Food Protection Trends - May/June 2023 - 278

TABLE 3. Summary comparison of alternative methods
Methods normally used
Alternative methods
Are methods equivalent?
Method
Accreditation
APC
FDA BAM
Chapter 3
Method
Rapid indicator
organism assay
Accreditation
AOAC OMA
990.12
Yes, the method in column A is the
standard cultural reference method to
which the rapid assay was compared
and proven equivalent in an AOAC
accreditation study.
Rapid Salmonella
detection assay I
AOAC OMA
2016.01
Rapid Salmonella
detection assay II
AOAC OMA
2011.03
Yes, both rapid methods are AOAC
accredited to the same level (Official
Method of Analysis) and the AOAC
method accreditation studies include the
same reference method and nut matrices
validated at the same sample sizes.
TABLE 4. Summary comparison of tests in response to a supply-chain disruption
Method normally used
Potential alternative method
Are the methods equivalent?
Method
Accreditation
Method
Accreditation
Rapid Salmonella
detection assay I
AOAC OMA
2016.01
Rapid Salmonella
detection assay II
AFNOR NEO
35/02-05/13
No, the methods are not validated by
the same accreditation protocol and
different reference methods were used.
For products under FDA regulation, the
accreditation protocol must include an
FDA BAM reference method.
current cultural method. Hence both methods are equivalent,
and there is no barrier to switching. Their second interest
is in switching between two rapid Salmonella assays. On
examination of the method validations, they find that both
are validated against (and, hence, equivalent to) the same
reference method. Therefore, both rapid methods can be
considered equivalent to each other, and there is no barrier
to switching. In both cases the ability of the laboratory to
run the new methods effectively should be verified before
first use and then monitored through an ongoing proficiency
test program.
Example 2. The rapid test kits that a laboratory uses for the
detection of L. monocytogenes in chocolate are affected by a
supply chain disruption and will not be available for some
time. Another test kit lists chocolate in its validation studies.
However, the accreditation followed the ISO protocol against
an ISO reference method, and the product is regulated by the
278 Food Protection Trends May/June
FDA (Table 4). In this case, the methods might be equivalent,
but we need to examine the validation certifications to ensure
that the appropriate reference method (14) was used. If not,
the laboratory may still choose the alternative test kit but
should undertake some internal verification of its performance
against the FDA BAM reference method.
When methods deemed equivalent are examined in detail,
technical differences may be seen between them, including
the mechanism for detection (molecular or immunological),
LOD, and the TAT (Table 5). However, as long as the methods
are all sensitive to the level claimed in their validation
study, they are all equivalent in their ability to detect a pathogen.
In practice, method developers tend to trade increased
detection sensitivity for shorter enrichment times and, hence,
shorter TATs. Less-sensitive detection technologies will have
longer enrichment times to increase the target analyte to
levels above the limit of detection. Even if the protocol differs
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