HAND DRYING RESEARCH

Dry Hands are Safe Hands

An awareness that microorganisms on a persons hands can be a source of cross infection and a means by which infectious diseases can be transmitted has been appreciated for over 100 years and followed on from the studies of Dr. I.P. Semmelweis who cut dramatically the death rate from infection in his delivery ward by insisting on strict hand washing and disinfection. There is no shortage of scientific papers in the medical literature on the subject but close inspection will show that the emphasis has always been on the effect of hand washing and disinfection on microbial numbers on the hands –not on what happens after washing.

Research by Dr. Tom Miller and colleagues Daniel Patrick and Glenne Findon from the Department of Medicine at the University of Auckland and published in the influential journal, Epidemiology and Infection, have produced startling results showing that hand washing is only part of the hand hygiene story. According to Dr. Miller hand drying after washing is an additional and critical factor limiting the spread of infection by touch contact. When items are touched by hands that have been washed but not dried properly many thousands of microorganisms can still be transferred. Dr. Miller quotes figures of 60,000 microorganisms being transferred to the skin of a person being touched with damp hands and 40,000 microorganisms being transferred to samples of food. Moisture left on the hands acts as abridge allowing alarmingly high numbers of bacteria to be transferred by touch contact says Dr. Miller. These figures contrast with the situation when the hands are carefully dried after washing. With proper hand drying the numbers transferring with touch contact can be reduced to less than 100.

The research, which used a recyclable textile (cloth) dispensing unit to dry the hands, has important implications for hand hygiene practices in situations where infection control is a priority. Hospitals are an obvious target but the basic principles apply equally well to other hygiene sensitive areas such as food outlets, childcare centers, rest homes for the elderly and in the family home where a caregiver might be moving between a sick member, food preparation and other domestic tasks.

One outcome of the research is that hand drying is now an regarded as an integral part of hand hygiene and most international guidelines for hand hygiene practices include a requirement for hand drying.

“Best practice” for hand hygiene

Studies carried out in the Department of Medicine, University of Auckland in recent years by Dr. Tom miller and Daniel Patrick have shown hand drying following a careful hand wash is a critical factor that determines the effectiveness of a hand hygiene practice. The research identified moisture on the hands as a potent “microbial mobilizer” and demonstrated that the degree to which microorganisms can be spread by touch contact is closely related to the level of moisture on the hands when touch contact occurs. In practical terms, hygiene facilities need to include a readily assessable hand basin, running water soap and an efficient means of hand drying.

Experiments carried out using recyclable cloth toweling dispensers have shown cloth toweling to be an effective means of hand drying. However, because the cloth is becoming progressively damp as water is removed, it is difficult to remove moisture to the level that they can be considered “safe”. The researchers have gone on to develop and test a dual system, hand drying protocol that they consider to be “Best Practice”. In the dual system that was evaluated a cloth towel from a dispensing unit was used first to remove the bulk of water left on the hands after washing. In the second phase, hands were held under a hot air towel to remove residual moisture.

Recommendations arising from the research are that the hands be dried for 10 seconds with the cloth towel followed by a further 10 seconds under an air towel. The protocol has been promoted as the 10/10 procedure. Evidence supporting the 10/10 concept is compelling. Experiments that involved subjects handling skin, food and utilities with wet hands or hands dried using the dual system,10/10, protocol demonstrated just how effective careful hand drying can be at reducing microbial transfer by touch contact.

Microbial numbers contaminating skin, food and utilities were therefore reduced 99.5%, 84% and 90% respectively when subjects dried their hands using the dual system, cloth and air towel combination. In the absence of an air towel it is recommended that residual moisture be removed using a fresh, dry section of cloth towel. i.e. two 10 second dries using the cloth toweling.

Profile of Dr. Tom Miller

Dr. Tom Miller MSc (Hon), PhD (Medicine) DSc (University of Auckland)

Dr. Miller is a Senior Research Fellow in the Department of Medicine, University of Auckland. His involvement in Biomedical research dates back to the mid 60`s and has been centered around the science of Immunobiology with a special interest in the immune defense system and its interaction with disease causing microorganisms. To date he has published 138 papers in the medical and scientific literature and in 1992 was awarded the Degree,Doctor of Science,by the University of Auckland . Dr. Miller has had a long association with ALSCO/NZTS who supported the early research carried out by himself and Daniel Patrick (MSc Hon ) into the mechanisms that control the transmission of microorganisms by touch contact. This research has had a considerable impact on understanding how disease causing microorganisms can be spread by touch contact and arose from studies that were being carried out into the problem of infection of the abdominal cavity in patients with kidney failure that were undergoing peritoneal dialysis. One theory on the origin of the infection was that the patients accidentally touched the tip of the transfer sets used to run fluid into the peritoneal cavity and transferred microorganisms from the hands into the peritoneal cavity . The resulting peritonitis was often difficult to treat and was a serious complication to a life saving therapy. In an effort to reduce the infection rate careful hand washing prior to the dialysis bag exchange was encouraged and monitored. Paradoxically it was discovered that the number of microorganisms capable of contaminating the transfer set by touch contact increased from a few hundred to many thousands after washing. The explanation was that although the individuals had been careful with their hand washing they had been less fussy about how they dried their hands. Subsequent research showed that few microorganism are transferred by touch contact with dry hands but the number can get as high as 50,000 if the hands are wet. Over the last 10 years ALSCO/NZTS has continued to support an ongoing research program investigating the relevance of hand hygiene to limiting the spread of disease in the community. The research,which has identified hand drying as an important aspect of hand hygiene, has been recognized internationally and recommendations for hand hygiene protocols almost universally now incorporate a hand drying requirement.

Dr. Miller will be contributing to the web site with background material and updates on hand hygiene issues. ALSCO/NZTS hopes that these will lead to an increased awareness of the role that effective hand hygiene can play in promoting personal and community health.

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