RapidChek SELECT Salmonellafor the Detection of Salmonella spp. in Raw Ground Beef, Raw Ground Chicken, Chicken Carcass Rinsates, Liquid Eggs, and Sliced Cooked Turkey

Abstract

The RapidChek SELECT Salmonella method was validated for the detection of Salmonella spp. in raw ground beef, raw ground chicken, chicken carcass rinsates, liquid eggs, and sliced cooked turkey. The method utilizes proprietary primary and secondary enrichment media. Following enrichment, an immunochromatographic test strip is inserted into the tube containing the secondary enrichment broth, developed for 10 min and interpreted. Naturally-contaminated (ground chicken) and Salmonella-inoculated food samples (1 to 10 CFUSalmonella/ 25 g sample) were tested by the method as well as a cultural reference method (FSIS/USDA). A total of 200 samples were tested by both methods in the study. Ninety (90) samples were positive by the RapidChek SELECT Salmonella method and 74 were found positive by the reference method. The accuracy of the test method was 122%. The RapidChek SELECT Salmonellamethod was tested with 113 strains of Salmonella representing 18 serogroups in addition to 50 strains of non-Salmonellabacteria that are commonly found in food. The RapidChek SELECT Salmonella method detected 111 of the Salmonella strains and none of the non-Salmonella bacteria were detected, indicating a sensitivity of 98% and specificity of 100%. The method was shown to be highly robust and stable under control (4 to 25C) and accelerated stability conditions (37 to 45C).

Method Authors

Mark T. Muldoon, Jingkun Li, Meredith Sutzko, Ann Christine Olsson-Allen, and GeorgeTeaney

Submitting Company

Strategic Diagnostics Inc.

128 Sandy Drive

Newark, DE19713

Independent Laboratory

SillikerResearchCenter

160 Armory Drive

South Holland, IL60473

Reviewers

Edward Richter, Ph.D.

Richter International, Inc.

505 King Avenue, Columbus, OH43201

Purnendu C. Vasavada, Ph.D.

Food Science Department

University of Wisconsin

River Falls, WI54022

  1. Scope of method

1.1 Target Organism.—Salmonella spp.

1.2 Matrices.—Raw ground beef, raw ground chicken, chicken carcass rinsates, sliced cooked turkey, liquid eggs

1.3 Summary of validated performance claims — The immunochromatographic test strip-based RapidChek SELECT Salmonella method was evaluated and shown to give 98% sensitivity (inclusivity) and 100% specificity (exclusivity) in this study. In method comparison studies, the accuracy of the test method relative to the FSIS/USDA reference method was 122% where 90 samples were found to be positive with the test method while 74 samples were positive with the reference method. The method agreement averaged 96% for the study.

  1. Definitions

2.1 Sensitivity — Rate of sensitivity = (No. of Test Method Positives)/ (No. of Confirmed Positives) x 100

2.2 Specificity— Rate of specificity = (No. of Test Method Negatives)/ (No. of Confirmed Negatives) x 100

2.3 Method Agreement—Method Agreement = [1-(No. of Correct Test Method Results – No. of Correct Reference Method Results/ Total No. of Method Samples)] x 100

2.4 Accuracy — (No. of Confirmed Test Method Positives / Total No. of Reference Method Positives) x 100

  1. Principle

The Strategic Diagnostics Inc. (SDI) RapidChek SELECTSalmonellaTest Kit method is an immunoassay-based test that uses anti-Salmonella spp. antibodies (Abs) and colloidal gold-antibody conjugates incorporated into a lateral flow test strip. The method utilizes 2 proprietary enrichment broths (primary and secondary). Following the primary enrichment (16-22 h, 42C) of the food sample, an aliquot (0.1 mL) is transferred to a tube containing 1 mL of secondary enrichment broth. For raw ground beef, raw ground chicken, and chicken carcass rinsate samples,this is enriched for 16-22 h (42C),whereas for sliced cooked turkey meat and liquid eggs the secondary enrichment is 6-8 h (42C).

