The outbreak strain has been isolated from an opened 5-pound container of King Nut brand peanut butter in Minnesota.

Further tests are pending to determine if this Salmonella is the outbreak strain.

The real thing here is to see if the strain type matches up with the outbreak strain.

Investigators have also isolated the outbreak strain of E. coli O157:H7 from leftover steak consumed by an infected child.

This may lead to better control of outbreak strains.

As of November 30, 2011, 60 persons infected with the outbreak strain of E. coli serotype O157:H7 have been reported from 10 states.

As of December 4, 2011, 60 persons infected with the outbreak strain of E. coli O157:H7 have been reported from10 states.

Through genetic testing this positive sample was found to be indistinguishable from the outbreak strain, using pulsed-field gel electrophoresis with two enzymes.

Through genetic testing this positive sample is indistinguishable from the outbreak strain, using pulsed-field gel electrophoresis with one enzyme.

Whenever possible, trace-back is confirmed by comparison of the outbreak strain with isolates obtained from the primary source.