Enumeration of Salmonellae by Most-Probable-Number Using the Salmonella 1–2 Test

Abstract

A rapid Salmonella identification test was substituted for the selective plating and identification steps in the standard cultural most-probable-number procedure. The modified procedure was evaluated using a mixed culture of four salmonellae species inoculated into ground beef. The rapid test kit was inoculated from both the pre-enrichment and selective enrichment steps in the standard procedure. There were fewer false negatives when the test kits were inoculated from selective vs. non-selective broths. However, there were no false negatives when the kit was inoculated from Rappaport-Vassiliadis' broth, after pre-enrichment in lactose broth. Use of the test kit in the MPN procedure produced acceptable results in 48 to 72 h, compared with 96 to 120 h for the standard procedure.