Following secondary enrichment, the test strip is placed into the tube containing the secondary enrichment broth. The liquid sample flows through the test strip where it re-hydrates antibody-coated colloidal gold reagents specific to Salmonella spp impregnated in the strip. If antigens are present in the sample, they will bind to the antibody-gold conjugate to form an antigen/antibody complex. As this complex migrates through the nitrocellulose matrix, it passes a zone of anti-Salmonella antibody immobilized on the nitrocellulose membrane (the test line). If antigen is present, the complex is captured in this zone and is visualized by the formation of a red line. A second zone on the membrane (the control line) is designed to capture any antibody-gold complex not bound in the first zone. As a result, when Salmonella antigen is present, the formation of 2 red lines is observed, whereas when Salmonella is not present, only 1 line forms.

This validation report was prepared for claims to detect Salmonella in specific foods including raw ground beef, raw ground chicken, chicken carcass rinsates, sliced cooked turkey meat, and liquid whole eggs using the SDI RapidChek SELECT Salmonella Test Kit method.

  1. General Information

Salmonellaspp. is a gram-negative, facultative anaerobic bacteria of the Enterobacteriaceae family. There are over 2400 known Salmonellaserotypes. Various Salmonellaarenative to the digestive tract of many different animal species and is an important human pathogen. Salmonellahas been implicated as a major cause of human foodborne illnesses worldwide. Each year, this organism is responsible for approximately 1.4 million cases of illness in the United States, 95% of which are contracted through foodborne transmission. Four to six hundred of these typically result in death (1, 2). Clinical symptoms of Salmonellapoisoning vary, ranging from mild gastroenteritis to more serious conditions including septicemia and death.

A variety of foods types have been identified as vehicles of infection for salmonellosis, including raw meat and poultry, fresh produce, processed meats, dairy products and fruit juices. Raw meat and poultry are recognized as one of the most important vehicles of transmission of Salmonella (3, 4). Several control measures have been implemented along food production lines in meat and poultry abattoirs to reduce the levels of Salmonella in these matrices; however, microbiological testing retains a key role in preventing foodborne salmonellosis (5).

  1. Test Kit Information
  2. Kit Name.—RapidChek SELECT Salmonella Test Kit
  3. Catalog Number.—

RapidChek SELECT SalmonellaTest Kit:7000191

RapidChek SELECT Salmonella Primary Enrichment Medium Base: 7000192

RapidChek SELECT Salmonella Secondary Enrichment Medium: 7000193

RapidChek SELECT Salmonella Primary Enrichment Medium Supplement: 7000194

5.3 Ordering Information.—

5.3.1 Strategic Diagnostics Inc.

111 Pencader Drive

Newark, DE19702

Phone: (800) 544-8881

FAX: (302) 456-6782

Web:

5.4 Test Kit Reagents

5.4.1 RapidChekSELECT SalmonellaTest Strips

5.4.2 RapidChekSELECT Salmonella Primary Media. Twenty (20) grams of primary media base was dissolved in 1 liter of deionized water and autoclaved or filter sterilized. Alternatively, media was rehydrated in in sterile deionized water. In this manner, rehydrated media was used within 3 hours of preparation. For chicken carcass rinsates, 40 grams of primary media base was dissolved in 1 liter of deionized water and autoclaved or filter sterilized. Alternatively, media base was rehydrated in sterile deionized water. In this manner, rehydrated media was used within 3 hours of preparation.

5.4.3 RapidChekSELECT Salmonella Supplement. Just prior to use, 10 mL of supplement was added per liter of primary media base. The media was shaken to mix. For chicken carcass rinsates, 20 mLof supplement was added per liter of primary media base and shaken to mix.

5.4.4 RapidChekSELECT Salmonella Secondary Media. Secondary media (73.5 g) was reconstituted in 1 liter of deionized water and boiled with stirring. Alternatively, media was rehydrated in sterile deionized water. In this manner, rehydrated media was used within 3 hours of preparation.

  1. Additional supplies and reagents
  2. Buffered Peptone Water (BPW) - (Difco Becton Dickinson). Twenty (20) grams of media was dissolved in one liter of deionized water and autoclaved for 15 min at 121oC.

6.2TT (Hajna) – (Remel). 91.5g of media was added to one liter of deionized water and brought to a boil. It was allowed to cool to below 50C prior to dispensing into sterile, 10 mL test tubes. Just prior to use, 0.4 mLof iodine-iodide solution (5 g iodine and 8 g potassium iodide in 40 mL deionized water) was added to each tube containing 10 mL of media base.

6.3Rappaport Vassilidis R10 broth (RV) – (Difco Becton Dickinson) 26.6g of media was added to 1 liter of deionized water and heated gently to dissolve. The liquid media was dispensed into 10 mL tubes and autoclaved at 116C for 15 min.

