The Centres for Disease Control and Prevention is beginning a programme to outsmart food outbreaks by routinely decoding the bugs' DNA.
First up is listeria, bacteria especially dangerous to pregnant women.
Federal and state officials are sequencing the genomes of all the listeria infections diagnosed in the US this year, along with samples found in tainted foods or factories.
It's the first time the technology has been used for routine disease surveillance, looking for people with matching strains who may have gotten sick from the same source.
CDC Director Dr Tom Frieden calls it a new, more precise way to find and fight infections.