A bacteria called Enterococcus faecium is a leading cause of hospital-acquired infections, and it's been shrugging off antibiotics at an increasing rate, said senior researcher Timothy Stinear.
"It is a WHO [World Health Organization] and CDC-recognized superbug," Stinear said. "In the hospital, it is already resistant to nearly all classes of antibiotics." Now E. faecium appears to be developing resistance to alcohol-based sanitizers, possibly in response to the broad use of the antimicrobial gels in hospital hand-hygiene programs, Stinear and his colleagues have found.
"E. faecium has adapted to the health-care environment," Stinear said. E. faecium and other enterococci are bacteria found in the gut, and typically are not hostile or harmful, the researchers said in background notes.
Cause of hospital-associated bacterial infections
However, these germs have emerged as a significant cause of hospital-associated bacterial infections, the study authors noted. This family of bacteria account for a tenth of hospital-acquired bacterial infections worldwide and are the fourth and fifth leading cause of blood poisoning in North America and Europe, respectively.
According to Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security, "E. faecium is a highly prevalent bacterial species that is a prevalent cause of infections that range from bloodstream infections to urinary tract infections." Adalja was not involved with the new study but was familiar with the findings.
"The vancomycin antibiotic-resistant form of this bacteria, which the CDC [U.S. Centers for Disease Control and Prevention] estimates kills more than 1,000 people a year in the U.S., is a priority pathogen that is involved in many hospital-acquired infections," Adalja explained.
In the new study, Stinear's team collected 139 E. faecium samples between 1997 and 2015 from two Melbourne hospitals and exposed them to diluted isopropyl alcohol, to see how effectively alcohol would kill off the bugs.
Bacteria samples dating from 2009 onward were on average more resistant to alcohol, compared with bacteria collected before 2004. To see whether this resistance would translate into more infections, the researchers introduced different strains of E. faeciumonto the floors of mouse cages.
They then wiped down the ages with isopropyl alcohol wipes, which should have effectively disinfected them. Bacteria that had developed a resistance to alcohol sanitizers were better able to dodge disinfection and colonize the guts of mice placed in the cages, the findings showed.