ASTM E2314-03(2014)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E2314 − 03 (Reapproved 2014)
Standard Test Method for
Determination of Effectiveness of Cleaning Processes for
Reusable Medical Instruments Using a Microbiologic
Method (Simulated Use Test)
This standard is issued under the fixed designation E2314; 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.
INTRODUCTION
Cleaning is acknowledged as the critical first step in the reprocessing of reusable medical
instruments. A test method to examine the efficacy and reproducibility of cleaning procedures would
be valuable in optimizing decontamination of medical instruments, as well as increasing the margin
of safety of subsequent disinfection and sterilization procedures. This test method is a means of
determining the efficacy of the instrument manufacturer’s cleaning instructions. In this simulated use
test cleaning steps are performed with the instruments in a controlled laboratory environment. Within
this environment, various parameters may be exaggerated to create worst-case conditions for the test.
Among these are the amount or type of organic soil or microorganisms contaminating the instruments.
The test method was developed primarily for large medical instruments or instruments with internal
channels or recesses (for example, flexible endoscopes) but may be used for any resuable medical
instruments. It employs both direct inoculation and sampling methods for external surfaces and
indirect inoculation and sampling methods for less accessible internal channels.
Cleaning is defined as the removal of foreign materials, most often mixtures of organic soil (for
example, protein) and microorganisms, from medical instruments. Bacterial endospores are the
preferred microorganisms in this simulated test because they would be more resistant to the potential
microbiocidal effects of the cleaning processes and solutions. This method examines the reduction in
the number of spores as a tracer of foreign materials and not necessarily the reduction in organic soil
directly.
This test may be designed to either examine the efficacy of a complete cleaning cycle consisting of
several integrated steps or individual cleaning step such as precleaning, manual cleaning, automated
cleaning or rinsing.
1. Scope 1.3 The test method utilizes bacterial spores as tracers for
foreign materials and quantifies their removal as a means of
1.1 This test method is written principally for large medical
determining the efficacy of a cleaning process.
instruments or instruments with internal channels or recesses
1.4 The test method is designed for use by manufacturers of
(for example, flexible endoscopes) but may be used for any
medical instruments and devices. However, it may also be
resuable medical instruments.
employed by other individuals who have a knowledge of the
1.2 This test method describes a procedure for testing the
instruments, techniques and access to appropriate facilities.
efficacy of a cleaning process for reusable medical instruments
1.5 Worst-case conditions can be represented by exaggerat-
artificially contaminated with mixtures of microorganisms and
ing a specific test parameter or otherwise intentionally simu-
simulated soil.
latinganextremeconditionsuchasperformingthetestwithout
cleaning solutions or utilizing instruments which are not new.
1.6 The test procedure is devised to determine the efficacy
This test method is under the jurisdiction of ASTM Committee E35 on
of a cleaning process as applied to a particular instrument or
Pesticides, Antimicrobials, and Alternative Control Agentsand is the direct respon-
sibility of Subcommittee E35.15 on Antimicrobial Agents. group of instruments by simulating actual use situations.
Current edition approved Oct. 1, 2014. Published December 2014. Originally
1.7 The test procedure may be performed on test instru-
approved in 2003. Last previous edition approved in 2008 as E2314 – 03(2008).
DOI: 10.1520/E2314-03R14. ments using a complete cleaning cycle or be limited to
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2314 − 03 (2014)
particular phases of the cycle such as precleaning, manual 3.1.1 accessible location—a location on a reusable medical
cleaning, automated cleaning, or rinsing. instrument(s) that may be contacted by bioburden, soil and
cleaning agents.
1.8 The test procedure is normally performed on a number
of external and internal sites, but it may be restricted to one 3.1.2 automated cleaning—the removal of foreign material
particular site on the instrument. from medical instruments by means of a machine.
3.1.3 bioburden—the number and types of viable microor-
1.9 A knowledge of microbiological and aseptic techniques
and familiarity with the instruments is required to conduct ganisms that contaminate an instrument.
these procedures.
3.1.4 CFU—colony forming units.
NOTE 1—Because contamination of the surfaces of instruments may
3.1.5 cleaning—the removal of foreign materials, including
occur as a result of rinsing with tap water, bacteria-free water should be
used for all rinsing when a water rinse step is part of the cleaning
organic soil (for example, protein) and microorganisms from
directions.
medical instruments.
