ASTM E1326-06
(Guide)Standard Guide for Evaluating Nonconventional Microbiological Tests Used for Enumerating Bacteria
Standard Guide for Evaluating Nonconventional Microbiological Tests Used for Enumerating Bacteria
SIGNIFICANCE AND USE
This guide should be used by producers and potential producers of nonconventional tests to determine the accuracy, selectivity, specificity, and reproducibility of the tests, as defined in Practices E 691 and D 3870. Results of such studies should identify the limitations and indicate the utility or applicability of the nonconventional test, or both, for use on different types of samples.
Nonconventional test users and potential users should employ this guide to evaluate results of the nonconventional test as compared to their present methods. Practices D 5245 and D 5465 should be reviewed in regards to the conventional microbiological methods employed. If conventional methods have not been used for monitoring the systems, then guidelines are included for obtaining microbiological expertise.
Utilization of a nonconventional test may reduce the time required to determine the microbiological status of the system and enable an improvement in the overall operating efficiency. In many cases, the findings of a significantly high level of bacteria indicates the need for an addition of an antimicrobial agent. By accurately determining this in a shorter time period than by conventional methods, treatment with antimicrobial agents may circumvent more serious problems than if the treatment were postponed until conventional results were available. If the antimicrobial treatment program relies on an inaccurate nonconventional test, then unnecessary loss of product and problems associated with inappropriate selection or improper dosing with antimicrobial agents would exist.
Since many methods based on entirely different chemical and microbiological principles are considered, it is not possible to establish a unique design and recommend a specific method of statistical analyses for the comparisons to be made. It is only possible to present guides that should be followed while performing the experiments. It is also recommended that a statistician be involved in the study.
SCOPE
1.1 The purpose of this guide is to assist users and producers of nonconventional tests in determining the applicability of the test for processing different types of samples and evaluating the accuracy of the results. Conventional procedures such as the Heterotrophic (Standard) Plate Count, the Most Probable Number (MPN) method and the Spread Plate Count are widely cited and accepted for the enumeration of microorganisms. However, these methods have their limitations, such as performance time and degree of accuracy. It is these limitations that have recently led to the marketing of a variety of non-conventional procedures, test kits and instruments.
1.2 A conventional test is one that is widely accepted and published as a standard microbiological method or related procedure. A new, nonconventional test method will attempt to provide the same information through the measurement of a different parameter. This guide is designed to assist investigators in assessing the accuracy and precision of nonconventional methods intended for the determination of microbial population densities or activities.
1.3 It is recognized that the Heterotrophic Plate Count does not recover all microorganisms present in a product or a system (, ). When this problem occurs during the characterization of a microbiological population, alternative standard enumeration procedures may be necessary, as in the case of sulfate-reducing bacteria. At other times, chemical methods that measure the rates of appearance of metabolic derivatives or the utilization of contaminated product components might be indicated. In evaluating nonconventional tests, the use of these alternative standard procedures may be the only means available for establishing correlation. In such cases, this guide can serve as a reference for those considerations.
1.4 Since there are so many types of tests that could be considered nonconventional, it is impossible to recommend a specif...
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Designation:E 1326–06
Standard Guide for
Evaluating Nonconventional Microbiological Tests Used for
1
Enumerating Bacteria
This standard is issued under the fixed designation E 1326; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope types of tests should be considered to verify the utility and
identify the limitations of the nonconventional test.
1.1 Thepurposeofthisguideistoassistusersandproducers
of nonconventional tests in determining the applicability of the
2. Referenced Documents
testforprocessingdifferenttypesofsamplesandevaluatingthe
3
2.1 ASTM Standards:
accuracy of the results. Conventional procedures such as the
D 3870 Practice for Establishing Performance Characteris-
Heterotrophic (Standard) Plate Count, the Most Probable
4
tics for Colony Counting Methods in Microbiology
Number (MPN) method and the Spread Plate Count are widely
D 4012 Test Method for Adenosine Triphosphate (ATP)
cited and accepted for the enumeration of microorganisms.
Content of Microorganisms in Water
However, these methods have their limitations, such as perfor-
D 5245 Practice for Cleaning Laboratory Glassware, Plas-
mance time and degree of accuracy. It is these limitations that
ticware, and Equipment Used in MicrobiologicalAnalyses
have recently led to the marketing of a variety of non-
D 5465 Practice for Determining Microbial Colony Counts
conventional procedures, test kits and instruments.
from Waters Analyzed by Plating Methods
1.2 A conventional test is one that is widely accepted and
E 691 Practice for Conducting an Interlaboratory Study to
published as a standard microbiological method or related
Determine the Precision of a Test Method
procedure.Anew, nonconventional test method will attempt to
E 2250 Method for Determination of Endotoxin Concentra-
provide the same information through the measurement of a
tion in Water Miscible Metal Working Fluids
different parameter. This guide is designed to assist investiga-
torsinassessingtheaccuracyandprecisionofnonconventional
3. Summary of Guide
methods intended for the determination of microbial popula-
3.1 ASTM standard practices are referenced for use by
tion densities or activities.
producers and users to determine the potential utility of the
1.3 It is recognized that the Heterotrophic Plate Count does
nonconventional test. Users of tests who are unequipped for
notrecoverallmicroorganismspresentinaproductorasystem
2 performing standard microbiological tests are given recom-
(1, 2). When this problem occurs during the characterization
mendations for seeking out microbiological laboratories that
of a microbiological population, alternative standard enumera-
could perform collaborative studies to evaluate and verify the
tion procedures may be necessary, as in the case of sulfate-
information generated with the nonconventional tests.
reducing bacteria. At other times, chemical methods that
measure the rates of appearance of metabolic derivatives or the
4. Significance and Use
utilization of contaminated product components might be
4.1 This guide should be used by producers and potential
indicated. In evaluating nonconventional tests, the use of these
producers of nonconventional tests to determine the accuracy,
alternative standard procedures may be the only means avail-
selectivity, specificity, and reproducibility of the tests, as
able for establishing correlation. In such cases, this guide can
defined in Practices E 691 and D 3870. Results of such studies
serve as a reference for those considerations.
should identify the limitations and indicate the utility or
1.4 Since there are so many types of tests that could be
applicability of the nonconventional test, or both, for use on
considered nonconventional, it is impossible to recommend a
different types of samples.
specific test protocol with statistical analyses for evaluating the
4.2 Nonconventional test users and potential users should
tests. Instead, this guide should assist in determining what
employ this guide to evaluate results of the nonconventional
1
This guide is under the jurisdiction ofASTM Committee E35 on Pesticides and
Alternative ControlAgents and is the direct responsibility of Subcommittee E35.15
3
on Antimicrobial Agents. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2006. Published November 2006. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 1998 as E 1326 – 98. Standards volume information, refer to the standard’s Document Summary page o
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