Author(s): Charles Jacob, Riley Weaver, Braden Francom
Mentor(s): Lauren Brooks
Institution UVU
The most commonly used hand-cleaning agents used in hospitals and households around the world are alcohol-based. However, in some cases, certain bacteria, most prominently Enterococcus spp., have demonstrated the ability to evolve tolerance to these disinfectants in response to repeated exposures in a hospital setting. This study aims to identify whether selected members of the Staphylococcus genus can evolve tolerance to ethanol. Staphylococcus spp. are common skin microbiota, with some taxa associated with beneficial interactions (S. hominis and sometimes S. epidermidis), while others are associated with infections (S. aureus and sometimes S. epidermidis). A directed evolution experiment was conducted in which the three Staphylococcus species were exposed to increasingly higher ethanol concentrations. The minimum lethal dose for baseline Staphylococcus cultures ranged from 35 to 50%. After several generations of exposure to sub-lethal doses, ethanol resistance increased, resulting in tolerance to 60% ethanol or more. This demonstrates the capacity of these bacteria to develop tolerance when subjected to repeated ethanol stress. The clinical implications for this finding are substantial. The long-term effectiveness of alcohol-based sanitizers in areas such as hospitals may become compromised, leading to an increase in hospital-acquired infections. Current research is ongoing to determine the maximum possible level of evolved tolerance, and future research will investigate the specific mechanisms by which members of the Staphylococcus genus accomplish this to better predict and mitigate the potential impacts on healthcare delivery.