Insights from 30 years of Salmonella proficiency testing
Four years of Salmonella PT under varied conditions
The table below shows example data from the AXIO QCS Chocolate scheme over a four-year period. Inoculum levels ranged from 5–100 colony forming units per gram (CFU/g), with satisfactory performance varying from 64% to 100% per round. Most strains were typical, with only occasional atypical strains included. Tracking inoculum level, strain type and performance together enables comparisons across rounds and highlights how matrix properties influence recovery. Periodic negative samples confirm the ability to report true negatives and guard against default positive reporting.
Year Sample Round Contents
No. of results Level of target organism % correct Result Atypical
Same strain, different matrix
229
72
5
100
Pos
2015 712
Salmonella Oranienburg
2015 714
229
47
10
64
Pos
Salmonella Thompson
2015 710
233
76
5
97
Pos
Salmonella Oranienburg
2015 711
233
76
8
100
Pos
Salmonella Nottingham
2015 716
233
Escherichia coli ; Enterococcus faecalis ; Saccharomyces 76
<10
97
Neg
2016 714
233
38
20
96
Pos
Salmonella Panama
2016 710
237
37
30
100
Pos
Salmonella Stanley
Same strain, different levels
2016 711
237
37
80
100
Pos
Salmonella Thompson
2016 712
237
36
<10
97
Neg
Kocuria kristinae
2016 714
237
34
50
100
Pos
Salmonella Oranienburg; Enterobacter aerogenes
2016 710
241
84
20
99
Pos
Salmonella Livingstone
2016 711
241
83
50
98
Pos
Salmonella Oranienburg; Enterobacter aerogenes
2016 712
241
83
40
98
Pos
Salmonella Thompson
2016 714
243
57
40
95
Pos
Salmonella Thompson
2016 710
245
69
20
99
Pos
Salmonella Indiana
2016 711
245
69
100
99
Pos
Salmonella Indiana
2017 710
249
70
100
83
Pos
Yes
Salmonella Bredeney
2017 712
249
44
10
95
Pos
Salmonella Nottingham
2017 710
251
43
<10
93
Neg
Escherichia coli
2017 714
249
42
50
100
Pos
Salmonella Montevideo
Atypical strain
2017 710
253
43
5
100
Pos
Salmonella Bovismorbificans
253
78
5
99
Pos
2017 714
Salmonella Bracknell
2017 711
253
75
5
87
Pos
Salmonella Panama; Enterobacter cloacae
2017 712
253
75
15
100
Pos
Salmonella Manchester
2017 714
253
48
<10
98
Neg
Enterobacter aerogenes
2017 710
257
61
5
95
Pos
Salmonella Stanley; Citrobacter diversus
2017 711
257
65
10
100
Pos
Salmonella Manchester
2017 712
257
65
<10
98
Neg
Staphylococcus epidermidis
261
45
10
100
Pos
2018 710
Salmonella Manchester; Citrobacter freundii
261
45
5
96
Pos
2018 711
Salmonella Panama
Negative sample
261
45
50
100
Pos
2018 712
Salmonella Bovismorbificans
261
42
15
98
Pos
2018 714
Salmonella Stanley
2018 710
265
72
5
97
Pos
Salmonella Salford; Enterobacter aerogenes
265
72
10
100
Pos
2018 711
Salmonella Senftenberg
265
72
500
99
Neg
2018 712
Escherichia coli
265
68
20
97
Pos
2018 714
Salmonella Thompson
273
45
<10
91
Neg
2019 710
Citrobacter freundii
6
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