AOAC-RI ERP Book MICRO Sept 2016.pdf

OMAMAN-08/Collaborative Study Protocol March 2014 Expert Review Panel Use Only

3M Petrifilm SALX Collaborative Study

July 2013

OMA-2013-July-XXX

Reference Pre-enrichment

3M Petrifilm SALX 1° Enrichment

3M Petrifilm SALX 2° Enrichment

Food Type

Reference

Raw ground beef (80/20)

3M Salmonella enrichment + supplement 3M Salmonella enrichment + supplement

Rappaport-Vassiliadis R10 (R-V R10) Broth

USDA-MLG 2

BPW

25g-SALX 25g-MLG

Dry dog food 375g-SALX 25g-BAM

FDA-BAM 3

Lactose broth

None

1 2 3 4 5 6 7 8 9

Ground beef - 3M Petrifilm SALX

1.0

1.1 Aseptically add the 25g test portion to 225 mL pre-warmed (41.5°C) 3M Salmonella

Enrichment Base with supplement.

1.2 1.3

Mix in a Stomacher® bag with filter for 2 min.

Incubate 18-24 hr at 41.5 ± 1°C.

1.4 After primary enrichment incubation, transfer 0.1 mL of the primary enrichment into 10 mL Rappaport-Vassiliadis R10 (R-V R10) Broth. Incubate at 41.5 ± 1.0°C for 8-24 hours. 1.5 Prior to analysis, hydrate the 3M Petrifilm SALX Plates using 2.0 mL of sterile distilled water. After hydration, the liquid was spread across of the surface of the plate using a plastic spreader to evenly distribute the diluent. The plates were left undisturbed and

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

protected from light for a minimum of 1 hour prior to use.

1.6 Streak each enriched test portion onto 3M Petrifilm SALX plate and incubate at 41.5° ±

1°C for 24 ± 2 hours.

Alternative 3M SALX Confirmation Method

1.7

1.7.1 Using a fine tip marker, circle presumptive positive colonies (red to brown colonies with discrete yellow zones and/or gas bubbles) on the plate top film. 1.7.2 Lift the top film and place a 3M Petrifilm Salmonella Express Confirmation Disk onto the gel. Close the film using a gloved hand (while practicing good laboratory technique) and remove air bubbles by gently applying a sweeping motion with even pressure onto the top of the film with the analyst’s fingers. 1.7.3 Incubate the plates with confirmation disks at 41.5° ± 1°C for 4 to 5 hours. 1.7.4 Observe circled colonies for color change - red/brown to green blue, blue, dark blue or black confirm the colony as Salmonella species. No color change, colony

AOAC Research Institute Expert Review Panel Use Only

is negative.

1.7.5 Transfer typical colonies from SALX plate to TSI/LIA slants. Incubate 35 ± 1 ° C for

24 ± 2h.

1.7.6 Confirm a minimum of one typical colony per test portion with

biochemical/serological procedures prescribed by the USDA/FSIS method. Either the API20E (Official Method 978.24) or the VITEK GN (Official Method 2011.17) will be used as an alternative to the conventional biochemical tests. The

somatic (O) and flagellar (H) tests will also be performed.

2 http://www.fsis.usda.gov/PDF/MLG_4_05.pdf 3 http://www.fda.gov/Food/ScienceResearch/LaboratoryMethods/BacteriologicalAnalyticalManualBAM/ucm070149.htm

DRAFT DOCUMENT

16