AOAC-RI ERP Micro June 2016

OMAMAN-29/OMAMAN-30 Combined Collaborative Study Protocol OMA ERP - June 2016 ERP Use Only

3M MDA 2 Listeria species and L. monocytogenes Collaborative Study OMA-2016-MONTH-XXX

2.14.3 Streak a MOX plate. Streak a loopful or a drop approximating 0.1 ml of the enriched sample over the surface of the plate. Incubate the MOX at 35 2.14.4 Examine the MOX plates for colonies with morphology typical of Listeria spp . At 26 ± 2 h, suspect colonies are typically small (ca. 1 mm) and are surrounded by a zone of darkening due to esculin hydrolysis. 2.14.5 If suspect colonies are present on MOX, transfer suspect colonies to HL ± 2°C for 26 ±2 h. 2.14.7 After 26 ± 2 h of incubation, examine the FB for the potential presence of Listeria spp., by visual examination of the broth for darkening due to 2.14.8 If any degree of FB darkening is evident, aseptically dispense a drop approximating 0.1 ± 0.02 ml of FB onto a MOX plate. Swab or streak 25- 40% of the surface of the MOX plate with the FB inoculum. Use a loop to streak for isolation from the initial swab/streak quadrant onto the remainder of the plate. Incubate the MOX plate at 35 ± 2°C for 26 ± 2 h. 2.14.9 If no FB darkening is evident, re-incubate the FB at 35 ± 2°C until a total 2.14.10Re-examine the FB for evidence of darkening after 48 ± 2 h of total incubation. If any degree of darkening is evident, swab, streak and 2.14.11If no darkening of FB is evident and no suspect MOX and/or HL colonies have been demonstrated, the sample is considered negative for Listeria 2.14.12If suspect colonies are present on MOX from any source, streak for isolation on one or more HL agar plates. Incubate the streaked HL at 35 ± colonies surrounded by a small zone of β-hemolysis. AOAC Research Institute Exp rt Review Panel Use Only 2.14.14If at least one suspect colony is clearly isolated, proceed to confirmatory testing. Hold all HL plates containing suspect colonies (room temperature or refrigeration) until confirmatory testing is complete. 2.14.15If suspect colonies or β-hemolytic growth are present on HL but not clearly isolated, re-streak representative suspect colonies/growth onto one or more fresh HL plates and incubate at 35 ± 2°C for 22 ± 4 h. 2.14.16Confirm ALL test portions according to the USDA FSIS MLG 8.09 biochemical/serological procedures. Biochemical tests will be performed using API or VITEK 2 GP. Please follow manufacturer’s instructions esculin hydrolysis. incubation time of 48 ± 2 h has been achieved. incubate a MOX plate. spp. 2°C for 22 ± 4 h. 2.14.13After incubation, examine the HL plate(s) against backlight for translucent agar. 2.14.6 If no suspect colonies are evident, re-incubate the MOX plate for an additional 26 ± 2 hour.

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when using any of these rapid methods.

USDA FSIS Reference Method

1.17 Add 25g test portion to 225 mL UVM broth. Stomach (Seward 400 or equivalent)

for 2± 0.2 minutes and incubate for 20-26h at 30 ± 2 ° C.

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