacterial infections.

Their findings suggest that E. faecalis can adapt very quickly to selection pressures. They propose that early agricultural and medical practices, such as the use of arsenic and mercury, played an integral part in the evolution of superbug strains that are still around today.

Due to the flexibility of this bacterial species to evolve antibiotic resistance, the scientists suggest that patients should be screened for E. faecalis when being admitted to a hospital in order to reduce the odds of developing and/or spreading infections within the healthcare setting.

TransPharm Preclinical Solutions has validated several mouse and rat disease models using E. faecalis including gastrointestinal infection, soft tissue infection, bacteremia, and peritonitis. Additional validations are available upon request. Contact us to request a free, no-obligation quote or to receive a complimentary consultation about your upcoming research project.