878 / 1195
USDA/FSIS Reference Method
–
130
1.
Each 25g test portion was added into 225 mL modified University of
131
Vermont (UVM) broth and was stomached for 2 minutes and incubated for
132
24 h at 30
±
2
°
C.
133
2.
Secondary enrichment and isolation were conducted according to
134
Appendix 3.1. Additionally, all enriched test portions were streaked onto
135
ALOA agar and follow package insert instructions. One typical colony
136
either from the ALOA plate of the horse-blood plate were taken for
137
confirmation on VITEK 2.
138
3.
All the test portions were tested according to the USDA FSIS
139
biochemical/serological procedures (Appendix 3.1). A typical colony from
140
the horse-blood plate was used for confirmation on VITEK 2.
141
142
AOAC Reference Method
143
1.
Each 25g test portion was added into 225 mL selective enrichment
144
medium, shaken for 2 min according to AOAC 993.12 and incubated for 48
145
h at 30
°
C.
146
2.
Each enriched test portion was streaked onto Oxford medium and
147
incubated 48 h at 37
°
C.
148
3.
Additionally, all enriched samples were streaked onto ALOA agar and
149
follow package insert instructions. One typical colony was streaked on
150
horse-blood agar for hemolysis reaction and the typical colony was
151
confirmed on VITEK 2.
152
153
Statistical Analysis
154
The Probability of Detection model and chi-squared analysis were used to analyze
155
data from the Matrix Study.
156
157
Probability of Detecion
158
Probability of detection is the proportion of positive analytical outcomes for a
159
qualitative method for a given matrix at a given analyte level or concentration.
160
POD is concentration dependent. Several
POD measures were calculated; POD
R
161
(reference method POD), POD
C
(confirmed candidate method POD), POD
CP
162
(candidate method presumptive result POD) and POD
CC
(candidate method
163
confirmation result POD).
164
165
The POD estimate was calculated as the number of positive outcomes divided by
166
the total number of trials. Estimations were made for the POD with a 95%
167
confidence interval for the candidate method, the reference method and, if
168
included, the presumptive and confirmed results.
169
PTM Certification Modification Report