journal of Hospital Infection (200 I) 48 (Supplement A): %-SE
doi: IO. I053/jhin.2001.0972,
available online at http://www.idealibrary.com
Arguments
for alcoholic
M
on rDEkl@
hand disinfection*
M. L. Rotter
Hygiene Institute of the University, Kinderspitalgasse IS, A- I 095 Vienna, Austria
The non-aqueous
use of ethanol or propanols
offers various advantages over washing hands
Summary:
with either unmedicated
or medicated soap in both hygienic and surgical hand disinfection.
Alcohols exert
the strongest and fastest activity against a wide spectrum of bacteria and fungi (but not bacterial spores) as
well as enveloped (but less so against non-enveloped)
viruses, being little influenced
by interfering
substances. They are of low toxicity
and offer acceptable skin tolerability
when made up with suitable emollients. The mode of their application
is simple and three to four times more economical of time than wash
procedures, features which help to increase the compliance
with the rules of hand hygiene.
0 200 I The Hospital
Keywords: Hygienic
hand disinfection;
surgical
hand disinfection;
Introduction
Although
he studied and worked in the wine growing area of Vienna, Ignaz Semmelweis neither used
nor advocated alcohol for hand disinfection;
rather
he employed
chlorine-releasing
agents such as
sodium hypochlorite
and chlorinated
lime.’ Several
decades later, however, alcoholic
hand-rubs
have
become the preferred preparations
for both hygienic
and surgical hand disinfection
in German-speaking
countries. In a survey of methods of hand hygiene
in 130 German and Austrian
intensive care units,
98% used alcoholic rubs only, 1% used both rubs
and disinfectant-detergents
and 1% employed
only
non-medicated
soap and water.’ It should also be
mentioned
that, in North America,
although alcohols have been avoided for allegedly adverse effects
on the skin until very recently, they were successfully used for surgical scrubbing in the 1940~.~ This
is because the use of non-aqueous
ethanol
or
propanols
offers various advantages over washing
hands with either unmedicated
or medicated
soap.
*Presented
at the 6th International
BODE Hygiene
Days
Vienna, 7-9 September
2000.
Author
for correspondence:
Manfred
L. Rotter, Hygiene
Institute
of the University,
Kinderspitalgasse
15, A-1095
Vienna, Austria.
0 195-670 I/O I /OAOOS4 + 05 $35.00/O
in
skin tolerability;
flammability;
Infection
Society
flash point.
In this article it will be shown that alcohols exert an
excellent antimicrobial
activity which is more rapid
than other disinfectants,
with a wide antimicrobial
spectrum,
being little
influenced
by interfering
substances such as an ion-rich
environment,
protein or blood, and detergents.
Alcohols are of low
toxicity
and offer an acceptable
skin tolerability.
The mode of their application
is simple and fast.
Methods
Antimicrobial
and results
activity
When used for hygienic
hand disinfection
(i.e.,
health care personnel handwash), which is directed
exclusively
against transient hand flora, the antimicrobial effect of alcoholic rubs far exceeds that of
handwashing
with both unmedicated
and medicated
soap. This is illustrated
in Table I where examples
from experiments
with artificially
contaminated
hands of volunteers
are given. Here it can also be
seen that the antimicrobial
efficacy of alcoholic rubs
is not only directly related to the concentration
but,
when comparing
mean loglo reduction
factors of
corresponding
concentrations,
that there is also a
clear ranking of order in the efficacy of the alcohols:
ethanol is less effective than iso-propanol,
the performance of which is inferior to that of n-propanol.
0 200 I The Hospital
Infection
Society
Alcoholic
hand
s5
disinfection
Table
I Examples fir the antibacterial
contaminated with Escherichia coii.*
Agent
eficacy
Concentration
Handwash
Unmedicated
liquid soap
Povidone-iodine
liquid soap
Chlorhexidine
gluconate
(detergent)
Triclosan (detergent)
2-Biphenylol
(detergent)
Handrub
Tosylchloramide
(aqueous solution)
Povidone-iodine
(aqueous solution)
Chloro-cresol
(aqueous solution)
Hydrogen peroxide
Ethanol
3.1
4
0. IT
2.0t
2.8
2.6
4
4
2.0t
4.2
7
I .ot
4.04.3
8
I .ot
3.6
9, IO
7.5t
3.6
3.8
3.8-4.3
4.5
3.9
4.0-4.4
4.84.9
4.3
4.7-5.0
5.5
5.8
II
I2
5,12,13,
14, I5
I2
I2
4.6, 14. I6
8, I2
I2
12, I4
I2
I7
50*
70*
40*
50*
6’3$
I oo+
I min. tw/v;
Reference
4.0t
6’3
of all treatments:
artificially
4.536
4
70*
*Duration
Mean log,a of
reduction factor
of hands
2.7-3.0
3.5
80$
n-Propanol
treatments
0.75t
64
Iso-propanol
(%)
of various
*v/v.