6.4Brilliant green sulfa agar (BGS) – (Remel) 58g of media was added to 1 liter of deionized water and autoclaved for 15 minutes at 121oC.

6.5Xylose Lysine Tergitol 4 agar (XLT4) - (Difco Becton Dickinson) 59g

of media was added to 1 liter of deionized water. Then, 4.6mLof Tergitol 4 (Niaproof 4, Sigma Chemical) was added and the liquid brought to a boil for 1 min.

6.6 Triple Iron Sugar Agar Slant (TSI) - (Becton Dickinson Biosciences)

6.7 Lysine Iron Agar Slant (LIA) – (Becton Dickinson Biosciences)

6.8 API20E kits for identification of Enterobacteriaceae– (BioMerieux)

6.9 SalmonellaPoly O Antisera (A-I, Vi ), Poly H Antisera (a-z, EN-, G-, L-, and Z4-complexes), and Poly Group E1 (Factor 10) Antisera(Becton Dickinson Biosciences)

7.Apparatus

7.1Stomacher bags with filter

7.2Stomacher bags without filter

7.3Inoculating needles and loops

7.4Vortex mixer

7.5Stationary incubator – Capable of holding temperature at 42oC+/- 2.0 for 20-24 hours.

7.6Stationary incubator – Capable of holding temperature at 35oC +/-2.0 for 20-24 hours.

7.7Stomacher – Seward 400 Circulator (Seward, London, England) - for thorough mixing of food samples in enrichment broth.

7.8Top loading balance – To weigh 25 g ( + 0.1g) test samples.

  1. Standard Reference Materials

The following Salmonellastrains were used in the method comparison studies and are available from the American Tissue Type Collection (ATCC, Gaithersburg, MD):

Salmonella Typhimurium ATCC 14028

Salmonella Enteritidis ATCC 13076

Salmonella Kentucky ATCC 9326

Salmonella Anatum ATCC 9270

Additional bacterial strains were used in the Inclusivity and Exclusivity studies and are indicated in Tables1 and 2.

  1. Safety Precautions

Live bacteria may be infectious and pose a significant health hazard. All bacterial cultures should be handled with caution and biohazardous waste should be disposed of appropriately.

  1. General Preparation
  2. Prepare media to be used for the test and reference methods as describe above (Section 6).
  3. Turn on incubators. Control at designated temperatures.
  1. Sample Procurement and Preparation

11.1Raw ground beef, raw ground chicken, liquid eggs, sliced cooked turkey

Food samples were purchased from local grocery stores. Prior to analysis, a portion of raw ground beef, liquid eggs, and sliced cooked turkey were inoculated with Salmonella Typhimurium (ATCC 14028), Salmonella Enteritidis(ATCC 13076), and Salmonella Kentucky(ATCC 9263), respectively, at a target level of 1- 10 CFU/25 g based on cell counting of the inoculum. At a minimum, batches of inoculated food samples were of sufficient size to produce 40 duplicate samples on subdivision for the particular method comparison study (approx. 1 kg) as well as a 3 tube, 4 dilution Most Probable Number (MPN) analysis (approx. 400 g) that was conducted on all batch inoculated matrices. Inoculated samples were subsequently refrigerated 48 to 72 hrsprior to analysis in order to acclimate the inoculum in the food sample.

Raw ground chicken was not inoculated due to the relatively high frequency of natural contamination. Raw ground chicken was tested on the same day of purchase.

11.2Chicken carcass rinsates

Whole chicken carcasses werepurchased from a local grocery store. A modified carcass rinsate procedure was used in order to accommodate MPN analysis at low inoculation levels. The carcass was initially rinsed with 600 mL of BPW. This initial rinsate served as the negative control and was immediately refrigerated until analysis (48 to 72 hrs). After the initial rinse, the carcass was inoculated with a Group E1Salmonella Anatum(ATCC 9270) at a target level of 1- 10 CFU/ 30 mL of rinsate and Citrobacter braakii(ATCC 51113) at a target level 20 times higher than the Salmonella target level based on inoculum cell counts. The inoculated carcass was refrigerated for 48 to 72 hrs prior to analysis in order to acclimate the inoculum in the food sample. After refrigeration, the carcass was rinsed with 2000 mL of BPW by hand shaking for 1 min. This rinsate was used as the inoculated sample and for MPN analysis.

