ASTM E3151-18

Standard Test Method for Determining Antimicrobial Activity and Biofilm Resistance Properties of Tube, Yarn, or Fiber Specimens

SIGNIFICANCE AND USE
5.1 Although a number of standardized tests currently exist for assessing the antimicrobial activity of treated polymers and textiles, these are optimized for specimens that readily absorb the test inoculum or that have a flat surface on which the inoculum can be placed, and their use for specimens with tubular geometries or for small quantities (less than 0.5 g) of yarns or fibers requires significant manipulation of the specimen.  
5.2 To adapt these methods for evaluating tubes, fiber, and yarn specimens requires distorting tubular specimens to create a flat surface or using unacceptably large quantities of fiber or yarn specimens. Rendering a test specimen having tubular geometry to a flat surface will limit its surface area available for exposure during the test and may require dissection of the specimen, which unacceptably alters it from its original state. Testing of treated fiber and yarn specimens using available standardized methods typically requires large quantities of material (greater than 0.5 g) that may not be available. In both cases, such manipulations may result in misleading results that do not reflect the antimicrobial efficacy of an unmodified specimen.  
5.3 This method provides an environment in which the inoculum remains in intimate contact with the surfaces of these types of test specimens, exposing both the intra- and extraluminal surfaces of tubular specimens without significant modification, and requiring only small quantities of fibers or yarns to perform testing.  
5.4 Classical antimicrobial test methods generally quantify the population or concentration of microorganisms that survive exposure to specimens treated with an antimicrobial agent without distinguishing whether the surviving microorganisms were in a planktonic or adhered/biofilm state.  
5.4.1 The phenotypic behavior of bacteria in the biofilm state differs substantially from when they are in the planktonic state, especially with respect to susceptibility to disinfectan...
SCOPE
1.1 This test method is designed as an in vitro, quantitative assay to evaluate the antimicrobial activity of specimens with tubular geometries or small segments of yarn or fibers that have been treated with an antimicrobial agent. Further, the method was designed to provide a quantitative assessment of a specimen’s ability to resist microbial colonization and subsequent biofilm formation relative to an untreated control specimen.  
1.1.1 The difference in number between the planktonic microbial population recovered from the treated test specimen and the population recovered from the control test specimen is the measure of the antimicrobial activity.  
1.1.2 The measure of the ability of the treated test specimen to resist biofilm development is the difference between the adherent microbial population recovered from the treated test specimen and the adherent microbial population recovered from the control test specimen.  
1.2 Testing is to be performed by individuals trained in microbiological techniques under appropriately controlled conditions to ensure the integrity of results and personnel safety.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-Jan-2018
• ICS: 59.080.20 - Yarns
• ICS: 59.080.80 - Smart textiles
• Technical Committee: E35 - Pesticides, Antimicrobials, and Alternative Control Agents
• Drafting Committee: E35.15 - Antimicrobial Agents

Relations

• Refers: ASTM E2756-19 - Standard Terminology Relating to Antimicrobial and Antiviral Agents
• Effective Date: 01-Nov-2019
• Refers: ASTM E2756-18 - Standard Terminology Relating to Antimicrobial and Antiviral Agents
• Effective Date: 01-Apr-2018
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E2756-10 - Standard Terminology Relating to Antimicrobial and Antiviral Agents
• Effective Date: 01-May-2010
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E1054-08 - Standard Test Methods for Evaluation of Inactivators of Antimicrobial Agents
• Effective Date: 01-Apr-2008
• Refers: ASTM E177-06b - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 15-Nov-2006
• Refers: ASTM E177-06a - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2006
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM E177-04 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004

Overview

ASTM E3151-18 is the international standard test method for determining the antimicrobial activity and biofilm resistance properties of tube, yarn, or fiber specimens that have been treated with antimicrobial agents. Developed by ASTM International, this standard is crucial for evaluating materials with complex or non-flat geometries, such as medical tubes, sutures, and technical fibers, that may not be adequately assessed by traditional antimicrobial tests.

