Microbial pathogens have been estimated, in a study published in 1999, to cause about 76 million cases of foodborne illnesses annually in the United States, including an estimated 325,000 and 5,000 cases that result in hospitalizations and deaths, respectively (Mead et al., 1999). A better understanding of foodborne disease transmission, including accurate estimates of attribution of foodborne illnesses to sources, are sorely needed to improve our ability to better control and prevent foodborne …

Figure 2. (a) Picture of a pulsed field gel electrophoresis (PFGE) agarose gel for Salmonella isolates digested with XbaI. Lanes 1, 7, and 15 represent digested DNA from the control strain Salmonella ser. Braenderup (H9812), which is used as the marker (denoted by M in the gel image) for bioinformatics analysis. Lanes 2–6 and 8–12 represent 12 Salmonella test isolates characterized by PFGE typing. (b) Dendogram of PFGE banding patterns for Salmonella test isolates 1–12 normalized using BioNumerics software.

Figure 3. Depiction of (a) the national PulseNet molecular subtyping network for foodborne disease surveillance and (b) the international PulseNet network for foodborne disease surveillance. Figures 3a and b were provided by Peter Gerner-Smidt, CDC.

Figure 4. Concept and workflow of multilocus variable number tandem repeat (MLVA) typing, including hypothetical variable number tandem repeats (VNTRs) for two isolates and hypothetical agarose gel electrophoresis to separate VNTRs amplified for those isolates. Lanes in the hypothetical agarose gel electrophoresis image from left to right include a DNA marker (designated M, where larger fragments are found at the top of the gel and smaller fragments are at the bottom of the gel) in lane 1 and size of VNTRs 1–3 for isolates A and B in lanes 2–7.

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