11.3Enrichment procedures

11.3.1Raw ground beef, raw ground chicken, liquid eggs, sliced cooked turkey

In order to conduct the sample enrichment procedure, the RapidChek SELECT primary enrichment broth (5.1.2-5.1.3) was pre-warmed at 42ºC for 20 minutes prior to use. For raw ground beef, raw ground chicken, liquid eggs, and sliced cooked turkey, 25 g wasplaced into a sterile stomacher bag followed by 225 mL of RapidChek SELECT primary enrichment broth. The sample was stomached and incubated for 16-22 h at 42C +/- 2.0oC. Then, 0.1 mL of this enrichment broth was transferred to a 12 x 75 mm tube containing 1.0 mL of RapidChek SELECT secondary enrichment broth(5.1.4) and incubated for an additional 6-8 hrs (liquid eggs and sliced cooked turkey) or 16-22 h (raw ground beef and raw ground chicken) at 42C +/- 2.0oC.

11.3.2Chicken carcass rinsates

For chicken carcass rinsate samples, 30 mL of rinsate was placed into a sterile stomacher bag followed by 30 mL of 2X RapidChek SELECT primary enrichment broth(5.1.2-5.1.3). The sample was shaken to mix and incubated for 16-22 h at 42C +/- 2.0oC. Then, 0.1 mL of this enrichment broth was transferred to a 12 x 75 mm tube containing 1.0 mL of RapidChek secondary enrichment broth (5.1.4) and incubated for an additional 16-22 h at 42C +/- 2.0oC.

  1. Analysis

Following the secondary enrichment, one RapidChek SELECT test strip was placed into the tube and allowed to develop 10 min. After 10 min, the strip was removed from the tube and observed.

13. Interpretation and Test Result Report

Upon observation of the test strip, the appearance of one (1) red line (the control line) indicates that the sample is negative for Salmonella spp. The appearance of two (1) red lines (test line and control line) indicates that the sample is presumptively positive for Salmonella spp. and should be confirmed.

14. Internal Validation Studies

14.1Inclusivity

14.1.1 Methodology

Salmonella single colony isolates were cultured in 10 mL of RapidChek SELECT primary enrichment media for 16-22 hr at 42C. Then, 0.1 mL of the primary broth was transferred to 1 mL of RapidChek SELECT secondary enrichment media. This was incubated at 42C for 16-22 hr. Following enrichment, a test strip was inserted into the tube and developed for 10 min after which time the test strip was read and interpreted as previously described (section 14).

14.1.2 Results

Table 1 shows the results from the Inclusivity study.

Table 1. Results from the Inclusivity Study.