Laboratories
in Vienna, Mainz and Birmingham
undertook
parallel experiments
to test the efficacy
of washing hands with a biphenylol
and a povidoneiodine liquid soap versus rubbing hands with 70%
(v/v) ethanol plus 0.5% chlorhexidine
gluconate,
60% (v/v) isopropanol
or 50% (v/v) n-propanol.
A
using
arcsine
transformation,
power
analysis
showed that, in order to demonstrate
a tested product as significantly
inferior to a reference disinfection procedure with iso-propanol
60% (1 min), there
has to be a difference of approximately
0.6 between
the mean loglo reduction
factors for the two procedures using 15 volunteers, at tx (uni-directional)
= 0.1
and l-B=0.8.14
Moreover,
with surgical
hand disinfection
we
have repeatedly
demonstrated
the superior antibacterial activity
of alcoholic rubs over all other currently
available
methods
of pre-operative
hand
preparation.
As an example,
results from experiments with volunteers
as reported in the literature,
and in some of our own earlier publications,
are
given in Table II.
Using the method
of the European
prenorm
each
prEN 12791, 24 four surgical hand preparations,
applied for 3 min, were tested in our laboratory
in
five replications:
chlorhexidine
gluconate (4%) detergent, 70% (v/v) isopropanol,
85% (v/v) ethanol and
60% (v/v) n-propanol,
the latter being used as a reference. These hitherto unpublished
results demonstrate a clear rank in order of efficacy, mean log,, of
reduction
factors (mlr) were: chlorhexidine
soap,
(0.9) < 70% isopropanol
(mlr = 1.7) < 85% ethanol
(mlr = 2.2) <n-propanol
(mlr = 2.9).
The same ranks in order with comparable mlr was
found in a multi-centre
trial with five laboratories.
To demonstrate
a significant
difference
between
the reference disinfectant
and an (inferior)
other
product,
it was calculated
that a difference
of
approximately
0.7 mlr at OL (unidirectional)
= 0.1,
1 -B = 0.8 and employing
20 volunteers
was necessary (publication
in preparation).
From the results
reported
in the literature2’
and from the above
work, it is evident that the antibacterial
efficacy of
the three alcohols increases with concentration
and
S6
M. L. Rotter
Table II
Examples
fir
the efficacy
of various treatmentsin
reducing the resident flora from clean
hands*
Mean log,,, of reduction
Agent
Concentration
(%)
Immediate
factor
Sustained
(3 h)
Reference
Handwash
soap
Unmedicated
Povidone-iodine
liquid soap
Chlorhexidine
gluconate
(detergent)
Triclosan
(detergent)
0.8t
0.4
0.9-1.1
0.0-0. I
0.2-0.3
8, 18, I9
16, 18. l9,20
4.0t
0.9
0.6-0.9
16.19
I .ot
2.0t
0.6
0.8
0.5
I.1
I9
21
I .ot
1.9
0.8
8
2.0
1.5
I9
1.7
2. I-2.4
2.3-2.9
I .o
I B-2. I
1.6-1.8
I6
22
8.22.23
Handrub
Povidone-iodine
(aqueous)
Ethanol plus
Chlorhexidine
gluconate
Iso-propanol
77*+
0.5*
60$
70$
64
n-Propanol
*Duration
of all treatments:
5 min. twlv;
$v/v.
that the same rank in order exists between the alcohol species as found for hygienic hand disinfection.
In a separate experiment
it was shown with 60%
n-propanol
and 70% isopropanol,
applied for 1, 3
and Smin, that there is a clear and significant
association of the antibacterial
effect and the application time.22
Antimicrobial
spectrum
Alcohols exert a wide antimicrobial
spectrum including activity
against mycobacteria.
