Anywhere we repeat a procedure over and over and over again, whether it’s in a hospital or at home or anywhere else, you’re giving bacteria an opportunity to adapt Tim Stinear

But while rates of golden staph infection have been decreasing for the last 15 years, a new threat emerges: Enterococcal bacteria, which are a normal part of the human gut bacteria and don’t usually cause health problems, are becoming more prevalent in hospitals and can cause infections that are very difficult to treat. Especially bacteria of the species Enterococcus faecium seem to thrive, leading to increased number of infections.

One particularly problematic group of enterococci are those that develop resistance to the last-line antibiotic, vancomycin. These bacteria are known as vancomycin resistant enterococci (VRE). These are particularly dangerous for patients undergoing antibiotic treatment, because the medication takes out their gut microbiome. “When your natural gut bacteria are disturbed you can become prone to VRE, in the context of a health-care institution”, says Professor Tim Stinear from the Peter Doherty Institute for Infection and Immunity. The research team took 139 different strains of E. faecium and treated them with isopropanol solution, an alcohol commonly used in hand sanitisers. “We started testing to see whether they had any tolerance to alcohol, and sure enough, the new isolates were more tolerant to alcohol exposure than the older isolates.”

Professor Stinear says this is an unfortunate side effect of the success of the hygiene program. “Alcohol use in hospitals has gone from hundreds of litres a month to thousands of litres a month of these alcohol-based disinfectants. “Anywhere we repeat a procedure over and over and over again, whether it’s in a hospital or at home or anywhere else, you’re giving bacteria an opportunity to adapt, because that’s what they do, they mutate. The ones that survive the new environment better then go on to thrive.” And the risk increases when the guidelines aren’t followed.