Serogroup / Serovar and strain / Source / Test Reactivity / Serogroup / Serovar and strain / Source / Test Reactivity
A / S. Paratyphi A ATCC 9150 / Not known / + / C2 / S. Muenchen ATCC 8388 / Human / +
B / S. Agona USDA A341-11 / Not known / + / C2 / S. Newport ATCC 6962 / Human / +
B / S. Agona ATCC 51957 / Human / + / C2 / S. NewportUSDA 1275 / Food / +
B / S. Agona NFC 1035: S-R2 / Food / + / C3 / S. Albany ATCC 51960 / Human / +
B / S. Brandenburg ARS 21 / Drag swab / + / C3 / S. Amherstiana DSM 006 / Food / +
B / S. Brandenburg ARS 20 / Chicken Feces / + / C3 / S. Kentucky DSM 7-19 / Litter / +
B / S. Brandenburg DSM 15 / Not known / + / C3 / S. Kentucky ARS 25 / Litter / +
B / S. Brandenburg USDA-MFS 9190 / Food / + / C3 / S. Kentucky ARS 26 / Environmental / +
B / S. Bredeney DSM 04 / Food / + / C3 / S. Kentucky ATCC 9263 / Poultry / +
B / S. Derby ATCC 6960 / Pork / + / C3 / S. Kentucky DSM 6-290 / Food / +
B / S. Heidelberg ATCC 8326 / Not known / + / C3 / S. Kentucky DSM 7-147 / Chicken / +
B / S. Heidelberg WVU 5F114 / Litter / + / C3 / S. Kentucky DSM 76-P / Litter / +
B / S. Heidelberg WVU 5F140 / Litter / + / C3 / S. Kentucky DSM 7-82 / Drag swab / +
B / S. Heidelberg WVU 5F128 / Feed / + / C3 / S. Virginia DSM 145 / Food / +
B / S. Heidelberg WVU 5F155 / Feed / + / C4 / S. Jerusalem Tyson 25 / Food / +
B / S. Heidelberg WVU 6F71 / Swab / + / D1 / S. Dublin ATCC 15480 / Human / +
B / S. Paratyphi B ATCC 19940 / Human / + / D1 / S. Enteritidis ARS 12 / Litter / +
B / S. Paratyphi B ATCC M4-00-02932 / Human / + / D1 / S. Enteritidis ATCC 13076 / Human / +
B / S. sp #28 / Turkey / + / D1 / S. Enteritidis ATCC 8391 / Human / +
B / S. Saintpaul ATCC 9712 / Human / + / D1 / S. Enteritidis M1 BGA 164-93 / Not known / +
B / S. Saintpaul FSIS 051 / Food / + / D1 / S. Enteritidis Tyson 22 / Food / +
B / S. Stanley DSM 305 / Not known / + / D1 / S. Gallinarum ATCC 9184 / Not known / +
B / S. Tyhimurium ATCC 23564 / Human / + / D1 / S. Javiana ATCC 10721 / Human / +
B / S. Typhimruium ATCC 19585 / Not known / + / D1 / S. Panama Tyson 3 / Food / +
B / S. Typhimurium ARS 3 / Water / + / D1 / S. Typhi (Keystone) / Human / +
B / S. Typhimurium ATCC 14028 / Chicken / + / D2 / S. Maarsen ATCC 15793 / Lizard / +
B / S. Typhimurium ATCC 23555 / Not known / + / E1 / S. Anatum WVU 5F28 / Waterers / +
B / S. Typhimurium ATCC 23566 / Human / + / E1 / S. Anatum WVU 5F29 / Waterers / +
B / S. Typhimurium ATCC 23595 / Human / + / E1 / S. Anatum ATCC 9270 / Pork / +
B / S. Typhimurium ARS 1 / Chicken Feces / + / E1 / S. London DSM 80 / Food / +
B / S. Typhimurium ATCC 23853 / Human / + / E1 / S. Muenstar WVU 5F22 / Swabs / +
B / S. Typhimurium ATCC 25241 / Human / + / E1 / S. Muenstar WVU 8F3 / Poultry / +
B / S. Typhimurium ATCC 7823 / Not known / + / E1 / S. Muenstar WVU 8F9 / Feces / +
B / S. Typhimurium DSM 124-193 / Human / + / E1 / S. Muenster WVU 5F24 / Litter / +
B / S. Typhimurium DSM 126-193 / Human / + / E1 / S. Muenster WVU 5F30 / Environmental / +
B / S. Typhimurium ARS 2 / Chicken carcass rinse / + / E2 / S. Newbrunswick DSM 92 / Food / +
B / S. Typhimurium DSM 129-204 / Human / + / E2 / S. Newington ATCC 29628 / Ducklings / +
B / S. Typhimurium ATCC 23594 / Not known / + / E4 / S. Senftenburg WVU 6F1 / Feed / +
C1 / S. Paratyphi C ATCC 13428 / Human / + / E4 / S. Senftenburg WVU 6F11 / Litter / +
C1 / S. Branderup DSM 16 / Not known / + / E4 / S. Senftenburg ARS 8 / Water / +
C1 / S. Cholerasuis Tyson 18 / Chicken / + / F / S. Abaetetuba ATCC 35640 / Creek water / +
C1 / S. Infantis ARS 22 / Environmental / + / F / S. Rubislaw Tyson 21 / Litter / +
C1 / S. Infantis ATCC 51741 / Pasta / + / G1 / S. Clifton DSM 38 / Food / +
C1 / S. Livingstone M7 00-02940 / Animal feces / + / G1 / S. Poona ARS 119 / Not known / +
C1 / S. Mbandaka Tyson 23 / Food / + / G1 / S. Poona ARS 121 / Food / +
C1 / S. Montevideo ARS 31 / Litter / + / G1 / S. Poona DSM 109 / Food / +
C1 / S. Montevideo ARS 32 / Feces / + / G1 / S. Poona DSM 338 / Human / +
C1 / S. Montevideo ARS 33 / Feces / + / G2 / S. Cubana 12007-02 / Not known / +
C1 / S. Oranienburg ATCC 9239 / Human / + / G2 / S. Grumpensis DSM 333 / Food / +
C1 / S. Thompson ARS 13 / Litter / + / G2 / S. Wichita DSM 147 / Food / +
C1 / S. Thompson ARS 14 / Feces / + / G2 / S. WorthingtonWVU 6F14 / Not known / +
C1 / S. Thompson ARS 15 / Drag swab / + / G2 / S. Worthington WVU 6F15 / Food / +
C1 / S. Thompson ATCC 8391 / Human / + / G2 / S. Worthington ARS 146 / Not known / +
C2 / S. Blockley DSM14 / Food / + / H / S. Boecker DSM 19 / Not known / -
C2 / S. Hadar ATCC 51956 / Not known / + / I / S. Hvittingfoss DSM 070 / Not known / +
C2 / S. Hadar FSIS 044 / Human / + / K / S. Cerro Tyson 9 / Food / +
N / S. Urbana ATCC 9261 / Not known / -

