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SUBMITTED 050113, REVISED 102513
Results are presented in Tables 1 and 2. All 113
Salmonella
spp. strains tested produced positive results
1
(“
Salmonella
spp.”) from all 7 agar media with a single exception. The known non-inclusive strain of
S
.
2
Weslaco produced negative results from all agar media tested. A second strain of
S
. Weslaco produced
3
positive results from all agar media. Overall inclusivity of the ANSR confirmation method was 99.1%.
4
5
Of the 259 plates streaked with exclusive strains, there were 14 cases of no growth and no ANSR test
6
performed (see Table 2). Of 245 ANSR tests performed on exclusive strains, 242 produced negative
7
results (“not
Salmonella
spp.”) for overall accuracy on exclusive strains of 98.8%. A colony of
8
Enterobacter intermedia
from DMLIA agar, and a colony of
Escherichia hermanii
from XLT4 agar
9
produced weakly positive, atypical ANSR fluorescence curves. A colony of
Edwardsiella tarda
from XLD
10
agar produced a strong positive ANSR curve. Re-tests of these strain/colony combinations all produced
11
negative results. The cause of the aberrant results is not known, although cross-contamination and/or
12
sample handling or pipetting errors are suspected.
13
14
Considering the total of 784 results on inclusive stains (non-inclusive
S
. Weslaco strain excluded) and
15
245 results on exclusivity strains, overall accuracy of the ANSR confirmation method in initial testing was
16
99.7%.
17
18
Example assay curves for positive and negative results are shown in Fig. 1. Almost without exception,
19
assay curves generated for
Salmonella
spp. were very robust and of the type shown in the example.
20
21
Recommendations
22
Based on results of this pre-collaborative study, it is recommended that the ANSR
Salmonella
test
23
application for identification of
Salmonella
spp. from colony picks proceed to inter-laboratory
24
collaborative study.
25
26
27
28
29
References
30
32