125 / 1195
A Most Probable Number (MPN) estimation of contamination levels was conducted, using the
1
appropriate reference method, on the day that the analysis of the test samples was initiated. The Least
2
Cost Formulations, Ltd. (LCF) MPN Calculator-Version 1.6 [5] was used to determine the MPN values and
3
95% confidence intervals.
4
5
Table 1. Inoculation Strain Selection
Sample Type
Strain Name
Strain ID
Strain Source
Meat and Seafood
Raw ground beef with soy
S. Typhimurium
DD1467
Unknown
Beef trim
S. Berta
DD1331
Sausage
Frankfurters
S. Thompson
DD1336
Chicken
Shrimp
S. Anatum
DD1332
Shrimp
Poultry and Eggs
Ground turkey
S. Heidelberg
DD 12913
Turkey
Chicken wings
Natural Flora
n/a
n/a
Dried eggs
S. Braendrup
DD1329
Sausage
Shell eggs
S. Enteritidis
ATCC13076
Unknown
Produce
Frozen peas
S. California
DD1668
Unknown
Orange juice
S. Worthington
DD4043
Unknown
Dairy Products
Nonfat dry milk
S. Haardt
DD1343
Environmental
Ice cream
S. Agona
DD1333
Chicken
Environmentals
Ceramic tile
S. Lexington
DD13068
Environmental
Plastic
S. Mbandaka
DD13240
Environmental
Miscellaneous
Peanut butter
S. St Paul
DD4102
Nuts
Cocoa
S. Sya
DD 2380
Unknown
White pepper
S. Newport
DD13079
Basil
Infant formula
S. Ealing
DD1469
Infant formula
6
Sample Enrichment
7
Many sample types were evaluated using multiple primary enrichment media to accommodate the
8
validation requirements of multiple countries, which require comparisons to different reference
9
methods (see Table 2). In addition, some sample types were evaluated with an alternative enrichment
10
medium to ensure optimal performance with the test method. All test portions enriched in an
11
alternative medium were subjected to secondary enrichment and confirmation procedures as outlined
12
in the appropriate reference method. Furthermore, in order to best meet the work flow preferences of a
13
wide variety of end users, many sample types were evaluated both before and after a re-growth step
14
(see Table 3).
15
Dupont BAX Salmonella Pre- Collaborative Study
For Expert Review Panel Use Only
Do Not Distribute
AOAC INTERNATIONAL