In 1999, several states reported clusters of Salmonella Newport, an antibiotic resistant strain of the bug, with an indistinguishable PFGE pattern and the same anti-microbial resistance pattern. The states reported to PulseNet, the national database for foodborne disease surveillance, which prompted an investigation into the cause of the outbreak.
In the investigation, health officials found that 7 out of 8 people in the clusters had eaten ground beef within several days before the onset of illness. Ultimately, the investation identified a single producer that had distributed the contaminated meat to grocery stores, and an unopened package of ground beef ultimately tested positive for the outbreak strain of Salmonella Newport. Investigators also found that, from 1997-1999, 1% of all Salmonella in meat processing facilities was Salmonella Newport.