ASTM E1326-98

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:E 1326–98
Standard Guide for
Evaluating Nonconventional Microbiological Tests Used for
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
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
tics for Colony Counting Methods in Bacteriology
Number (MPN) method and the Spread Plate are widely cited
D 5245 Practice for Cleaning Laboratory Glassware, Plas-
and accepted for the enumeration of microorganisms. How-
ticware and Equipment used in Microbiological Analysis
ever,thesemethodshavetheirlimitations,suchasperformance
D 5465 Practice for Determining Microbial Counts From
time and degree of accuracy. It is these limitations that have
Waters Analyzed by Plating Methods
recently led to the marketing of a variety of non-conventional
E 691 Practice for Conducting an Interlaboratory Study to
procedures, test kits and instruments.
Determine the Precision of a Test Method
1.2 A conventional test is one that is widely accepted and
published as a standard microbiological method or related
3. Summary of Guide
procedure.Anew, nonconventional test method will attempt to
3.1 ASTM standard practices are referenced for use by
provide the same information through the measurement of a
producers and users to determine the potential utility of the
different parameter. This guide is designed for comparing
nonconventional test. Users of tests who are unequipped for
levels of bacteria recovered from samples by the Heterotrophic
performing standard microbiological tests are given recom-
Plate Count Procedure to the equivalent units determined with
mendations for seeking out microbiological laboratories that
a nonconventional test.
could perform collaborative studies to evaluate and verify the
1.3 It is recognized that the Heterotrophic Plate Count does
information generated with the nonconventional tests.
not recover all microorganisms present in a product or a
system (1). When this problem occurs during the character-
4. Significance and Use
ization of a microbiological population, alternate standard
4.1 This guide should be used by producers and potential
enumeration procedures may be necessary, as in the case of
producers of nonconventional tests to determine the accuracy,
sulfate-reducing bacteria. At other times, chemical methods
selectivity, specificity, and reproducibility of the tests, as
that measure the rates of appearance of metabolic derivatives
defined in Practices E 691 and D 3870. Results of such studies
or the utilization of contaminated product components might
should identify the limitations and indicate the utility or
be indicated. In evaluating nonconventional tests, the use of
applicability of the nonconventional test, or both, for use on
these alternate standard procedures may be the only means
different types of samples.
available for establishing correlation. In such cases, this guide
4.2 Nonconventional test users and potential users should
can serve as a reference for those considerations.
employ this guide to evaluate results of the nonconventional
1.4 Since there are so many types of tests that could be
testascomparedtotheirpresentmethods.PracticesD 5245–92
considered nonconventional, it is impossible to recommend a
and D 5465–93 should be reviewed in regards to the conven-
specific test protocol with statistical analyses for evaluating the
tional microbiological methods employed. If conventional
tests. Instead, this guide should assist in determining what
methods have not been used for monitoring the systems, then
guidelines are included for obtaining microbiological exper-
tise.
This guide is under the jurisdiction ofASTM Committee E35 on Pesticides and
is the direct responsibility of Subcommittee E35.15 on Antimicrobial Agents.
Current edition approved Oct. 10, 1998. Published December 1998. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
published as E 1326 – 90. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The boldface numbers in parentheses refer to the list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this guide. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1326–98
4.3 Utilization of a nonconventional test may reduce the permitthedeterminationofwhetherornotthenonconventional
time required to determine the microbiological status of the method achieves the objectives defined in the scope of the
system and enable an improvement in the overall operating
procedure.
efficiency. In many cases, the findings of a significantly high
5.2 A knowledge of standard microbiological technique is
level of bacteria indicates the need for an addition of an
required for this procedure. If that expertise is not currently
antimicrobialagent.Byaccuratelydeterminingthisinashorter
available in-house, then consult an outside testing laboratory.
time period than by conventional methods, treatment with
Many industrial microbiology laboratories are certified for the
antimicrobial agents may circumvent more serious problems
analysis of drinking water by the EPAor the state government
than if the treatment were postponed until conventional results
(a listing of these laboratories can be obtained from the
wereavailable.Iftheantimicrobialtreatmentprogramrelieson
regional EPA office or the state government). There are also
an inaccurate nonconventional test, then unnecessary loss of
other microbiology laboratories that specialize in processing
product and problems associated with inappropriate selection
samples from different industries; these are often listed as
or improper dosing with antimicrobial agents would exist.
“Laboratories—Testing” in the telephone book. It is important
4.4 Since many methods based on entirely different chemi-
that this document be referenced when undertaking an evalu-
cal and microbiological principles are considered, it is not
ation with an outside laboratory.
possible to establish a unique design and recommend a specific
method of statistical analyses for the comparisons to be made.
5.3 For each method, first make an enumeration of all major
It is only possible to present guides that should be followed
sources of variability. For example, if a nonconventional test
while performing the experiments. It is also recommended that
method is involved and if more than a single analysis can be
a statistician be involved in the study.
conductedwithasingletest,considerthevariabilitywithinand
between tests. For plates, it is important to consider the
5. Procedures
variability between plates obtained from aliquots of the same
5.1 In order to determine the utility of the nonconventional
sample. It is also important to prepare samples covering t
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