So now that you've identified which bacterium caused the food poisoning, you decide to look for the bacterium in the food at different locations around campus. The best way to do this is to obtain a nucleic acid probe and test the foods directly for the presence of the bacterium. A technique termed FISH (Fluorescent In-Situ Hybridization) takes advantage of the specificity of nucleic acid pair hydrogen bonding (ie. A-T; C-G). FISH utilizes a short sequence of nucleotides (the probe) which is complementary to a UNIQUE sequence of nucleotides in the bacterium in question. The probe can be tagged with a fluorescent marker which is readily visible under a fluorescent microscope. Therefore, where the probe binds to its complementary sequence in the bacterium, a fluorescent signal will be seen, indicating the presence of the bacterium for which the probe was specifically designed.
From your previous tests and results, you should know which bacterium you should be looking for. Which one probe do you want to purchase (budget cuts again!)?
Nucleic acid probe for Shigella.
Nucleic acid probe for Salmonella.