Evaluation of the VITEK 2 gram positive (GP) microbial identification test card: collaborative study.

A collaborative study was conducted to evaluate the performance of the VITEK 2 Gram Positive (GP) identification card for use with the VITEK 2 automated microbial identification system. The GP test card is used in the identification of selected Gram positive organisms, including Listeria and Staphylococcus species. The VITEK 2 GP card is based on 43 biochemical tests measuring carbon source utilization, inhibition and resistance, and enzymatic activities. A total of 20 laboratories representing government, industry, and private testing laboratories throughout the United States participated. In this study, 720 Gram-positive inclusivity isolates were analyzed by the GP Identification method. Of the 720 well-characterized isolates, 714 were identified correctly, zero were misidentified, zero were unidentified, and six were not characterized as a Gram-positive organism by the VITEK 2 GP method. Additionally, 120 strains exclusive of Gram-positive organisms were screened by Gram stain. A total of 106 isolates were correctly excluded. Fourteen organisms were incorrectly characterized by Gram stain procedures, thus resulting in improper analysis and misidentification by VITEK GP. The VITEK 2 GP identification method is an acceptable automated method for the rapid identification of selected Gram-positive bacteria.

Evaluation of the VITEK 2 Gram-negative (GN) microbial identification test card: collaborative study.

A collaborative study was conducted to evaluate the performance of the VITEK 2 Gram-negative (GN) Identification card for use with the VITEK 2 automated microbial identification system. The GN test card is used in the identification of fermenting and nonfermenting Gram-negative bacilli, including the select agent organisms Brucella melitensis, Francisella tularensis, Burkholderia mallei, B. pseudomallei, and Yersinia pestis. The VITEK 2 GN card is based on 47 biochemical tests measuring carbon source utilization, inhibition and resistance, and enzymatic activities. A total of 20 laboratories representing government, industry, and private testing facilities throughout the United States participated. In this study, 720 Gram-negative inclusivity isolates were analyzed by the GN Identification method. Of the 720 well-characterized isolates, 707 were identified correctly, 0 were misidentified, 0 were unidentified, and 13 were not characterized as a Gram-negative organism. Additionally, 120 isolates exclusive of fermenting and nonfermenting Gram-negative bacilli were screened by Gram stain. A total of 117 isolates were correctly excluded. Three organisms were incorrectly characterized by Gram stain procedures, resulting in incorrect analysis and misidentification by VITEK 2 GN. The VITEK 2 GN identification method is an acceptable automated method for the rapid identification of Gram-negative bacteria.

Evaluation of VIDAS Salmonella (SLM) easy Salmonella method for the detection of Salmonella in a variety of foods: collaborative study.

The VIDAS Salmonella (SLM) Easy Salmonella method is a specific enzyme-linked fluorescent immunoassay performed in the automated VIDAS instrument. The VIDAS Easy Salmonella method is a simple 2-step enrichment procedure, using pre-enrichment followed by selective enrichment in a newly formulated broth, SX2 broth. This new method was compared in a multilaboratory collaborative study to the U.S. Food and Drug Administration's Bacteriological Analytical Manual, Chapter 5 method for five food matrixes (liquid egg, vanilla ice cream, spinach, raw shrimp, and peanut butter) and the U.S. Department of Agriculture's Microbiology Laboratory Guidebook 4.04 method for deli turkey. Each food type was artificially contaminated with Salmonella at three inoculation levels. A total of 15 laboratories representing government, academia, and industry, throughout the United States, participated. In this study, 1583 samples were analyzed, of which 792 were paired replicates and 791 were unpaired replicates. Of the 792 paired replicates, 285 were positive by both the VIDAS and reference methods. Of the 791 unpaired replicates, 341 were positive by the VIDAS method and 325 were positive by the cultural reference method. A Chi-square analysis of each of the six food types was performed at the three inoculation levels tested. For all foods evaluated, the VIDAS Easy SLM method demonstrated results comparable to those of the reference methods for the detection of Salmonella.

TEMPO EC for the enumeration of Escherichia coli in foods: collaborative study.

The automated method for enumeration of Escherichia coli, TEMPO EC, in foods uses a dehydrated culture medium and enumeration card containing 48 wells across three different dilutions for the automatic determination of the most probable number (MPN). The alternative method was compared in a multilaboratory collaborative study to AOAC Official Method 966.24. Six food types were artificially contaminated with E. coli: raw ground beef, bagged lettuce, cooked chicken, pasteurized crabmeat, frozen green beans, and pasteurized whole milk. All foods were analyzed for E. coli counts by 11 collaborating laboratories throughout the United States. Test portions from the six food types each contaminated at four different contamination levels were evaluated. The study demonstrated that the TEMPO EC method is a reliable, automated assay for the enumeration of E. coli in foods.