Performance Summary
RAPID'Salmonella Method

Introduction
RAPID'Salmonella Agar is a chromogenic medium for thedetection of Salmonella spp. after food and environmental
samples are enriched in supplemented Buffered Peptone Water(BPW). The RAPID'Salmonella method allows the presumptive
identification of motile and nonmotile Salmonella spp., lactosepositive Salmonella spp., and Salmonella Typhi and Paratyphi
by detecting C8-esterase activity. Simultaneous screening ofb-glucosidase activity permits the differentiation of Salmonellacolonies from those of other Enterobacteriaceae. Afterincubation, Salmonella appear as readily identifiable, typicallymagenta, colonies, whereas non-Salmonella bacteria growas blue or colorless colonies. The RAPID'Salmonella method
has been rigorously tested and validated by internationallyrecognized validation agencies (Table 1).

Limit of Detection
Limit of detection (LOD50) is an estimation of the contaminationlevel required to achieve positive detection in 50% of cases.
This is measured by inoculating food matrices with Salmonella
strains and carrying out the validated enrichment anddetection protocols (Table 3).

Table 1. Validations for the RAPID'Salmonella method.
Validation

Certificate Number

AOAC

PTM 050701

NF Validation

BRD 07/11–12/05

NordVal32

Inclusivity/Exclusivity Testing
Inclusivity testing is performed to verify that the method
can detect Salmonella spp., while exclusivity studies test
non-Salmonella strains to ensure there is no cross-reactivity.
Exclusivity strains were enriched in nonselective broth for
24 hr at 41.5 ± 1°C and were tested at high levels. A targetof 10–100 colony forming units (CFU) of each Salmonella
inclusivity strain was cultured in supplemented BPW for
16–20 hr at both 37 ± 1°C and 41.5°C ± 1° and then diluted toa low level (~103) before testing. All colonies were confirmed
regardless of morphology. Results from the 2018 NF Validation
extension are shown in Table 2.
Table 2. Results of inclusivity/exclusivity testing.
Strains Tested

Positives Detected

Results

152 Salmonella strains tested

145/156

93% inclusivity

101 non-Salmonella strains tested 0/101** Confirmation included.

100% exclusivity

The average LOD50 of the RAPID'Salmonella method wasdetermined to be 0.7 (range: 0.6–0.9).
Table 3. LOD50 for the RAPID'Salmonella method.
Matrix/Strain Pair

LOD50, CFU/sample size (range)

Potato salad/S. Mbandaka

0.6 (0.3–1.2)

Ground beef/S. Infantis

0.7 (0.4–1.3)

Raw milk/S. Derby

0.5 (0.3–0.9)

Liquid egg product/S. Enteritidis

0.7 (0.4–1.2)

Haddock fillet/S. Saintpaul

0.5 (0.3–0.9)

Dog food/S. Agona

1.1 (0.6–2.0)

Process water/S. Typhimurium

1.0 (0.5–1.8)

Infant formula/S. Anatum

0.8 (0.5–1.4)

Infant formula with probiotics/S. Cerro

0.3 (0.1–0.5)

Method Comparison/Matrix Studies
Matrix testing is critical to demonstrating the performance ofa method compared to the reference method with real-world
food samples. The RAPID'Salmonella method has been verified
with external and internal testing on a wide variety of foods. No
significant difference was found between the reference method
and alternative method for all matrices tested (Table 4).

Performance Summary: RAPID'Salmonella Method

Table 4. Matrices tested with the RAPID'Salmonella method.
CategoryMatrices

Composite foods
RTE, RTRH, pastries and egg products

RTE: Mixed tuna with vegetables, cooked vegetable meal
RTRH: Frozen peas with bacon, moussaka, shepherd’s pie, spaghetti bolognese, beef bourguignon,
paella, trout with spices, sole fillet with lemon, cod with creamed spinach, herring with herbs, seasoned
beef, stuffing
Pastries and egg products: Chocolate éclair, pastry, chocolate custard puff pastry, caramel cream
puff, egg dessert, mayonnaise, chocolate meringue, confectioner’s egg custard powder, egg pasta
powder, fresh egg pasta

Meat products
Raw and RTC, RTE and RTRH, deliRaw and RTC: Ground beef, beef trim, beef shank, raw ham, lamb, pork chop, rump steak, pork belly,
chicken breast, chicken parts with skin, chicken parts without skin, chicken thigh, chicken drumstick,rooster with skin, mechanically separated meat, duck gizzard, hen, turkey thigh, turkey meat, beef andpork meatball
RTE and RTRH: Fresh sausage, dried sausage, beef carpaccio, pork, smoked duck, dried duck, chorizo
Deli: Cooked ham, smoked ham, cooked pork shoulder, duck liver pâtéDairy products
Raw milk and products, heat processed, frozen

Raw milk and products: Raw cow milk, unpasteurized cow milk, raw sheep milk, unpasteurized
sheep milk, raw cow milk cheese, unpasteurized cow milk cheese, unpasteurized goat cheese curd,
fresh cream
Heat processed: Milk powder, skim milk powder, whipped cream, pasteurized cheese, pasteurized
milk, skim milk
Frozen: Ice cream

Egg products
Unprocessed, processed, dry

Unprocessed: Egg yolk, whole shell eggs, raw liquid egg product
Processed: Pasteurized whole liquid egg
Dry: Whole egg powder, egg white powder, egg yolk powder, powder for custard, powder for pancakemix, powder for egg preparation

Fishery products
Raw and RTC, RTE and RTRH

Raw and RTC: Frozen breaded Alaskan hake, frozen grilled fish fillet, breaded hoki, frozen salmon
fillet, frozen sole fillet, frozen cod fillet, fresh cod fillet, frozen sea bream steak, frozen tuna steak, fresh
cutlassfish fillet, whiting fillet, coley fillet, ling fillet, raw salmon, mullet fillet
RTE and RTRH: Smoked salmon, smoked herring
Fresh: Cantaloupe, lettuce, cauliflower, mâche lettuce, red cabbage, tomato, green pepper, red pepper,zucchini, eggplant, leekProduce
Fresh, frozen, processed

Frozen: Green beans, artichoke hearts, mixed vegetables, spinach
Processed: Grated white cabbage, grated carrots, grated celery, mixed crudité, frozen vegetable cakes,
frozen creamed spinach, processed tomatoes, steamed green vegetables, frozen vegetable cake, readyto-reheat vegetables
Dried cereals, fruits, nuts, seeds, and vegetables

Peanut butter, roasted tagine spices, roasted tandoori spices, coriander, cinnamon, parsley

Infant formula and cereals

Infant formula with and without probiotics, infant cereal with and without probiotics, infant formulaingredients (lactoproteins, maltodextrin, whey powders, caseinate, starch, nonfat dry milk, whey
protein isolate)

Pet food and animal feed

Raw pet food, wet pet food, dry pet food, cat food, dog food, sausage for dog, animal feed, goat feed,chicken feed, pig feed, sheep feed, duck feed, dehydrated proteinEnvironmental samples

Process water, rinse water, wastewater, dust, food production environmental surfaces, surface wipe

RTC, ready to cook; RTE, ready to eat; RTRH, ready to reheat.

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