One hundred and thirteen (113) Salmonella isolates representing 18 somatic antigen serogroups were tested. The test reacted to all but 2 isolates. This represents a sensitivity of 98.2%.

14.2Exclusivity

15.3.1Methodology

Single colony isolates of non-Salmonellae bacteria werecultured in 10 mL of Brain Heart infusion broth (BHI) incubated at 37C for 24 h. One (1) mL of the broth culture was transferred toa 12 x 75 mm tube and a test strip inserted into the tube. The test strip was read and interpreted as previously described (section 14).

15.3.2Results

Table 2 shows the results from the Exclusivity study.

Table 2. Results from the Exclusivity Study.

Species and strain designation / Test Reactivity / Species and strain designation / Test Reactivity
Aeromonas hydrophila #10 / - / Escherichia coli ATCC 51755 / -
Aeromonas hydrophila #8 / - / Escherichia coli O106 / -
Aeromonas veronii 9071 / - / Escherichia coli O129 / -
Aeromonas veronii ATCC 51106 / - / Escherichia coli R7-32C4 / -
Citrobacter braakii ATCC 51113 / - / Hafnia alvei ATCC 25927 / -
Citrobacter diversus 130R2 / - / Klebsiella pneumoniae #9 / -
Citrobacter farmeri ATCC 51112 / - / Klebsiella pneumoniae 107G6 / -
Citrobacter freundii ATCC 8090 / - / Klebsiella pneumoniae ATCC 13882 / -
Citrobacter freundii 35 / - / Morganella morganii L9-8.2 / -
Citrobacter koseri ATCC 27026 / - / Morganella morganii L13-8.2 / -
Citrobacter sedlaki ATCC 51115 / - / Proteus mirabilis 68 / -
Citrobacter werkmanii ATCC 51114 / - / Proteus mirabilis 70 / -
Citrobacter youngae ATCC 11102 / - / Proteus mirabilis ATCC 14153 / -
Enterobacter aerogenes ATCC 15038 / - / Proteus mirabilis ATCC 4630 / -
Enterobacter agglomerans 107b4 / - / Proteus sp. CW38 / -
Enterobacter agglomerans oc44 / - / Proteus vulgaris #19R7 / -
Enterobacter cloacae #2 / - / Proteus vulgaris 6380 / -
Enterobacter cloacae ATCC 13047 / - / Proteus vulgaris 8427 / -
Enterobacter cloacae ATCC 27508 / - / Pseudomonas aeruginosa 112-1 / -
Escherichia coli 111-1 / - / Pseudomonas fluorenscens ATCC 49838 / -
Escherichia coli 96C5 / - / Shigella sp. 24/11-7.3 / -
Escherichia coli 99G1 / - / Shigella sp. ATCC 23354 / -
Escherichia coli ATCC 11775 / - / Vibrio metschnikovii 62A2 / -
Escherichia coli ATCC 35218 / - / Vibrio sp. 62A1 / -
Escherichia coli ATCC 35421 / - / Vibrio sp. 62A12 / -

Fifty non-Salmonella bacterial isolates representing 11 genera commonly found in food were grown for 24 hrs in non-selective media and , in all cases, a highly turbid culture (approximately 1 x 108 to 1 x 109 CFU/mL) resulted. They were then tested with the test strip. None of the isolates reacted with the test. This represents a selectivity of 100%.