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In this study, a single primer probe assay kit lot wasstored at 4 + 1
o
C for 4 and 15 months.
A second set of kits from the same lot was stored at 37 + 1
o
C for 3 and 4.5 months. The
twosets of primer probes stored at 37 + 1
o
C extend the real time aging to approximately 18
and 24 months [9]. The same lot of Master Mix was used for all time points from 0 to 15
months. The 15 month time point kits were assayed once with the original Master Mix and
in parallel with a fresh Master Mix. The study used purified reference DNA diluted from
10,000 to 10 copies per reaction.
For the
mericon
E. Coli O157 Screen Plus stability studies, the reference DNA was a
synthetic E. coli Big 6 gBlock DNA (IDT) containing eae, stx1/stx2 and O157 components.
Aliquots of the gBlock DNA were stored at -20°C, thawed and serially diluted prior to each
test point.
For the
mericon
E. coli STEC O-type stability studies, the reference DNAwas prepared
from E. coli strains O157:H7 (RM-HYG374) and O26 (RM-HYG375) (ifp culture
collection)..The DNA concentration was adjusted to 10,000 copies/µl and stored in aliquots
at -20°C. For testing, an aliquot was thawed and serially diluted prior to each test point.
Results
Inclusivity and Exclusivity Evaluation
Of the 50 inclusivity organisms assessed for both the
mericon
E.coliO157Screen
Plus and
mericon
E.coliSTEC O-Type Pathogen Detection Assays, all were correctly
identified.
.
Similarly, all 30 exclusivity organisms examined using the twoE.coliSTEC
O-Type Pathogen Detection Assays were correctly excluded.
Detailed results for the inclusivity and exclusivity validations are presented in Tables
1 - 4 of the Appendix.
Matrix Study
Results obtained from samples analyzed by the
mericon
methods were statistically
comparable to those analyzed by the FDA/BAM or USDA/FSIS-MLG reference
methods. The POD analysis between
mericon
methods and the reference methods
for all matrixes indicated that there was no significant difference at the 5% level
between the number of positive results by the two methods.
As per criteria outlined in Appendix J of the Official Methods of Analysis Manual,
fractional positive results were obtained [11]. A detailed summary of results for each
matrix is displayed below in Table 5 and Table 6.
The pre-evaluation pathogen screening and aerobic plate count (APC) results are
presented in Table 5 of the Appendix. A summary of the MPN results is presented in
Tables 6A-6C of the Appendix. A detailed summary of results for each matrix is
presented in Tables 7-12 of the Appendix.
OMAMAN-36 E/ AOAC PTM Report
ERP Use Only
January 2017
AOAC Research Institute
Expert Review Panel Use Only