230 / 453
18
0.10) was obtained between presumptive and confirmed results indicating no statistically
1
significant difference between the presumptive and confirmed results.
2
3
For the high inoculum level, 141 out of 144 test portions (POD
CP
of 0.98) were reported as
4
presumptive positive by the
mericon
E. coliSTEC O-Type with 144 out of 144 test portions
5
(POD
CC
& POD
R
of 1.00) confirming positive. For samples that produced presumptive positive
6
results on the
mericon
E. coliSTEC O-Type, 141 out of 144 samples confirmed positive (POD
C
7
of 0.98). A dLPOD
C
value of -0.02 with 95% confidence interval of (-0.06, 0.01) was obtained
8
between the candidate and reference method, indicating no statistically significant difference
9
between the two methods. A dLPOD
CP
value of -0.02 with 95% confidence intervals of (-0.06,
10
0.01) was obtained between presumptive and confirmed results indicating no statistically
11
significant difference between the presumptive and confirmed results.
12
13
For the un-inoculated controls, 1 out of 144 samples (POD
CP
of 0.01) produced a presumptive
14
positive result by the
mericon
E. coliSTEC O-Type with 0 out of 144 test portions (POD
CC
&
15
POD
R
of 0.00) confirming positive. For samples that produced presumptive positive results on
16
the
mericon
E. coliSTEC O-Type, 0 out of 144 samples confirmed positive (POD
C
of 0.00;
17
value). A dLPOD
C
value of 0.00 with 95% confidence interval of (-0.03, 0.03) was obtained
18
between the candidate and reference method, indicating no statistically significant difference
19
between the two methods. A dLPOD
CP
value of 0.01 with 95% confidence intervals of (-0.02,
20
0.04) was obtained between presumptive and confirmed results indicating no statistically
21
significant difference between the presumptive and confirmed results.
22
23
Detailed results of the POD statistical analysis are presented in Table 2016.2Dand Figures 4A-
24
4B.
25
26
Discussion
27
28
No negative feedback was provided with regard to the manual preparation of the assay or the
29
performance of
mericon
assays on the Rotor Gene Q thermocycler. Two technicians (Laboratory
30
6 & 11) experienced issues with the automated extraction procedure. Further investigation into
31
the issues indicated the problems were a result with unfamiliarity of the instrument which led to
32
the software, and or mechanical, errors. Based on the feedback from the collaborators, it is
33
recommended that analysts using the automated extraction platform be well versed in PCR
34
analysis and receive a thorough training prior to use of the automated platform.
35
36
Overall, the data generated during this evaluation demonstrates the reproducibility of this new
37
method. No statistically significant differences were observed between the presumptive methods
38
(
mericon
E. coliO157Screen Plus and
mericon
E. coliSTEC O-Type) and the confirmed results.
39
A few false positive results were observed for both the manual and automated procedures. Some
40
of the false positive results observed for the
mericon
E. coliO157Screen Plus assay were due to
41
the detection of the virulence genes for STEC and not for the detection of E. coliO157.
42
43
OMAMAN-36 A : Collaborative Study Manuscript
For ERP Use Only
January 2017
AOAC Research Institute
Expert Review Panel Use Only