Study reveals connection between hand drying methods and spread of infection


Average levels of contamination 10-fold higher following hand drying with jet air dryers

A study has found that drying hands with paper towels as opposed to jet air dryers results in lower rates of virus contamination on hands and clothing.

To investigate whether micro-organisms that remain present on poorly-washed hands could be transferred beyond the washroom environment to clinical and patient areas, a study was performed in a washroom at Leeds General Infirmary, which is used by staff, visitors and patients.

It was spaced over a five-week period and investigated virus transmission beyond the washroom to surfaces in the hospital’s public and clinical areas.

Increasing the risk

And the consequences of these different rates of contamination remaining on hands after drying were measured by sampling a series of surfaces to determine the extent of transmission of a virus beyond the washroom.

The study, peer reviewed in the latest issue of Infection Control and Hospital Epidemiology, found a higher potential for microbial spread through the hospital following jet air dryer use – likely due to the increased risk of splattering on users.

This is concerning because objects and surfaces can serve as reservoirs for micro-organisms and these can be acquired via hand contact.

The significantly-greater contamination of items in close contact with healthcare professionals and patients – such as phones and stethoscopes – following jet air dryer use is particularly concerning.

And the study showed that the microbial contamination of the user’s hands or trunk following jet air dryer use was directly and indirectly transferred onto surfaces via hand, clothing or skin contact.

Measuring the impact

The findings question the use of jet air dryers and support the recommendations of German hospitals and the French SF2H that paper towels should be the prescribed method of hand drying in healthcare settings.

During the trial, a bacteriophage – a specialised virus that is harmless to humans – was used to represent microbial contamination following two types of hand drying: one using paper towels, and the other using jet air dryers.

Volunteers sanitised their hands before immersion in a liquid containing bacteriophage. They did this twice, once with each hand drying method.

Hands were then shaken three times to remove excess liquid before drying.

Volunteers also wore plastic aprons in order to be able to measure body/clothing contamination during hand drying.

All surfaces and samples investigated had bacteriophage contamination above the limit of detection following jet air dryer use.

But contamination following hand drying with paper towels occurred on only six of 11 surfaces.

For instance, simulated use of a hospital phone for 10 seconds resulted in detectable contamination following hand drying with jet air dryers.

Trunk and clothing contamination was significantly higher following jet dryers use, compared to paper towels.

Environmental sampling

On average, the levels of contamination of surfaces following hand drying with jet air dryers were 10-fold higher than with paper towels.

The researchers – Ines Moura, Duncan Ewin, and Mark Wilcox – sampled the palm and fingertips immediately after drying to measure baseline hand contamination levels before environmental sampling.

Volunteers then walked from the washroom on a pre-set route that included public and clinical areas.

Samples were collected from environmental surfaces following contact with hands or apron.

A stethoscope was also placed around the neck, leaving the chest piece and earpiece in contact with the apron for some seven minutes.

Volunteers also crossed their arms across their chest for two minutes and then rested them on the arms of a chair for three minutes.

Each surface was swabbed with a sponge-stick moistened with neutralising buffer, and surfaces were disinfected with chlorine wipes both before and after sampling.

The future

The findings support previous studies which have already established that risk of environmental bacterial contamination is lower when paper towels are used as the method of hand drying.

There was less droplet and/or microbe dispersion, and consequently lower levels of toilet surface contamination.

The researchers recommend that future studies should focus on a greater number of volunteers and potentially also include an investigation of the handwashing process prior to hand drying, exploring how the method, and lengt,h of hand washing may affect the degree of bacteriophage transfer and surface contamination.

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