NOTE 2—Test methods to determine the effectiveness of cleaning
3.1.6 cleaning solution—a solution used to aid in the re-
medical instruments has only recently been actively debated, and research
efforts are in their infancy. Because published experimental results are
moval of foreign matter from medical instruments.
scarce, it is premature to dictate experimental reagents, conditions or
3.1.7 manual cleaning—the removal of foreign material
acceptance criteria.
NOTE 3—The total elimination of the target organisms is not the goal of from a medical instrument without the aid of a machine.
cleaning. Therefore, there will almost always be a number of microorgan-
3.2 Definitions of Terms Specific to This Standard:
isms surviving on the test instruments unless one of the solutions or
3.2.1 cleaning effıcacy—the efficacy of cleaning may be
processes disinfects or sterilizes the test instrument.The results of various
clinical and laboratory tests suggest that cleaning processes alone can
calculated as the log reduction of viable microorganisms
2 4
produce a 10 to 10 log reduction in bioburden. The exact reduction
10 recovered from the test instruments as compared to the control
will depend upon the precise experimental conditions. The criteria for
instruments.
judgingcleanlinessshouldbedeterminedandrecordedbeforeinitiationof
the test procedure.
3.2.2 control instruments—reusable medical instruments
NOTE 4—This test protocol employs target spores as indicators or
which are inoculated but not subjected to the Test Cycle.
tracers for foreign materials and monitors their removal by the cleaning
3.2.2.1 control instrument recovery—the quantity of inocu-
process. It is certainly possible that other particulate target materials, such
as microbeads (latex beads) could be used in place of microbes. These
lum that can be recovered from the accessible locations (for
alternate approaches would be more practical in those circumstances
example, external surface sites and lumens, if any) of the
where microbiological expertise is limited.
control instruments.
1.10 The values stated in SI units are to be regarded as
3.2.3 neutralizer—a reagent used to stop the antimicrobial
standard. No other units of measurement are included in this
activity of residual cleaning agent(s) that may be present on
standard.
test instruments and eluted along with the target microorgan-
1.11 This standard may involve hazardous materials,
isms. (See Practices E1054 for recommended neutralizers.)
operations, and equipment. This standard does not purport to
3.2.4 reusable medical instrument—any medical instrument
address all of the safety concerns, if any, associated with its
that is claimed by the manufacturer to be usable after repro-
use. It is the responsibility of the user of this standard to
cessing.
establish appropriate safety and health practices and deter-
3.2.5 test cycle—a cleaning process that utilizes all of the
mine the applicability of regulatory limitations prior to use.
parameters selected by the tester.
2. Referenced Documents
3.2.6 test instruments—reusable medical instruments which
2.1 ASTM Standards:
are inoculated and subjected to the Test Cycle. These instru-
D1193 Specification for Reagent Water
ments are used to determine the efficacy of the cleaning
E1054 Test Methods for Evaluation of Inactivators of Anti-
process.
microbial Agents
3.2.6.1 test instrument recovery—the quantity of inoculum
E1766 Test Method for Determination of Effectiveness of
that can be recovered from the accessible locations (for
Sterilization Processes for Reusable Medical Devices
example, external surface sites and lumens, if any) of the test
2.2 Other Source:
instruments.
AAMI, TIR No. 30 ACompendium of Processes, Materials,
Test Methods, and Acceptance Criteria for Cleaning Re-
3.2.7 test soil—a formulation of organic materials used in
usable Medical Devices testing the efficacy of cleaning.
3.2.8 worst-case—the intentional exaggeration of one or
3. Terminology
more parameters of a test compared to the normal condition.
3.1 Definitions:
For example, this could include exaggerated soil load or
deletion of cleaning steps.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4. Summary of Test Method
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
4.1 This test method is performed by inoculating interior or
Available from Association for the Advancement of Medical Instrumentation
(AAMI), 1110 North Glebe Road, Suite 220, Arlington, VA 22201-4795. exterior surfaces, or both, of reusable medical instruments.
