Reliability of the Immunodiffusion 1–2 Test™ System for Detection of Salmonella in Foods

Abstract

The novel 1–2 Test™ is a self-contained tetrathionate enrichment and immunodiffusion-agglutination reaction vial for the detection of Salmonella in preenrichment and direct enrichment cultures of processed and non-processed foods, respectively. Of 186 foods tested, 46 (24.7%) were found to contain salmonellae by all analytical conditions combined. The standard cultural procedure identified 43 (93.5%) contaminated samples whereas the 1–2 Test™ system detected 20 (43.5%) and 25 (54.3%) positive samples after 8 h and 24 h of incubation, respectively. Although six false-positive reactions were obtained after short (8 h) incubation of test vials, homologous reactions were not detected after 24 h incubation. System deficiency likely stems from the low selectivity of applied cultural conditions and inability of the 1–2 Test™ to detect salmonellae in the presence of large numbers of competing microflora.