AOAC ERP MICRO AUGUST 2018

Table 998.09C. Statistical analyses of results for 3M TECRA assay with selective enrichment in tetrathionate broth only compared to BAM, 7th Ed.

Incidence of false negatives among total positive suspensions, % d VIA Culture

Incidence of false positives among total negative suspensions, % f VIA Culture

Sensitivity rate, % e

Specificity rate, % g

MPN a (CFU/g)

Method agreement, % b

c 2 c 0.0

Food (No. labs)

VIA Culture

VIA Culture

— h

Milk chocolate (14) <0.003

100 100

— — — 0

8.6 2.3 2.1 0.0 0.0 0.0 0.0 0.0 0.0 4.0 0.9 1.2 1.3 0.0 0.0

100 100 100 99 100 100 100 100 100 100 100 100 99 100

91 98 98 100 100 100 100 100 100 96 99 99 99 100 100

0.009

— 0.0

0.0 0.0

100 98

100 100

0.0 0.0

0.093 98.6

0.5 0.0

2.2

— — — — 3.0 (4.6v) i

Dried whole egg (13) <0.003 98.4

97 (95v)

0.009 0.430

100 100 100

— 0.0 — 0.0

0.0 0.0

100 100

100 100

1.1 0.0

Nonfat dry milk (18) <0.003

— — — — — 0.0

0.24

98.8

0.0 0.0

1.3 1.3

0.0 0.0

99 99

100 100

0.0 0.0

2.4

100 100

Black pepper (15) <0.003

— — — — — 0.0

0.014 98.7 0.088 97.3

0.0 0.5

2.7 3.0

0.0 0.0 0.0 0.0 0.0

97

100 100 100 100 100

0.0 0.0 0.0 1.2 0.0

97

Soy flour (15)

<0.003

100 100 100 100

— 0.0 — 0.0 — 0.0

100 100 100

0.24

2.4

— — — — — 3.3 (5.0r) i 55

Raw turkey (12)

<0.003

96.7 (95.0r) 45

0.043 91.6

0.0

5.6

3.6 5.1

94.6 96.4

3.1 0.0

7.8 4.7

96.9 92.2 100 95.3

0.46

91.6

— 0.0

100

100

a–i See Table 998.09D for footnotes.

Include single positive and negative control antigens with each group of tests. All controls must function properly for test to be valid. Use data record sheet to identify location of each test product. Use separate pipets for each test and kit reagent to avoid cross-contamination. If plastic troughs are used to dispense conjugate and substrate, ensure that they are always kept separate. Components in kits are intended for use as integral unit. Do not mix components of different batch numbers. E. Preparation of Suspensions for 3M TECRA VIA ( a ) Pre-enrichment .—Pre-enrich product in noninhibitory broth to initiate growth of Salmonella spp. Methods used may vary with product and should be performed as indicated in 967.26 A ( see 17.9.02), or in Bacteriological Analytical Manual , 8th Ed., AOAC INTERNATIONAL, Gaithersburg, MD 20877, USA, Chapter 5, section C. Incubate pre-enrichment broths at 36 ° ± 1 ° C. ( b ) Selective enrichment .—( 1 ) Option 1 (2 selective broths) .—Transfer 0.1 mL incubated pre-enrichment mixtures to Rappaport-Vassiliadis R10 broth (9.9 mL) and 1 mL to tetrathionate broth (9 mL). ( 2 ) Option 2 (Rappaport-Vassiliadis R10 broth only) .—Transfer 0.1 mL incubated pre-enrichment mixture to Rappaport-Vassiliadis R10 broth (9.9 mL). ( 3 ) Option 3 (tetrathionate broth) .—Transfer 1 mL incubated pre-enrichment mixture to tetrathionate broth (9 mL). For all foods other than raw foods or foods having a high microbial load, incubate 6 ! 8 h at 42 ° ± 1 ° C. Selective enrichments

of raw foods or foods having a high microbial load must be incubated 16 ! 20 h at 42 ° ± 1 ° C. ( c ) Post-enrichment .—Remove selective broths from incubation and mix by hand or by Vortex mixer. For options 1 and 3, remove 1 mL from tetrathionate tube and transfer to tube of sterile M broth (10 mL) which has beenwarmed to 36 ° ± 1 ° C. For options 1 and 2, remove 1mLfrom Rappaport-Vassiliadis R10 tube and transfer to separate tube of prewarmed M broth. Retain remaining Rappaport-Vassiliadis R10 broth and tetrathionate broth in refrigerator for later confirmation if necessary. For all foods other than raw or highly contaminated products, incubateMbroth tubes 16 ! 20h at 36 ° ± 1 ° C. For raw foods or foods having a high microbial load, incubate M broth tubes 6 h at 36 ° ± 1 ° C. ( d ) Preparation for EIA analysis .—Remove M broth tubes from incubation andmix tubes by hand or with Vortexmixer. For option 1, combine equal aliquots of 0.5 - 1 mL from each of the 2 M broth tubes (one from the tetrathionate enrichment and one from the Rappaport-Vassiliadis R10 enrichment), and heat in boiling H 2 O bath or in flowing steam 15 min. Refrigerate (2 ° –8 ° C) remaining Mbroth and tetrathionate and Rappaport-Vassiliadis R10 tubes from E ( c ) for culture confirmation of any EIA positive products. Cool heated M broths to 25 ° –37 ° C prior to analysis by EIA, G . F. Preparation of Suspensions for 3M TECRA ULTIMA ( a ) Pre-enrichment.— Pre-enrich product in noninhibitory broth to initiate growth of Salmonella spp. Methods used may vary with product and should be performed as indicated in 967.26 A ( see 17.9.02), or in Bacteriological Analytical Manual , 8th Ed., AOAC

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