Unlike test methods designed for flat surfaces or absorbent materials, ASTM E3151-18 enables accurate, quantitative assessment of antimicrobial activity and resistance to microbial colonization and biofilm formation in small quantities (less than 0.5g) or specimens with tubular geometries-without the need for distorting or altering the original state of the sample.

Key Topics

• Antimicrobial Activity: This method measures the reduction in planktonic (free-floating) microorganisms after exposure to the treated specimen, compared to an untreated control. Results are expressed as either log or percent reduction values.
• Biofilm Resistance: The standard quantitatively determines the ability of a specimen’s surface to resist microbial colonization, specifically biofilm formation, by comparing the number of adhered microorganisms on treated versus control samples.
• Suitable Specimens: Intended for tubes, yarns, and fibers, especially where other standardized tests are impractical or require substantial manipulation or large amounts of material.
• Testing Controls and Safety: Testing must be performed by trained professionals under controlled microbiological laboratory conditions, adhering to all relevant safety, health, and environmental regulations.
• Reporting Requirements: Reports must include all test parameters, any modifications to the protocol, and key data such as bacterial titers, control measures, and calculation methods for both antimicrobial and biofilm resistance assessments.

Applications

ASTM E3151-18 is especially valuable for manufacturers and laboratories in the following areas:

• Medical Devices: Assessment of antimicrobial properties in catheters, medical tubing, and surgical sutures, where contamination and biofilm formation are critical safety concerns.
• Textiles and Advanced Fibers: Evaluation of specialty yarns and fibers for medical or industrial applications that require precise antimicrobial performance.
• Small Quantity or Prototype Testing: When only small segments or limited amounts of test material are available, this method enables valid and reproducible results.
• Product Development and Quality Assurance: Aids in the research, development, and quality verification of antimicrobial treatments for fiber-based and tubular materials.
• Regulatory Compliance: Supports manufacturers in demonstrating antimicrobial efficacy and biofilm resistance as part of regulatory submissions or product claims.

Related Standards

For comprehensive antimicrobial testing and terminology, the following ASTM standards are closely related to ASTM E3151-18:

• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• ASTM E1054: Test Methods for Evaluation of Inactivators of Antimicrobial Agents
• ASTM E2756: Terminology Relating to Antimicrobial and Antiviral Agents

Conclusion

By providing a quantitative, reproducible approach for assessing antimicrobial and biofilm resistance properties in tubes, yarns, and fibers, ASTM E3151-18 addresses a significant testing gap in the textile, polymer, and medical device industries. It ensures that antimicrobial treatments are measured accurately under conditions that closely simulate their intended real-world use, facilitating safer, more effective products and supporting global regulatory requirements.

Keywords: ASTM E3151-18, antimicrobial activity, biofilm resistance, tube specimens, yarn, fiber, testing standard, medical device, textile, quality assurance, microbial colonization, planktonic bacteria, international standard.

