Alcohol-based disinfectants and particularly handrubs are a key way to control hospital infections worldwide. Such disinfectants restrict transmission of pathogens, such as multidrug-resistant Staphylococcus aureus and Enterococcus faecium. Despite this success, healthcare-associated infections caused by E. faecium are increasing.
Pidot, et al. (2018) tested alcohol tolerance of 139 hospital isolates of E. faecium obtained between 1997 and 2015 and found that E. faecium isolates after 2010 were 10-fold more tolerant to killing by alcohol than were older isolates. Using a mouse gut colonization model of E. faecium transmission, we showed that alcohol-tolerant E. faecium resisted standard 70% isopropanol surface disinfection, resulting in greater mouse gut colonization compared to alcohol-sensitive E. faecium.
The researchers looked for bacterial genomic signatures of adaptation. Alcohol-tolerant E. faecium accumulated mutations in genes involved in carbohydrate uptake and metabolism. Mutagenesis confirmed the roles of these genes in the tolerance of E. faecium to isopropanol.
The researchers suggest suggest that bacterial adaptation is complicating infection control recommendations, necessitating additional procedures to prevent E. faecium from spreading in hospital settings.
Reference: Pidot SJ, Gao W, Buultjens AH, et al. Increasing Tolerance of Hospital Enterococcus faecium to Handwash Alcohols. Science Translational Medicine. Aug 1, 2018: Vol. 10, Issue 452.