ASTM E2315-03(2008)
(Guide)Standard Guide for Assessment of Antimicrobial Activity Using a Time-Kill Procedure
Standard Guide for Assessment of Antimicrobial Activity Using a Time-Kill Procedure
SIGNIFICANCE AND USE
This procedure may be used to assess the in vitro reduction of a microbial population of test organisms after exposure to a test material.
SCOPE
1.1 This guide covers examples of a basic method to measure the changes of a population of aerobic microorganisms within a specified sampling time when tested against antimicrobial test materials in vitro. Several options for organism selection and growth, inoculum preparation, sampling times and temperatures are provided. When the basic technique is performed as a specific test method it is critical when evaluating the results to ensure that such variables have been standardized. Antimicrobial activity of specific materials, as measured by this technique, may vary significantly depending on variables selected. It is important to understand the limitations of in vitro tests, especially comparisons of results from tests performed under different circumstances. As an example, test results of microorganisms requiring growth supplements, or special incubation conditions, may not be directly comparable to more robust organisms under the conditions of a single procedure.
1.2 Knowledge of microbiological techniques is required for this test.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.
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Designation: E2315 − 03(Reapproved 2008)
Standard Guide for
Assessment of Antimicrobial Activity Using a Time-Kill
1
Procedure
This standard is issued under the fixed designation E2315; 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 E1054 Test Methods for Evaluation of Inactivators of Anti-
microbial Agents
1.1 This guide covers examples of a basic method to
measure the changes of a population of aerobic microorgan-
3. Terminology
isms within a specified sampling time when tested against
3.1 Definitions:
antimicrobial test materials in vitro. Several options for organ-
3.1.1 inoculum suspension, n—the initial suspension of test
ism selection and growth, inoculum preparation, sampling
organism used to inoculate the test material This may also be
timesandtemperaturesareprovided.Whenthebasictechnique
known as the organism inoculum (see 8.2).
is performed as a specific test method it is critical when
evaluating the results to ensure that such variables have been
3.1.2 microbial population, n—the microbial count (cfu/
standardized. Antimicrobial activity of specific materials, as
mL)inthefinalvolumeoftestmaterial(see9.4).Thismayalso
measured by this technique, may vary significantly depending
be known as the “initial population” or “numbers control.”
on variables selected. It is important to understand the limita-
3.1.3 neutralization, n—a process which results in the inac-
tions of in vitro tests, especially comparisons of results from
tivation or quenching of the antimicrobial activity of a test
tests performed under different circumstances.As an example,
material. This may be achieved through dilution of the test
test results of microorganisms requiring growth supplements,
material(s) or with the use of chemical agents, called
or special incubation conditions, may not be directly compa-
neutralizers, to reduce or quench the antimicrobial activity.
rable to more robust organisms under the conditions of a single
3.1.4 neutralizer, n—a procedure or chemical agent used to
procedure.
inactivate,neutralize,orquenchthemicrobiocidalpropertiesof
1.2 Knowledge of microbiological techniques is required
an antimicrobial agent.
for this test.
3.1.5 total test volume, n—the volume of test material plus
1.3 The values stated in SI units are to be regarded as
the volume of inoculum suspension.
standard. No other units of measurement are included in this
standard.
4. Summary of a Basic Test Method
1.4 This standard may involve hazardous materials, opera-
4.1 The test material or a dilution of the test material is
tions and equipment. This standard does not purport to address
brought into contact with a known population of microorgan-
all of the safety concerns, if any, associated with its use. It is
isms for a specified period of time at a specified temperature.
the responsibility of the user of this standard to establish
The activity of the test material is quenched at specified
appropriate safety and health practices and determine the
sampling intervals (for example, 30 s, 60 s, or any range
applicability of regulatory requirements prior to use.
covering several minutes or hours) with an appropriate neu-
tralization technique. The test material is neutralized at the
2. Referenced Documents
sampling time and the surviving microorganisms enumerated.
2
2.1 ASTM Standards:
The percent or log reduction, or both, from either an initial
10
D1193 Specification for Reagent Water
microbial population, or test blank is calculated.
1
This guide is under the jurisdiction of ASTM Committee E35 on Pesticides,
5. Significance and Use
Antimicrobials, and Alternative Control Agentsand is the direct responsibility of
Subcommittee E35.15 on Antimicrobial Agents.
5.1 This procedure may be used to assess the in vitro
Current edition approved April 1, 2008. Published May 2008. Originally
reduction of a microbial population of test organisms after
approved in 2003. Last previous edition approved in 2003 as E2315 – 03. DOI:
exposure to a test material.
10.1520/E2315-03R08.
2
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
6. Apparatus
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.1 Sterile Vials or Test Tubes, or equivalent.
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E2315 − 03 (2008)
6.2 Timer (Stop-clock), one that displays minutes and sec- 8.1.2.1 Alternativ
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