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:E3151 −18
Standard Test Method for
Determining Antimicrobial Activity and Biofilm Resistance
Properties of Tube, Yarn, or Fiber Specimens
This standard is issued under the fixed designation E3151; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method is designed as an in vitro, quantitative 2.1 ASTM Standards:
assay to evaluate the antimicrobial activity of specimens with E177Practice for Use of the Terms Precision and Bias in
tubulargeometriesorsmallsegmentsofyarnorfibersthathave ASTM Test Methods
been treated with an antimicrobial agent. Further, the method E691Practice for Conducting an Interlaboratory Study to
was designed to provide a quantitative assessment of a speci- Determine the Precision of a Test Method
men’s ability to resist microbial colonization and subsequent E1054Test Methods for Evaluation of Inactivators of Anti-
biofilm formation relative to an untreated control specimen. microbial Agents
1.1.1 The difference in number between the planktonic E2756Terminology Relating toAntimicrobial andAntiviral
microbial population recovered from the treated test specimen Agents
and the population recovered from the control test specimen is
3. Terminology
the measure of the antimicrobial activity.
1.1.2 Themeasureoftheabilityofthetreatedtestspecimen 3.1 Fordefinitionsoftermsusedinthistestmethod,referto
to resist biofilm development is the difference between the Terminology E2756.
adherent microbial population recovered from the treated test
4. Summary of Test Method
specimen and the adherent microbial population recovered
from the control test specimen. 4.1 The control and treated test specimens are placed into
individual6×50mm culture tubes containing suspensions of
1.2 Testing is to be performed by individuals trained in
a known biofilm-producing strain of Staphylococcus epider-
microbiologicaltechniquesunderappropriatelycontrolledcon-
midis (ATCC 35984 ) at a specific titer and incubated at 35 6
ditions to ensure the integrity of results and personnel safety.
2°C with mild agitation for 24 62h.
1.3 The values stated in SI units are to be regarded as
4.2 After the contact time, each specimen is transferred to
standard. No other units of measurement are included in this
an individual centrifuge tube containing a sterile buffered
standard.
saline rinse solution, and the tube is sealed and carefully
1.4 This standard may involve hazardous materials,
inverted several times to remove any non-adhered or loosely
operations, and equipment. This standard does not purport to
adhered bacteria.
address all of the safety concerns, if any, associated with its
4.3 The specimens are then transferred to new centrifuge
use. It is the responsibility of the user of this standard to
tubescontaininglowconcentrationsofasurfactantdispersedin
establish appropriate safety, health, and environmental prac-
a neutralizing agent demonstrated to deactivate the antimicro-
tices and determine the applicability of regulatory limitations
bial agent with which the test specimen is treated.
prior to use.
1.5 This international standard was developed in accor-
4.4 These tubes are sealed, vortexed, and sonicated to
dance with internationally recognized principles on standard-
suspend any bacteria adhered to the surface of the specimens
ization established in the Decision on Principles for the
and to disaggregate any biofilm clumps present.
Development of International Standards, Guides and Recom-
4.5 The population of planktonic bacteria within the test
mendations issued by the World Trade Organization Technical
inoculum exposed to each test specimen and the re-suspended
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee E35 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Pesticides, Antimicrobials, and Alternative Control Agents and is the direct Standards volume information, refer to the standard’s Document Summary page on
responsibility of Subcommittee E35.15 on Antimicrobial Agents. the ASTM website.
Current edition approved Feb. 1, 2018. Published May 2018. DOI: 10.1520/ ATCC is a registered trademark andATCC 35984 is a trademark ofAmerican
E3151-18. Type Culture Collection, Manassas, VA.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3151−18
adherent bacteria harvested from the surface of each test appropriateness of this simulated environment relative to the
specimen are enumerated using standard microbiological tech- intended end-use of the test material should be evaluated prior