E2314 − 03 (2014)
4.2 Both control instruments and test instruments are used 6.5 Sterile Bottles, to hold 50 mL and sterile flasks to hold
in this test method. Prior to inoculation, all instruments are 250 to 500 mL.
cleaned and reprocessed. An inoculum with high numbers of
6.6 Sterilization Device, for the medical instruments being
target microorganisms suspended in test soil is applied to both
examined. Alternatively, supplies for high level disinfection
control and test instruments.
recommended by the instrument manufacturer.
4.3 It is impractical to determine inoculum recovery by
6.7 Water Bath, which can maintain temperature from 20 to
immersion of large medical instruments or instruments with
50 6 2°C.
internal channels or recesses (for example, flexible endo-
6.8 Incubator(s), which maintain 37 6 2°C (for B.
scopes) in elution fluid because of their complexity, size, or
atrophaeus, formerly known as Bacillus subtilis subspecies
deleterious effects from immersion. Therefore, rinsing or
niger) or temperature appropriate for selected target organism.
swabbingtechniquesareusedtorecovertargetmicroorganisms
from these types of inoculated instruments.
6.9 Membrane Filters, 0.45 µm, and filter supports for the
filters.
4.4 Controlinstrumentsareusedtodeterminethenumberof
organisms which can be recovered from the instruments. At
6.10 Colony Counter.
least two control instruments are inoculated in the same
6.11 Disposable Plastic Pipettes, various sizes.
manner as the test instruments, however cleaning is not
performed. An appropriate recovery method (see 4.3) is then
6.12 Reusable Medical Instruments, reprocessed prior to
used to determine the level of inoculum recoverable from the
each use.
instruments. At least 10 CFU recoverable per instrument are
6.13 Cleaning Devices, accessories or apparatus to be used
required. For an instrument with lumens, the total number of
in the Test Cycle and/or for reprocessing between uses as
organisms recovered from both inside and outside surfaces of
specified by the manufacturer of the test instrument.
the instrument will be defined as the control instrument
6.14 Vortex Mixer and/or Sonicator.
recovery.
4.5 After the Test Cycle has been completed using the test 6.15 Vacuum Pump.
instruments, the inoculated target microorganisms remaining
6.16 Shaker and/or Stirrer.
on these instruments are recovered using the same elution,
recovery and quantitation procedures used to determine the
7. Reagents
number of target microorganisms on the control instruments.
7.1 Media:
By comparing this test instrument recovery to the control
7.1.1 Sterile USP Fluid D (Elution Fluid), containing poly-
instrument recovery, the efficacy of the cleaning process may
sorbate 80. Alternatively, sterile elution fluid solution contain-
be calculated.
ing 0.4 g KH PO , 10.1 g Na HPO , and 1.0 g isooctylphe-
2 4 2 4
5. Significance and Use noxypolyethoxy ethanol (Triton X-100) prepared in 1 L of
Type III or betterASTM water adjusted to pH 7.8. Neutralizers
5.1 This test method is designed to evaluate the effective-
appropriate for the cleaning solution may be added to either of
ness of cleaning reusable medical instruments using a specified
these solutions.
cleaning process.
7.1.2 Soybean-Casein Digest Broth, USP, with and without
5.2 This test method may be used to determine the effec-
appropriate neutralizers for the specific test cleaning chemi-
tivenessofcleaningprocessesofrecesses,hingedsites,lumina,
cal(s) in the cleaning solution.
or other difficult-to-reprocess areas of reusable medical instru-
7.1.3 Soybean-Casein Digest Agar, USP, single or double
ments.
strength with and without appropriate neutralizers in 10 to 50
5.3 This test method may also be used to verify the claims
mL tubes or bottles tempered to 48 6 2°C.
for any portion of the cleaning cycle.
7.1.4 Sterile Saline or Phosphate Buffer, for rinsing mem-
brane filters.
5.4 The recovery of surviving microorganisms may be
accomplished using swabbing, rinsing, or total immersion of
7.2 Target Organisms—Standardized suspensions of Bacil-
instruments.
lus atrophaeus endospores (ATCC 9372) containing nominally
10 CFU/mL should be used. Standardized bacterial spore
5.5 Theefficacyoftheelutionmethodsorlossoftheapplied
suspensions are commercially available. The origin of the
inoculum may be assessed by recovery of target organisms
spore strain, production, storage, and expiration dates should
from control instruments that have not been subjected to the
be identified. Bacterial endospores are preferred as the target
clean
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