alcohol hand sanitizer

Researchers at the University of Melbourne investigated why, despite the widespread use of hand sanitizers, infection rates from certain types of antibiotic-resistant bacteria are increasing in Australian hospitals.

Nosocomial infections are infections acquired in hospitals. Most of these hospital-acquired infections are bacterial. However, antibiotic use in hospitals means that the risk of antibiotic resistance is greater, making nosocomial infections potentially more difficult to treat.

Although any patient can potentially contract a nosocomial infection, patient risk for infection is higher when the patient:

  • Is an infant or is elderly
  • Has an indwelling catheter
  • Is on a ventilator
  • Is on antibiotics or histamine receptor blockers
  • Has a medical condition or is receiving a treatment that compromises the immune system

Hospital Infection Prevention

Attention to simple preventative measures can significantly reduce the transmission of hospital infections. Encouraging the public and hospital workers to get yearly flu vaccinations is another effective means of reducing the transmission of nosocomial infections.

Handwashing and strategies for handwashing compliance are also simple ways to minimize the spread of hospital-acquired infections. Since some types of bacteria can live on surfaces for days or weeks. As a result, hospital infection prevention protocols include procedures for ensuring that medical surfaces are cleaned and disinfected.

In addition, most hospitals have installed ethyl alcohol- or isopropyl alcohol-based hand sanitizer stations in high-traffic areas such as by entrances and elevators. Hospitals started using alcohol-based disinfectants in 2002.  By 2015, hospital alcohol hand sanitizer use increased ten-fold to 1,000 liters per month.

Despite measures such as these, researchers in Melbourne, Australia noticed that, although hospital-acquired Staphylococcus aureus infections rates were significantly lower, hospital-acquired infections caused by the bacteria Enterococcus faecium were increasing.  They wondered if this was because the E. faecium bacterium were more resistant to disinfectants.

Ethyl Alcohol and Isopropyl Alcohol Hand and Surface Sanitizers

The results of their study were recently published in Translational Medicine. They examined 139 samples of E. faecium bacteria taken from two hospitals in Melbourne between 1997 and 2015.  Each sample was grown and then exposed to diluted isopropyl alcohol (commonly found in hand sanitizers) to test for alcohol tolerance.

In a second phase of the study, the same bacteria were grown, planted on the floor of mice cages, and then cleaned with alcohol-based disinfectants. Control experiments were also conducted using water. Infection and infection severity data was recorded and analyzed.

The researchers found that bacteria from 2009 onwards were more resistant to the disinfectants than those from prior to 2004. Moreover, the alcohol-resistant bacteria were also more aggressive in infecting.

This study is important because it points to the possibility that an antibiotic-resistant strain of bacteria can also became resistant to being killed by a disinfectant. The research team concluded that, “Global efforts to mitigate bacterial resistance should consider how microbes can adapt not only to drugs, but also to alcohols and other ingredients used in disinfectants.”

Written by Debra A. Kellen, PhD

Reference:  Pidot, S. J., Gao, W., Buultjens, A. H., Monk, I. R., Guerillot, R., Carter, G. P., … & Mahony, A. A. (2018). Increasing tolerance of hospital Enterococcus faecium to handwash alcohols. Science Translational Medicine10(452), eaar6115.         DOI: 10.1126/scitranslmed.aar6115

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