Molecular surveillance of shiga toxigenic Escherichia coli O157 by PulseNet USA.

PulseNet USA is the national molecular subtyping network system for foodborne disease surveillance. Sixty-four public health and food regulatory laboratories participate in PulseNet USA and routinely perform pulsed-field gel electrophoresis of Shiga toxigenic Escherichia coli isolated from humans, food, water, and the environment on a real-time basis. Clusters of infection are detected in three ways within this system: through rapidly alerting the participants in the electronic communication forum, the PulseNet Web conference; through cluster analysis by the database administrators at the coordinating center at the Centers for Disease Control and Prevention of the patterns uploaded to the central server by the participants; and by matching profiles of strains from nonhuman sources with recent human uploads to the national server. The strengths, limitations, and scope for future improvements of PulseNet are discussed with examples from 2002. In that year, notices of 30 clusters of Shiga toxigenic E. coli O157 infections were posted on the Web conference, 26 of which represented local outbreaks, whereas four were multistate outbreaks. Another 27 clusters were detected by central cluster detection performed at the Centers for Disease Control and Prevention, of which five represented common source outbreaks confirmed after finding an isolate with the outbreak pattern in the implicated food. Ten food isolates submitted without suspicion of an association to human disease matched human isolates in the database, and an epidemiologic link to human cases was established for six of them.

The Wisconsin State Laboratory of Hygiene and emerging enteric pathogens.

At the turn of the 20th century, typhoid fever was common in Wisconsin, and was a major impetus for the establishment of the Wisconsin State Laboratory of Hygiene (WSLH) in 1903. By the 1940s, typhoid was virtually eliminated in the United States due to public health measures such as disinfection of drinking water, sewage treatment, pasteurization, and shellfish bed sanitation. However, new food and waterborne pathogens have emerged to take the place of Salmonella Typhi. Infections with non-typhoidal Salmonella strains in the United States have increased almost 10-fold since the 1950s. In the last 20 years, the emergence of foodborne pathogens, such as Escherichia coli O157:H7, Cyclospora cayetanensis, Noroviruses (Norwalk-like viruses), Cryptosporidium parvum, Campylobacter jejuni, Yersinia enterocolitica, and multi-drug-resistant Salmonella, has identified a need for accurate laboratory diagnosis of enteric disease and outbreaks.

Four strains of Escherichia coli O157:H7 isolated from patients during an outbreak of disease associated with ground beef: importance of evaluating multiple colonies from an outbreak-associated product.

This report describes the investigation of a ground-beef-associated outbreak that involved five genetically distinct patient strains of Escherichia coli O157:H7. Human and product isolates were evaluated by pulsed-field gel electrophoresis (PFGE) with two endonucleases. The multiple-strain etiology of this outbreak underscores the importance of isolating and evaluating multiple colonies from outbreak-related products and comparing two endonuclease PFGE patterns of all product and human isolates identified during outbreak periods. This investigation emphasizes the importance of interviewing all confirmed and suspected case patients during the outbreak period, regardless of the PFGE pattern of their isolate, to confirm or rule out an epidemiologic link to the outbreak.