niques. to testing.
4.6 The efficacy of the antimicrobial treatment versus the 5.6 Although this method is designed to provide an initial
planktonic bacteria recovered in the neutralized inocula sus- assessmentoftheantimicrobialactivityexhibitedbyamaterial
pensionandtheadherentbacteriarecoveredfromthesurfaceof and its ability to resist microbial colonization under very
the specimens is the percent and log reductions calculated as specific test parameters, these conditions may not be represen-
thedifferencebetweenpopulationsfromtreatedspecimensand tative of all environments to which the specimen may be
those from the controls. exposed during its intended end-use. Various test parameters
specified in this method can be modified to evaluate a material
5. Significance and Use
under conditions that may better simulate end-use
environments, but such alterations of the method must be
5.1 Although a number of standardized tests currently exist
clearly described when reporting results.
forassessingtheantimicrobialactivityoftreatedpolymersand
textiles, these are optimized for specimens that readily absorb
6. Apparatus
the test inoculum or that have a flat surface on which the
inoculum can be placed, and their use for specimens with
6.1 Autoclave (steam sterilizer), any suitable for processing
tubular geometries or for small quantities (less than 0.5 g) of
culture media, reagents, and labware.
yarns or fibers requires significant manipulation of the speci-
6.2 Biological safety cabinet.
men.
6.3 Incubator, any capable of maintaining a temperature of
5.2 To adapt these methods for evaluating tubes, fiber, and
35 6 2°C.
yarn specimens requires distorting tubular specimens to create
a flat surface or using unacceptably large quantities of fiber or 6.4 pH meter, any capable of measuring to 0.2 units.
yarn specimens. Rendering a test specimen having tubular
6.5 Vortex mixer.
geometry to a flat surface will limit its surface area available
6.6 Orbital shaker,anycapableofmaintaining100rotations
for exposure during the test and may require dissection of the
per minute (rpm).
specimen, which unacceptably alters it from its original state.
Testing of treated fiber and yarn specimens using available 6.7 Refrigerator, any capable of maintaining 4 6 2°C for
standardized methods typically requires large quantities of
storage of media, culture plates, and reagents.
material (greater than 0.5 g) that may not be available. In both
6.8 Ultrasonic cleaner, any capable of a watt density output
cases, such manipulations may result in misleading results that
of100to133wattspergallonatafrequencyof42kHz 66%.
do not reflect the antimicrobial efficacy of an unmodified
6.9 Timer (stopwatch),onethatdisplayshours,minutes,and
specimen.
seconds.
5.3 This method provides an environment in which the
6.10 Dissecting forceps, fine tip.
inoculumremainsinintimatecontactwiththesurfacesofthese
types of test specimens, exposing both the intra- and extralu- 6.11 Scissors or Razor blade.
minal surfaces of tubular specimens without significant
6.12 Pipette pumps, 1- to 10-mL and 1- to 25-mL capacity.
modification, and requiring only small quantities of fibers or
6.13 Serological pipettes, sterile reusable or single-use pi-
yarns to perform testing.
pettes of 10.0- and 25-mL capacity.
5.4 Classical antimicrobial test methods generally quantify
6.14 Pipette and appropriate sterile pipette tips, variable
thepopulationorconcentrationofmicroorganismsthatsurvive
volume, positive displacement, 20- to 200-µL volume range.
exposure to specimens treated with an antimicrobial agent
without distinguishing whether the surviving microorganisms
6.15 Pipette and appropriate sterile pipette tips, variable
were in a planktonic or adhered/biofilm state.
volume,positivedisplacement,100-to1000-µLvolumerange.
5.4.1 The phenotypic behavior of bacteria in the biofilm
6.16 Petri dishes, sterile, 15 × 100 mm.
state differs substantially from when they are in the planktonic
6.17 Microcentrifuge tubes, sterile, 1.7 mL.
state, especially with respect to susceptibility to disinfectants,
sanitizers, and antimicrobial agents. Therefore, evaluating the
6.18 Centrifuge tubes with caps, sterile, 15 mL.
ability of a material’s surface to resist bacterial colonization
6.19 Centrifuge tubes with caps, sterile, 50 mL.
may be of equal or greater significance than its efficacy versus
6.20 Culture tubes, sterile,6×50mm.
planktonic bacteria.
5.4.2 This method not only can assess the population of the
