Detection of Salmonella in Alfalfa Sprouts by Reverse TranscriptasePolymerase Chain Reaction

Detection of Salmonella in Alfalfa Sprouts by ReverseTranscriptase Polymerase Chain Reaction

2002FDA Science Forum

FDA:Building a Multidisciplinary Foundation

February20-21, 2002

WashingtonConvention Center, Washington, DC

PosterAbstracts, Board T-06

Grisselle Martinez, Karlygash M. Yermukan, ORA, FDA,Alameda, CA

A fast and reliable method for the detection of live Salmonellacells in alfalfa sprouts using reverse transcriptase PCR was developed duringthis study. Total RNA was isolated from sprout samples spiked with Salmonella.The ST11 and ST15 primers, Aabo et al. were used to amplify a 429 bp-longfragment during RT-PCR. The resulting DNA fragment was isolated and sequenced.This method was also tested using sprouts homogenate spiked with Salmonella andnaturally contaminated sprouted seeds cells. The detection limit was ~10³– 10⁴ cells. The estimated time of completion for the rinse, RNAisolation, RT-PCR and gel electrophoresis was 6 hours for 5-10 samples. Theadvantages of this method over the currently used rapid method, are: a) thedetection of live (vs. non-viable) cells, b) the procedure is completed in asignificantly shorter period of time.