Rapid Salmonella Detection in Foods by Motility Enrichment on a Modified Semi-Solid Rappaport-Vassiliadis Medium

Abstract

Modification of Rappaport-Vassiliadis enrichment broth into a semisolid motility medium (MSRV) provided a sensitive means for detecting Salmonella in contaminated foods. The type of peptone, the concentration of magnesium chloride, the presence of novobiocin and the temperature of incubation were determinants in medium performance. The analytical procedure consists of preenrichment for 20 h, followed by motility enrichment on MSRV for 24 h and, if there is migration, serological tests with the motile culture. The test result is obtained within 48 h from the start of preenrichment. This approach gave 39% more Salmonella-positive samples than enrichment in tetrathionate brilliant green broth with subsequent plating.