1075 / 1195
REVISED 121213
for inclusivity of 99.1%. One strain of
S
. Weslaco, previously identified as a non-inclusive strain lacking
1
the genetic target for the ANSR assay, produced negative results from all 7 media. In testing of exclusive
2
strains, 248 of 251 assays produced negative results, for accuracy of 98.8%. The pre-collaborative study
3
report is included as Appendix I.
4
Here we report results of an interlaboratory collaborative study conducted in 18 laboratories for further
5
evaluation of the assay as a colony confirmation tool.
6
7
Collaborative Study
8
Study Design
9
This collaborative study was conducted in accordance with the
AOAC INTERNATIONAL Methods
10
Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces,
11
Appendix J
[8]. Eighteen laboratories participated in the collaborative study, representing industry,
12
academic, government, and private testing laboratories. All collaborators were either established users
13
of the ANSR test system or were expressly trained for the collaborative study prior to its
14
commencement. A detailed set of instructions and data recording forms were sent to each collaborator
15
in advance of the study. Collaborators were provided with all necessary agar plating media, test kits,
16
ANSR system instrumentation, and a blind-coded set of 12 bacterial cultures for analysis.
17
Preparation of Isolates
18
All isolates were from the Neogen Corp. culture collection and consisted of 6 diverse strains of
19
Salmonella enterica
and
Salmonella bongori
, and 6 strains of Enterobacteriaceae belonging to other
20
genera (Table 1). All strains were obtained directly from the American Type Culture Collection (ATCC,
21
Manassas, VA). Identity of isolates was confirmed by API 20E testing.
Salmonella
isolates were also
22
verified by O group serology. Isolates were cultured on TSA slants for 18-24 h at 36 ± 1
o
C. Slant cultures
23
were labeled with a two-digit alphabetical code.
24
Distribution of Isolates
25
Cultures were shipped to collaborators via overnight delivery, at ambient temperature, using Category B
26
Dangerous Goods packaging as set forth by International Air Transport Association regulations.
27
Collaborators were instructed to store the cultures at 2-8
o
C until initiation of the analytical work (4-5
28
3