6.21 Culture tubes and closures, sterile, any with a mini-
challenge species that survives planktonic exposure to the test
mumvolumecapacityof10mLandaminimumdiameterof16
specimen,butalsocanthencomparethattothepopulationthat
mm. Recommended size is 16 × 125-mm borosilicate glass.
survives in an adherent/biofilm state.
6.22 Inoculating loops, sterile, 4-mm ring diameter.
5.5 This test method is a batch-based system in which test
6.23 Water absorbent laboratory wipe, sterile.
specimens are exposed to a continuous, minimal fluid shear
environment in the presence of the challenge inoculum. The 6.24 Sealing film, paraffin or equivalent.
E3151−18
6.25 Dilution vessels. 9. Preparation of Bacterial Inoculum
9.1 Growafresh18-to24-hshakecultureof S. epidermidis
7. Reagents and Materials
(8.1)insterilebrothgrowthmedium(7.2.1)at35 62°Cprior
7.1 Reagent grade chemicals shall be used in all tests.
to performing the test.
Unlessotherwiseindicated,itisintendedthatallreagentsshall 9.1.1 Prepare these cultures from an 18- to 24-h growth
conform to the specifications of the committee on Analytical
from stock culture plates or agar slants.
Reagents of the American Chemical Society, where such
9.2 Dilute this stock suspension of bacteria appropriately
specifications are available. Other grades may be used, pro-
using inoculation medium (7.2.3) to achieve a final bacterial
vided it is pure enough to be used without lessening the 5
titerbetween1.0×10 colonyformingunits(CFU)/mLand5.0
accuracy of the determination. 5 5
×10 CFU/mL with the target being 3.0 × 10 CFU/mL.
7.2 Growth Media:
9.3 Centrifuge the diluted stock suspension to harvest the
7.2.1 Liquid Growth Medium, Tryptic Soy Broth (TSB),
bacterial cells.
sterile (See Annex A1).
9.3.1 Centrifuge for 5 min at 15294 × g.
7.2.2 Solid Growth and Plating Medium, Tryptic Soy Agar
9.4 Remove at least 90% of the resulting supernatant.
(TSA), sterile (See Annex A1).
7.2.3 Inoculation Medium, 1/500 Tryptic Soy Broth.
9.5 Reconstitute the pelletized cells in a volume of the
7.2.3.1 Asepticallyadd1.0mLofTSB(7.2.1)to499mLof
inoculation medium (7.2.3) equal to the volume of supernatant
distilled or deionized water (7.6).
removed.
7.2.3.2 Adjust the pH to a value between 6.8 and 7.2 using
9.5.1 This bacterial suspension is the test inoculum.
either sodium hydroxide or hydrochloric acid.
9.5.2 The test inoculum is to be used within2hof
7.2.3.3 Sterilize by autoclaving.
preparation.
7.2.3.4 Ifnotusedimmediatelyafterpreparation,theinocu-
9.6 Verify the titer of bacteria in the test inoculum by
lation medium can be stored at 4 6 2°C for no longer than 7
performing serial dilutions and utilizing a validated microbial
days.
enumeration technique (for example, pour plate, spread plate,
7.3 Phosphate Buffered Saline, sterile.
spiral plate, or membrane filtration).
9.6.1 Report the bacterial titer in the test inoculum in the
7.4 Neutralizing Solution, appropriate for neutralizing the
final report. If the bacterial titer of the test inoculum does not
activeantimicrobialagentinthetreatedtestspecimen(SeeTest
5 5
fall within the range of 1.0 × 10 CFU/mL to 5.0 × 10
Method E1054).
CFU/mL, the test is considered invalid and the specimen must
7.5 Modified Neutralizing Solution, Neutralizing Solution
be retested.
(7.4) with 1% by volume Polysorbate 80.
NOTE 3—Alternative inoculum bacterial titers and inoculum media can
7.6 Distilled or Deionized Water, sterile.
be substituted to better simulate the end-use conditions. If so, all
modifications must be documented in the test report and the test report
7.7 Dilution Fluid or Diluent, sterile water, sterile saline,
must indicate that ASTM Method E3151, modified, was used. The
sterile buffered phosphate diluents or equivalent.
precision statistics reported in this method will not apply.
NOTE 4—A nonionic surfactant may be added to the test inoculum to
8. Test Organism
improve the wetting of hydrophobic specimens. Surfactants should be
shown through prior testing not to cause a change in the bacterial
8.1 Staphylococcus epidermidis, American Type Culture
population at the intended use-concentration. If used, the chemical name
Collection (ATCC) No. 35984.
of the surfactant and its final concentration in the test inoculum must be
documented in the test report. The test report also must indicate that
8.2 Cultures of the test organism shall be maintained using
ASTM Method E3151, modified, was used. The precision statistics
appropriate microbiological practices.
reported in this method will not apply.
