ASTM E2361-13(2021)
(Guide)Standard Guide for Testing Leave-On Products Using In-Situ Methods
Standard Guide for Testing Leave-On Products Using In-Situ Methods
SIGNIFICANCE AND USE
4.1 The United States has concentrated attention and testing efforts on surgical scrubbing far more than on hand care in patient-to-patient routines. Great Britain, the originators of infection control nursing, have always had their focus on infection transmission. In the United States, published articles have documented the short exposure time for health care personnel who do wash their hands between patients. The average is less than 10 s. The ideal product for the reduction of transient flora is one that rapidly kills or removes or both the microbial load acquired during health care activities. The emphasis on rapidity is essential simply because health care personnel will not take the necessary time when using conventional hand-washing products. The use of products not intended for use with water has increased dramatically and their use is common in European countries largely because of convenience and effectiveness. A second characteristic is the level of antimicrobial action. The use of a rapid and potent active product to reduce work-acquired microbial flora is ideal.
4.2 Since the change from strictly in-vitro testing of topical antimicrobials for use on skin to simulated use testing in hand washing, prepping, site access testing, and sampling, emphasis has always been on washing hands, agitating, rubbing, and brushing with liquid on the skin site to estimate bacteria removed after testing.
4.3 The use of hard agitation has diminished with surgical scrubs without brushes or with only mild agitation and friction.
4.4 There is a history of microbial dispersal (9) and increase in surface bacteria from deeper layers resulting from showering (10-12), washing, scrubbing, and agitation. In the normal situation on the skin, there is a superficial, surface flora and a deeper or hidden flora (5). The proportion of one to the other has been addressed by Selwyn (4) and his judgment is that from 20 to 50 % of the flora is “deep.” The intent in skin sampling has...
SCOPE
1.1 This guide covers test methods and sampling procedure options for leave-on products for consumer and hospital personnel. Leave-on products, such as alcohol hand rubs and lotions containing antimicrobial ingredients, are increasingly marketed and used by consumers and health care personnel. These products are distinguished from conventional washing and scrubbing preparations in that they do not rely on the rinsing, physical removal, and antimicrobial action in determining their effectiveness. Although agitation and friction may serve to release organisms from the skin and folds and crevices, organisms are then killed in situ and are not rinsed from the skin surface before sampling. Appropriate test methods for the hands have been published, while other sampling methods will be needed for testing body areas other than the hands.
1.1.1 Researchers have described techniques to identify the expanded flora we now know can be present on the skin. It is impractical, if not prohibitive to attempt to recover and identify these varieties of organisms with each test. At some point in the design of a test, a decision is necessary for defining the target organisms. Should the sampling be designed to recover as much of the microflora as possible or a particular portion of it? Consideration of transient and resident, superficial and deep, or aerobic and anaerobic flora must be included in defining the objective in testing products. The recovery methods selected for any testing must be based on the projected use of the product type being tested.
1.2 Methods of recovery after application of the contaminating organisms to a part of the body other than by the agitation/rubbing of the hands against a glass petri plate also need examination. Consideration should be given to contact plating, controlled swabbing with a template, and cup scrubbing (detergent/agitation used) since the target organisms for recovery are likely to be on th...
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2361 − 13 (Reapproved 2021)
Standard Guide for
Testing Leave-On Products Using In-Situ Methods
This standard is issued under the fixed designation E2361; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This guide covers test methods and sampling procedure
responsibility of the user of this standard to establish appro-
options for leave-on products for consumer and hospital
priate safety, health, and environmental practices and deter-
personnel. Leave-on products, such as alcohol hand rubs and
mine the applicability of regulatory limitations prior to use.
lotions containing antimicrobial ingredients, are increasingly
1.5 This international standard was developed in accor-
marketed and used by consumers and health care personnel.
dance with internationally recognized principles on standard-
These products are distinguished from conventional washing
and scrubbing preparations in that they do not rely on the ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
rinsing, physical removal, and antimicrobial action in deter-
mining their effectiveness.Although agitation and friction may mendations issued by the World Trade Organization Technical
servetoreleaseorganismsfromtheskinandfoldsandcrevices, Barriers to Trade (TBT) Committee.
organisms are then killed in situ and are not rinsed from the
skin surface before sampling.Appropriate test methods for the 2. Referenced Documents
hands have been published, while other sampling methods will
2.1 ASTM Standards:
be needed for testing body areas other than the hands.
E1174 Test Method for Evaluation of the Effectiveness of
1.1.1 Researchers have described techniques to identify the
Health Care Personnel Handwash Formulations
expanded flora we now know can be present on the skin. It is
E1327 Test Method for Evaluation of Antimicrobial Hand-
impractical,ifnotprohibitivetoattempttorecoverandidentify
wash Formulations by Utilizing Fingernail Regions
thesevarietiesoforganismswitheachtest.Atsomepointinthe
E2755 Test Method for Determining the Bacteria-
design of a test, a decision is necessary for defining the target
Eliminating Effectiveness of Healthcare Personnel Hand
organisms. Should the sampling be designed to recover as
Rub Formulations Using Hands of Adults
much of the microflora as possible or a particular portion of it?
