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Title: Salmonella attribution and clonal dissemination

item Frye, Jonathan
item Cray, Paula

Submitted to: USDA Annual Food Safety Research Planning Meeting
Publication Type: Proceedings
Publication Acceptance Date: 2/22/2007
Publication Date: 2/22/2007
Citation: Frye, J.G., Boyle, D.S., Kim, S., Gautom, R., Hu, J., Cray, P.J. 2007. Salmonella attribution and clonal dissemination. USDA Annual Food Safety Research Planning Meeting. February 21-23,2007. Shepherdstown, WV.

Interpretive Summary:

Technical Abstract: Background: The bacterial species Salmonella enterica is one of the major causes of gastroenteritis in humans and has over 1,500 serotypes. Serotyping is the most common tool used to identify isolates from diseased patients. However, the serotyping method can takes several weeks and sometimes can be impossible to perform. Presently, serotyping of Salmonella enterica is performed only at state and national reference laboratories because it requires skilled staff and requires a stock of many commercial antisera. In this study we demonstrate the potential of multiplex PCR to create an extremely rapid and accurate method to serotype the 31 most common serotypes of Salmonella enterica in WA State. Methods: Primers for two 5-plex PCR reactions were selected for target genes in the Salmonella enterica serovar Typhimurium LT2 and Salmonella enterica serovar typhi CT18 genomes. Results: A total of 253 specimens from 31 different serotypes including the top 20 clinical and top 10 veterinary serotypes were screened with the assay. From this data, unique amplification profiles for almost all of 31 Salmonella enterica serotypes were established. Other PCR assays were developed for further discrimination of similar serotypes when necessary. From 110 isolates screened by blind testing 102 isolates were correctly typed using this method. This is comparable with serotyping. Conclusions: Here we demonstrate a very rapid and simple molecular method for serotyping common Salmonella enterica serotypes. The time for serotyping is dramatically reduced to only 5 hours. The method is basic and does not need specialized staff and a large collection of antisera. The assay may be applied in any clinical facility which has PCR and electrophoresis equipment.