Comparison of Assurance Gold Salmonella EIA BAX for Screening Salmonella and GENE TRAK Salmonella DLP Rapid Assays for Sprouts

Comparison of Assurance Gold SalmonellaEIA, BAX forScreening/Salmonella, and GENE-TRAK Salmonella DLP Rapid Assays for Detection ofSalmonellain Alfalfa Sprouts and Sprout Irrigation Water

Diana S. Stewart, Karl F. Reineke, and Mary L. Tortorello

U.S. Food and Drug Administration, National Center for FoodSafety and Technology, 6502 S. Archer Rd., Summit-Argo, IL 60501

The Assurance Gold Salmonella EIA, BAX forScreening/Salmonella, and GENE-TRAK Salmonella DLP rapid assays were comparedwith official cultural methods described in the Bacteriological AnalyticalManual (BAM) for analysis of alfalfa sprouts and sprout irrigation water forthe presence of Salmonella.  Thelower limits of detection of 4 serovars of Salmonella cells (S.Tennessee, S. muenchen, S. mbandanka, and S. cubana) in pure culture weredetermined as approximately log10 2, 5, and 6 for the BAX, GENE-TRAK,and Gold EIA, respectively.  Despiteits low detection limit, the BAX did not perform as well as the other assays inanalyzing contaminated sprouts and sprout irrigation water. For 4 different lots of sprouts and sprout irrigation water samplesinoculated with the 4 serovars at low [102 colony forming units (CFU/g)] andhigh (68-180 CFU/g) levels, the BAX detected Salmonella in 58/64 (0.6%)of the samples, compared with 64/64 (100%) by the GENE-TRAK, Gold EIA, and BAMmethods.  Assay performance was alsocompared for analysis of naturally contaminated sprouts and sprout irrigationwater with 3 lots of alfalfa sprouted seeds associated with differentsalmonellosis outbreaks.  Positiveassay results for the naturally contaminated samples were Gold EIA 41, GENE-TRAK36, BAM 33, and BAX 13.