A new study led by a research team from Massachusetts Eye and Ear and Harvard Medical School describes how bacteria adapted to the modern hospital environment and repeatedly cause antibiotic-resistant bloodstream infections. Infections acquired by hospitalized patients are more often antibiotic-resistant than those that occur elsewhere, and hospitals invest considerable effort to prevent them.

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Despite best efforts, some bacteria are able to persist and circulate among patients, causing repeated infections. This study examined one of the first sustained hospital outbreaks of a multidrug-resistant bacterium, Enterococcus faecalis, which occurred from the early through the mid-1980s, causing over 60 outbreak strains.

The study, published online April 10 in Science Translational Medicine, was led by a research team headed by Michael Gilmore, PhD, Senior Scientist at Mass. Eye and Ear, and the Sir William Osler Professor of Ophthalmology, and Director of the Infectious Disease Institute in the Department of Ophthalmology at Harvard Medical School. The team compared the DNA sequences of bacteria that had been archived from the outbreak 30 years ago by collaborator Mark M. Huycke, MD, infectious disease specialist now at the University of Oklahoma Health Sciences Center. Spearheaded by Gilmore laboratory research associate Daria Van Tyne, PhD, and with the help of Broad Institute Scientist Ashlee Earl, PhD, the researchers identified mutations in the bacteria as they caused one infection after another over 4 years.

The study’s authors hope the novel findings on how enterococci infect the bloodstream will help scientists and physicians develop new ways to prevent these infections from happening, and to better treat them when they occur.

“Knowing how the microbes outsmarted the body’s immune system and antibiotics tells us what is critical to the microbe in order to cause infection,” says Dr. Gilmore. “This in turn gives us a clearer shot at new targets for developing the next generation of antibiotics, and for guiding their careful use inside and outside of hospitals.”

Read more at Massachusetts Eye and Ear Infirmary