Mycobacterium
terrae which was chosen by the CEN TC 216 as an
non-pathogenic
surrogate for M. tuberculosis and has
been found as sensitive
to 60% isopropanol
as
Escherichia coli on the hands of volunteers
(unpublished). Likewise,
the fungicidal
activity
of shortchain, monovalent
alcohols, mainly ethanol, is well
recognised.26
Controversial
opinions
appear in the literature
on the antiviral
activity of alcohols. It is, however,
generally
agreed that lipophilic,
enveloped viruses
are easier to inactivate
than hydrophilic,
nonenveloped viruses, especially enteroviruses.26 Against
bacterial
spores, alcohols are generally
regarded
inactive,
at least for the short application
times
which are suitable for hand disinfection.
Skin acceptability
It should be noted that the addition
of suitable
emollients
has been shown to be of utmost importance: In a prospective,
randomized,
double-blind
trial, a mixture of 50% n-propanol
plus 30% isopropanol with and without emollients, was rubbed into
the hands
by two groups
of 10 volunteers,
15 times a day, five days a week, for 14 days.27 After
one week without
treatment,
each group
then
repeated the procedure using the converse preparation. At the end of each week, the hands were evaluated on a seven point scale (7 = best, 1 =worst)
for
their skin condition
with respect to ‘roughness’,
‘turgor’ and ‘sensation’ by self-assess‘reddening’,
ment and, with exception of the last criterion,
by a
dermatologist.
With both preparations,
only a slight
deterioration
of the skin condition was noticed after
14 days of use. Even this minor effect was significantly reduced when the test mixture
contained
emollients.
Examination
of silicone rubber templates of the
skin by computer-assisted
micro-image
analysis of
the shadows generated from the skin profile using
oblique
illumination
also revealed
a significant
impact on the skin condition of emollients contained
in alcoholic
rubs.28 Therefore,
alcoholic
solutions
Alcoholic
hand disinfection
s7
for frequent
hand disinfection
should never be
employed
without
emollients.
Practical experiences
in countries with cold and dry winters have taught
us that the acceptability
of alcoholic rubs is better
than that of frequent handwashing.
Economy
in time of application
Voss and Widmer3’
have shown that the length of
time necessary for an alcoholic rub is one-third
that
taken by a handwash procedure (including
the journey to and from a wash place). They suggested this
might improve
compliance
of medical staff with
the rules of hand hygiene. A significant
improvement of compliance
following
an intensive
campaign that included the change from handwashing
to alcoholic
rubs was recently
observed by Pittet
et .1.31a32 It remains to be seen how long the results
of these considerable
efforts will endure.
Disadvantages
of alcoholic
rubs
Some people find the smell of alcoholic hand-rubs
unpleasant.
Flammability
of alcohols is also of concern. A measure of the latter is the so-called flashpoint - the minimum
temperature
at which
a
flammable
substance can be ignited
by an open
flame. Short-chain
alcohols up to the propanols are
completely
miscible with water. In Table III, the
flash-points
of ethanol,
iso- and n-propanol
are
shown in relation to the concentration.
The higher
the concentration,
the lower the flash-point.
Liquids
with a flash-point
below 21°C are considered ‘easily
flammable’.
In most countries, there are more stringent regulations
for ‘easily flammable’
liquids with
regard to transportation
and storage than for ‘flammable’ liquids. The critical flash-point
of 21°C is
associated with respective concentrations
(by volume)
III Flash points of several concentrations
proponols assessed according to EN 22 7 I 9
Table
Flash-point
Concentration
(%) v/v
100
95
90
82
80
70
68
60
Ethanol
of ethanol
and the
of 82%, 70% and 60% for n-propanol,
iso-propanol
and ethanol. Therefore,
only ethanol is ‘easily flammable’ at concentrations
at which the antimicrobial
effect is sufficient,
i.e, at 77% and above. However,
flammability
can be decreased by mixing
ethanol
with n- or iso-propanol.
Furthermore,
ethanolic
hand-rubs
constitute
only a remote fire-hazard
if
contained in small-volume
dispensers.
In summary,
alcoholic
rubs have many advantages and only a few, but acceptable, disadvantages
compared with other hand disinfectants.
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