Considerationoftransientandresident,superficialanddeep,or
2.2 European Standard:
aerobic and anaerobic flora must be included in defining the EN1500 Chemical Disinfectants and Antiseptics-Hygienic
objective in testing products. The recovery methods selected
Handrub-Test Method Requirements (phase 2/step 2)
for any testing must be based on the projected use of the approved by CEN (Comité Européen de Normalisation)
product type being tested.
3. Summary of Guide
1.2 Methods of recovery after application of the contami-
nating organisms to a part of the body other than by the
3.1 In this guide, choices of recovery techniques after the
agitation/rubbing of the hands against a glass petri plate also
use of antimicrobial products will be considered. By the nature
need examination. Consideration should be given to contact
of the distribution of the skin flora, these sampling techniques
plating, controlled swabbing with a template, and cup scrub-
estimate the flora remaining after antimicrobial use; some of it
bing (detergent/agitation used) since the target organisms for
is superficial and some hidden. An appropriate sampling
recovery are likely to be on the superficial layers of skin.
method can be selected depending on product use and the
1.3 The values stated in SI units are to be regarded as importance of superficial (transient) and hidden or deep
(mostly resident) flora. Recent publications have revealed a
standard. No other units of measurement are included in this
standard.
1 2
This guide is under the jurisdiction of ASTM Committee E35 on Pesticides, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Antimicrobials, and Alternative Control Agents and is the direct responsibility of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Subcommittee E35.15 on Antimicrobial Agents. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 15, 2021. Published October 2021. Originally the ASTM website.
approved in 2004. Last previous edition approved in 2013 as E2361 –13. DOI: Available from British Standards Institute (BSI), 389 Chiswick High Rd.,
10.1520/E2361-13R21. London W4 4AL, U.K.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2361 − 13 (2021)
greater variety of organisms that populate the skin and com- sampling by washing target organisms off with detergent,
prise the skin microbiome (1, 2). This information requires a assuming that most of removal is transient flora, and (2)
larger selection of recovery media. For certain applications, sampling in situ, for example, the cup scrub, swab, contact
such as acne studies or when recovery of the greatest diversity plate, or velvet block/pad that sample bacteria by impression
of organisms is desired, specific anaerobic/microaerophilic and contact or by using fluid to remove samples so that the
media should be used. volume of the sample is restricted to a very small size. These
different sampling methods disturb the deep or hidden flora to
3.2 This guide was originally written because ASTM Sub-
differing degrees. There has been an overwhelming concentra-
committee E35.15 worked on its own test method for leave-on
tion of the cup-scrub sampling method as various test methods
products used without water, but found that the EN1500
have been developed. The combination of detergent and
protocol encompassed the test method that had been devel-
agitation attempts to remove as much remaining flora as
oped. In 2010, a new standard test method specifically de-
possible.The best effort, however, only removes about 15 % of
signed to evaluate the efficacy of leave-on product was
the full thickness flora (4). When other contact sampling or
approvedunderthedesignationTestMethodE2755.Thisguide
tape stripping are used, the distribution of bacterial colonies on
has now been updated to cover Test Method E2755.
the skin are mirrored as they occur; whereas, if detergent/
3.3 ASTM has Test Method E1174 to test water-aided
scrubbing techniques are used, the microcolonies are dispersed
handwash products for health-care personnel. This test method
yielding higher counts. Washing/scrubbing methods stir up the
includes both wash-off and leave-on products. It has been
cells and bacteria from the deeper skin layers and release more
revised (E1174–13) to include special instructions for leave-on
of the hidden flora (described by Reybrouck (5)). This is also
products to use another Test Method E2755(–11) that has been
true of the cup scrub method that uses detergent/surfactants to
published for testing leave-on hand treatment products.
detach bacteria from the skin. Contact methods sample the
flora that can easily be transferred and that is conceded to be
3.4 This CEN type of test methodology is widely used in
European and Scandinavian countries but has not been widely the most important in disease transmission. Williams (6) has
stated that, “although the distinction between residents and
used in the United States, although the use of alcohol/alcohol
gel hand rubs has expanded greatly here in the last few years. transients must certainly be a real one, it is not to allocate the
various bacterial species to one or other class with regularity.”
