Photo Credit – CDC
# 7854
Over the past decade, alcohol-based hand sanitizers have become ubiquitous in modern society – both in medical facilities, and in the pockets and purses of millions of people. Their popularity stems from the fact that they are quick and easy to use, require no water or wash basin, and in many scenarios offer pretty good protection against germs.
While they are not always an appropriate substitute for a good old-fashioned soap & water hand scrubbing - particularly when dealing with C. difficile (see CDC C. Diff FAQ) or Norovirus (see CMAJ: Hand Sanitizers May Be `Suboptimal’ For Preventing Norovirus) - I confess, I keep a bottle handy almost everywhere I go.
And I use it often.
With Global Handwashing Day just two days away, and cold & flu season upon us, it is good timing that a study just published in BMC Infectious Disease looks at the efficacy of using alcohol hand sanitizers, focusing in particular on how much sanitizer is really needed to do a good job.
And as it turns out, if you follow the directions on the bottle, you may not be getting the degree of disinfection you believe. The following figure shows a composite (across 15 subjects) of areas of the hands that escaped sanitation during one of the trials conducted using the the manufacturer’s recommended quantity of product (1.1 ml).
It turns out that while alcohol based sanitizers work well against most common pathogens, the quantity of product recommended by many manufacturers (typically 1.1 ml, or a `single pump’ from the dispenser) provides inadequate coverage (both in terms of skin area and contact time) to meet current ASTM efficacy standards.
A `double-pump’ (ie. > 2 ml) provided not only better skin coverage, but longer contact time, resulting in a much greater reduction of skin contamination – meeting or exceeding ASTM and FDA efficacy standards.
A link to the study, along with some excerpts, then I’ll be back with a bit more.
Less and less–influence of volume on hand coverage and bactericidal efficacy in hand disinfection
Günter Kampf12*, Sigunde Ruselack3, Sven Eggerstedt3, Nicolas Nowak4 and Muhammad Bashir5
BMC Infectious Diseases 2013, 13:472 doi:10.1186/1471-2334-13-472
The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2334/13/472
Abstract
Background
Some manufacturers recommend using 1.1 mL per application of alcohol-based handrubs for effective hand disinfection. However, whether this volume is sufficient to cover both hands, as recommended by the World Health Organization, and fulfills current efficacy standards is unknown. This study aimed to determine hand coverage for three handrubs (two gels based on 70% v/v and 85% w/w ethanol and a foam based on 70% v/v ethanol) applied at various volumes.
Methods
Products were tested at product volumes of 1.1 mL, 2 mL, 2.4 mL as well as 1 and 2 pump dispenser pushes; the foam product was tested in addition at foam volumes of 1.1 mL, 2 mL, and 2.4 mL. Products were supplemented with a fluorescent dye and 15 participants applied products using responsible application techniques without any specific steps but the aim of completely covering both hands. Coverage quality was determined under ultraviolet light by two blinded investigators. Efficacy of the three handrubs was determined according to ASTM E 1174-06 and ASTM E 2755-10. For each experiment, the hands of 12 participants were contaminated with Serratia marcescens and the products applied as recommended (1.1 mL for 70% v/v ethanol products; 2 mL for the 85% w/w ethanol product). Log10-reduction was calculated.
Results
Volumes < 2 mL yielded high rates of incomplete coverage (67%–87%) whereas volumes ≥ 2 mL gave lower rates (13%–53%). Differences in coverage were significant between the five volumes tested for all handrubs (p < 0.001; two-way ANOVA) but not between the three handrubs themselves (p = 0.796). Application of 1.1 mL of 70% v/v ethanol rubs reduced contamination by 1.85 log10 or 1.60 log10 (ASTM E 1174-06); this failed the US FDA efficacy requirement of at least 2 log10. Application of 2 mL of the 85% w/w ethanol rub reduced contamination by 2.06 log10 (ASTM E 1174-06), fulfilling the US FDA efficacy requirement. Similar results were obtained according to ASTM E 2755-10.
Conclusions
Our data indicated that handrubs based on 70% ethanol (v/v) with a recommended volume of 1.1 mL per application do not ensure complete coverage of both hands and do not achieve current ASTM efficacy standards.
Actually, the entire (open access) study is worth reading, but for those not particularly interested in methods and materials, the Discussion at the end wraps things up nicely.
As a former paramedic - I was, and still am - fanatical about hand hygiene. So we’ve looked at the topic of hand washing, and Hospital Acquired Infections (HAIs) often.
Last June, in The Great Unwashed, we looked at a Michigan State University study that found only about 5% of people who were observed in public restrooms washed their hands effectively. While in Before You Ask To Borrow Someone’s Cell Phone . . . we looked at the degree of fecal (and other) contamination on fomites (inanimate objects like cell phones, keyboards, credit cards, money . . . )
We live in a germy world, and you don’t have to work in a hospital or a doctor’s office to be concerned with good hand hygiene.
For more on all of this I’d invite you to visit:
http://www.globalhandwashingday.org/
And the CDC’s hand hygiene website, where you will find many resources, including a link to a new iPad/iPhone application called iScrub.
