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Some solutions sound intuitive. But common sense doesn’t always pan out. When it comes to hand hygiene, it is logical that transmission of infectious agents should be reduced if you don’t have to touch various surfaces. But, is that borne out in practice?
Electronic faucets are one such example. The idea is great. You don’t have to touch the faucet to turn it on. It simply turns on when it senses the presence of your hands beneath the faucet. In our May 2011 What's New in the Patient Safety World column “The Best Laid Plans,,,Electronic Water Faucet Paradox” we noted that researchers at Johns Hopkins demonstrated 50% of electronic water faucets grew Legionella species, compared to 15% of manual faucets. They felt that the complex valve structure of the electronic faucets predisposed to growth of Legionella. While some wanted more studies to confirm this finding, Hopkins was so concerned that they removed 20 electronic faucets in patient care areas and cancelled planned installation of about 1000 such faucets in a new clinical building.
Now a new study questions use of high speed air dryers (Moura 2021). These are devices that blow warm or hot air over your hands to dry them off after you wash them. Theoretically, if you don’t have to touch the device, you would be less likely to get contamination compared to touching a paper towel dispenser. Moura et al. used a bacteriophage as a surrogate for bacterial pathogens and compared bacteriophage counts on volunteers’ hands dried via high speed air dryers vs. those dried by paper towels. The volunteers first cleansed their hands or gloved hands in 70% alcohol gel, then immersed their hands in the study solution containing the bacteriophage. The researchers then measured bacteriophage levels not only on the volunteers’ hands, but also on their clothing and on surfaces they might touch (eg. stethoscope, arms of a chair, and several other surfaces).
Both the jet air dryer and the paper towel methods significantly reduced bacteriophage contamination of the hands. But, apron (simulated trunk or clothing) contamination by bacteriophage during hand drying was significantly higher after jet air dryer use. The bacteriophage levels detected on the volunteers’ hands at the end of the experiments suggested gross persistence of bacteriophage contamination throughout the sampling period.
Moreover, all 8 surfaces investigated following jet air dryer use had bacteriophage contamination above the limit of detection, whereas this occurred for only 5 surfaces after paper towel use. For all samples, there was a significantly higher level of surface contamination following hand drying with the jet air dryer than with paper towels. Samples obtained from smaller surface areas, namely elevator and ward access buttons, showed lower bacteriophage contamination. Interestingly, simulated use of a hospital phone for 10 seconds resulted in detectable contamination only following jet air dryer use. The average surface contamination following hand contact was >10-fold higher after jet air dryer use than after paper towel use (4.1 log10 copies/µL versus 2.9 log10 copies/µL, respectively).
This, of course, is not the first study to warn of potential contamination from high speed air dryers. Best et al. (Best 2018) compared bacterial contamination levels in washrooms with hand-drying by either paper towels (PT) or jet air dryer (JAD). Bacterial contamination was lower in PT versus JAD washrooms. Total bacterial recovery was significantly greater from JAD versus PT dispenser surfaces and significantly more bacteria were recovered from JAD washroom floors. Multiple examples of significant differences in surface bacterial contamination, including by fecal and antibiotic-resistant bacteria, were observed, with higher levels in JAD versus PT washrooms. The authors concluded that hand-drying method affects the risk of (airborne) dissemination of bacteria in real-world settings.
The findings of these studies certainly question the use of hand drying with jet air dryers in a hospital setting.
Moura I, Ewin D, Wilcox M. From the hospital toilet to the ward: A pilot study on microbe dispersal to multiple hospital surfaces following hand drying using a jet air dryer versus paper towels. Infection Control & Hospital Epidemiology 2021; 1-4
Published online 17 March 2021
Best E, Parnell P, Couturier J, et al. Environmental contamination by bacteria in hospital washrooms according to hand-drying method: a multicentre study. J Hosp Infect 2018; 100: 469-475
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