The underlying question is whether a test method designed for
a leave-on product like alcohol or the conventional hand
3.7 There has been a long-time focus on the cup-scrub
washingfollowedbysamplinginagloveorplasticbagismore
technique only, and it would be beneficial to look at sampling
appropriate. There have been criticisms of test methods, such
specific areas, such as Test Method E1327, which samples
as EN1500, which was based on Rotter’s methods (3), but
around the fingernail region using a toothbrush, or the use of
published data confirm that the test is highly reliable in
direct contact plating when washing is not involved (7),asin
showing consistent reduction levels with low variation from
skin prepared for surgery. This guide is intended to assess the
subject to subject. Leave-on products that are not rinsed or
effectiveness of application of products rubbed into the skin or
washed off in use are primarily represented by alcohol-based
on the hands when these sites are not washed between uses.
hand rubs. However, other leave-on formulations have been
3.8 Superficially, the testing method is the same as with
introduced and, undoubtedly, their number will increase in the
products that are used to scrub and wash the hands or skin in
future. Often test methods designed for washing/rinsing pro-
that the hands are contaminated with a recoverable transient
cedures have been used for these products. When different
organismandthetestproductapplied.Thesimilarityendshere.
more specific methods are required for testing, questions of
methodology become clearer, and the selection of a new or
3.9 If the hands are sampled after application of organisms
different sampling method is necessary.
and the test product in sequence, they are dried or gloved wet
and are sampled after extensive rinsing. The stripping solution
3.5 When a typical hand-washing product is used, the hands
is then added for sampling to increase the release of viable
are wet; scrubbing and manipulation are pursued, often vigor-
organisms to be recovered. In contrast, in testing for hand rubs
ously; and rinsing follows. Agitation here is to remove organ-
or leave-on products, glove sampling would seem appropriate
isms and particulate and oily soil physically. Any residue of
only if sampling were performed after each contamination and
active ingredient remaining on the skin is a small fraction of
product application. Since changes have been made in Test
the amount applied and assumed to be attached to the stratum
Method E1327 to sample only after the first and last
corneum. The residual may also be absorbed over time.
applications, the applicability of this test method for products
Ultimately, the reduction in microbial count is a combination
rubbedintotheskinandusedrepeatedlywithoutwatermaynot
of kill from the antimicrobial and the physical removal by
be applicable for these leave-on products.
agitation and rinsing.
3.10 EN1500 is an adaptation of a test developed by Rotter
3.6 In contrast, leave-on products, such as alcohol products
known as the Vienna Model (8).
intended to be applied and not rinsed off, present a different
situation.There are two distinct techniques when sampling: (1)
3.11 There are many publications describing and evaluating
fingertip-sampling methods. One of the major criticisms of the
methods is the procedure used for sampling. The tips of the
fingers and thumb are sampled by rubbing against the bottom
The boldface numbers in parentheses refer to the list of references at the end of
this standard. of a glass petri dish to release contaminating bacteria from
E2361 − 13 (2021)
these areas before and after treatment. The sampled areas are methodology, Test Method E1174, which was originally de-
only portions of the areas treated. However, published results signed to test water-aided handwash products.
have shown consistent, statistically valid data. With the
5.1.2 Test Method E1174 measures the reduction of a
EN1500 test procedure, sampling is performed after a single
transient marker organism (Serratia marcescens) introduced to
use of the product (divided into two portions for application).
the hands in the form of a 24 h saturated liquid broth culture
(4.5 mL total). Hands are sampled via the glove juice proce-
4. Significance and Use
dure. Test products are evaluated after a single application and
after ten consecutive hand contamination and product applica-
4.1 The United States has concentrated attention and testing
tion cycles. The method presents several technical issues when
efforts on surgical scrubbing far more than on hand care in
evaluating leave-on products. The large volume of challenge
patient-to-patient routines. Great Britain, the originators of
organism often remains wet on the hands when the test product
infection control nursing, have always had their focus on
is applied thus diluting the active ingredient and leading to
infection transmission. In the United States, published articles
excessive product rub in times. Hand wetness is exacerbated
have documented the short exposure time for health care
over the course of the study and can result in a decline in
personnel who do wash their hands between patients. The
product efficacy over multiple application cycles.Additionally,
average is less than 10 s.The ideal product for the reduction of
the high soil load present in the challenge suspension can
transient flora is one that rapidly kills or removes or both the
further compromise the activity of the ABHR which are
microbial load acquired during health care activities. The
intended to be applied to dry, unsoiled hands.
emphasis on rapidity is essential simply because health care
5.1.3 In2010,ASTMInternationalapprovedanewstandard
personnel will not take the necessary time when using conven-
test method specifically developed to evaluate ABHR and to
tional hand-washing products. The use of products not in-
more closely estimate the in use conditions of leave-on
tended for use with water has increased dramatically and their
products (that is, dry hands which are minimally soiled). This
use is common in European countries largely because of
method, designated E2755, follows the same overall design of
convenience and effectiveness. A second characteristic is the
Test Method E1174 with the exception that hands are contami-
level of antimicrobial action. The use of a rapid and potent
nated with a greatly reduced volume of a concentrated chal-
active product to reduce work-acquired microbial
...
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