227 / 453
15
A background screen of the matrix indicated an absence of indigenous
E. coli
O157:H7. Ten (10)
1
replicate test portions (randomly sampled from 50% of the total packages used in the analysis)
2
were screened for the presence of
E. coli
O157:H7. All test portions produced negative results
3
for the target analyte.
4
5
Table 2016.1A and 2016.1D summarize the inter-laboratory results for each assay (screening and
6
confirmatory) for both manual and automated preparation steps. As per criteria outlined in
7
Appendix J of the AOAC Validation Guidelines, fractional positive results were obtained.
8
Detailed results for each laboratory are presented in Tables 2016.2A and 2016.2D. The level of
9
E. coli
O157:H7 was determined by MPN on the day of initiation of analysis by the coordinating
10
laboratory. The MPN levels obtained, with a 95% confidence interval, were 0.62 CFU/test
11
portion (0.48, 0.77) for the low inoculum level and 5.13 CFU/test portion (3.45, 7.62) for the
12
high inoculum level.MPN results are presented in the second column of Tables 2016.2A and
13
2016.2D. The individual laboratory and sample results are presented in Tables 1-2 of the
14
Supplementary Materials. The APC results for each collaborating are presented in Table 3 of the
15
Supplementary Materials.
16
17
Raw Ground Beef –
mericon
E. coli O157Screen Plus with Manual Preparation
18
For the low inoculum level, 69 out of 144 test portions (POD
CP
of 0.48) were reported as
19
presumptive positive by the
mericon
E. coliO157Screen Plus with 65 out of 144 test portions
20
(POD
CC
& POD
R
of 0.45 due to paired sample enrichment) confirming positive. For samples that
21
produced presumptive positive results on the
mericon
E. coliO157Screen Plus, 65 out of 144
22
samples confirmed positive (POD
C
of 0.45; value include only presumptive positive results that
23
confirmed positive). A dLPOD
C
value of 0.00 with 95% confidence interval of (-0.12, 0.12) was
24
obtained between the candidate and reference method, indicating no statistically significant
25
difference between the two methods. A dLPOD
CP
value of 0.03 with 95% confidence intervals of
26
(-0.09, 0.15) was obtained between presumptive and confirmed results indicating no statistically
27
significant difference between the presumptive and confirmed results.
28
29
For the high inoculum level, 144 out of 144 test portions (POD
CP
of 1.00) were reported as
30
presumptive positive by the
mericon
E. coliO157Screen Plus with 144 out of 144 test portions
31
(POD
CC
& POD
R
of 1.00) confirming positive. For samples that produced presumptive positive
32
results on the
mericon
E. coliO157Screen Plus, 144 out of 144 samples confirmed positive
33
(POD
C
of 1.00). A dLPOD
C
value of 0.00 with 95% confidence interval of (-0.03, 0.03) was
34
obtained between the candidate and reference method, indicating no statistical significant
35
difference between the two methods. A dLPOD
CP
value of 0.00 with 95% confidence intervals of
36
(-0.03, 0.03) was obtained between presumptive and confirmed results indicating no statistically
37
significant difference between the presumptive and confirmed results.
38
39
For the un-inoculated controls, 3 out of 144 samples (POD
CP
of 0.02) produced a presumptive
40
positive result by the
mericon
E. coli O157Screen Plus with 0 out of 144 test portions (POD
CC
&
41
POD
R
of 0.00) confirming positive. For samples that produced presumptive positive results on
42
the
mericon
E. coliO157Screen Plus, 0 out of 144 samples confirmed positive (POD
C
of 0.00).
43
OMAMAN-36 A : Collaborative Study Manuscript
For ERP Use Only
January 2017
AOAC R search Institute
Expert Review Panel Use Only