The Surprise Attack—An Increase in Bacterial Resistance to Disinfecting Products

Alcohol-based hand sanitizer is as much a constant in hospitals as the need to use it. Cleaning and disinfection practices are one of the strongest tools in the infection prevention toolbox. The ability to appropriately clean surfaces, medical equipment, and our own hands in a health care setting is vital to stopping the spread of infectious diseases. As the threat of highly drug-resistant organisms continues to increase with the growing presence of carbapenem-resistant Enterobacteriaceae and the mcr-1 gene, the ability to prevent the spread and microbial burden becomes that much more vital.

On one hand (pun intended), the use of new disinfecting technologies, like UV-disinfecting machines, is considered by those in charge of purchasing infection prevention equipment with increasing frequency as the health care community looks to new efficient and effective methods to offending pathogens. On the other hand, as we become a more environmentally-focused population, health care organizations are exploring the prospect of "green" infection prevention techniques.

Disappointingly, neither of these discussions involves examining the efficacy of disinfecting hand washes. In a world obsessed with new technologies and growing scrutiny of our environmental footprint, how did we forget the most important aspect of infection control: hand hygiene. The results of a new study indicate that we are ignoring the efficacy of existing disinfectants clinicians use to complete this simple task at our own peril.

Grounds for the study began with investigators in Melbourne, Australia, who were concerned about the prevailing presence of Enterococcus faecium in their facilities. Specifically, they were concerned with the incidence of vancomycin-resistant Enterococci (VRE) in hospitals, despite disinfection and hand hygiene. The investigators noted that despite a greater focus on hand hygiene and the presence of hand rubs and washes that include isopropyl or ethyl alcohol, E faecium (including VRE) infections were increasing in hospitals. Was it possible that this bug had become resistant to alcohol-based hand disinfectants?

The investigators screened 139 E faecium isolates/samples collected between 1997 and 2015 across 2 hospitals in Melbourne. The goal was simple: to see how well these isolated bacteria managed against diluted isopropyl alcohol. The results were startling.

Those isolates collected after 2009 showed more tolerance to the alcohol product than samples collected before 2004.

Based on these results, the investigators decided to take their research a step further to determine how these “more resistant” E faecium fared in an environment cleaned with isopropyl alcohol. To accomplish this, they placed different E faecium isolates onto the floors of cleaned mouse cages. The results indicated that those isolates that were more alcohol-tolerant also better colonized the guts of the mice in the cages that had been cleaned with isopropyl alcohol wipes.

Further genomic analysis found that the more-tolerant bacteria had gone through several mutations which strengthened their metabolisms to allow for increased alcohol resistance.

These findings are disquieting as they indicate that the efficacy of our steadfast product—alcohol-based hand sanitizer—may be creating a damning future that includes not just antimicrobial resistance, but also disinfectant resistance. The bulk of our attention of late has been on antimicrobial resistance; however, we must address additional emerging threats such as resistance to the disinfecting products we so desperately rely on. We need to focus more efforts on research to understand how the bacterial culprits of health care-associated infections are responding to cleaning and disinfecting products. As the investigators on this study have revealed, bacteria may be becoming resistant to such products slowly over time and we simply cannot hesitate to understand and respond to this growing threat. Now, more than ever, we must focus on strategies for preventing and control resistance across both platforms—antimicrobials, and disinfectants.