NOTE 5—In Steps 9.2 and 9.3, the stock suspension can be centrifuged
NOTE 1—To ensure the most consistent and accurate results, the purity
prior to dilution to the target bacterial titer. An alternative validated
oftheculturesshouldbecheckedregularlyusingstandardmicrobiological
approach for the harvesting of bacterial cells using centrifugation may be
speciation techniques.
used, but the conditions of use (relative centrifugal force and duration of
NOTE2—Additionalchallengespeciescanbesubstitutedtoevaluatethe
centrifugation) must be documented in the test report and the test report
breadth of a material’s antimicrobial activity versus species to which it
must indicate that ASTM Method E3151, modified, was used.
may be exposed. If an alternative challenge species is used in testing, it
must be identified in the final report, along with any accommodative
10. Test Specimen Preparation
modifications made to the method (that is, changes to culture media,
buffers, etc.). The test report also must indicate that ASTM Method
10.1 A non-treated control specimen of composition and
E3151, modified, was used. The precision statistics reported in this
construction closely similar to the antimicrobially treated
method will not apply.
specimen(s) must be evaluated at the same time and under the
same conditions as the treated specimen(s).
10.2 Cut test specimens of each sample being examined to
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
create segments 40 mm in length.
listed by the American Chemical Society, see Analar Standards for Laboratory
10.2.1 Prepare three replicate specimens of each treated
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
sample that is to be tested to help reduce variability in the test
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. results.
E3151−18
same number of segments of the non-treated control specimen and the
10.2.2 Prepare three replicate specimens of the non-treated
antimicrobially treated specimen must be tested.The number of segments
control sample for evaluation.
evaluated during testing must be documented in the test report.
10.2.3 When preparing the test specimens, take care to
NOTE 10—Various exposure periods may be used to evaluate the
avoid contamination with microorganisms or other contami-
activity of the treated test specimen at time points relevant to use patterns
nants that may impact the test results.
ofproductsinwhichthetreatedtestspecimenmaybeused.Theexposure
period used during testing must be documented in the test report.The test
10.2.4 When testing a specimen composed of absorbent
report also must indicate thatASTM Method E3151, modified, was used.
materials, the specimen must not absorb more than 0.2 mL of
The precision statistics reported in this method will not apply.
the challenge inoculum.
NOTE 6—This is to ensure that a volume of inoculum remains in the
12. Recovery of Planktonic Bacteria from Test Inocula
culture tube after the test specimen has been removed sufficient to
12.1 Following the exposure period, use sterilized forceps
determining the planktonic population that survived exposure.
totransfereachtestspecimenintoaseparate50-mLcentrifuge
10.2.5 Test specimens with a diameter greater than 3 mm
tube (6.19) containing 40 mL of sterile phosphate buffered
should not be examined using this test.
saline (7.3).
NOTE 7—This is to ensure the sample is of a size that can be easily
12.1.1 Immediately after removing tubular specimens from
placed into and removed from the6×50mm culture tube used to expose
the culture tubes, orient them above the culture tube such that
the test specimen to the inoculum.
theendofthespecimenisabovethemouthofthetube,anduse
NOTE 8—If necessary, specimens can be sterilized after being cut to
reduce the potential for contaminative microorganisms impacting the
apipettorwithasteriletiptoblowanyliquidwithinthelumen
resultsofthetest.Asterilizationtechniquethatdoesnotaffectthematerial
into the culture tube. This step is not necessary for yarn and
composition of the specimens must be used. If test specimens are
fiber specimens.
sterilized, the sterilization technique used must be documented in the test
12.1.2 Carefully tap the end of the test specimen onto a
report.
sterile laboratory wipe (6.23), or other sterile absorbent
11. Inoculation and Incubation of Test Specimen
material, to remove excess inoculum before transferring test
specimens to the 50-mL centrifuge tubes containing 40 mL of
11.1 For Tubular Specimens:
sterile phosphate buffered sa
...