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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Analysis of Poultry-Associated Salmonella enterica to Identify and Characterize Properties and Markers Associated with Egg-Borne Transmission of Illness

Location: Egg Safety and Quality

Title: Evaluation of a dkgB linked intergenic sequence ribotyping (ISR) method for assigning serotype to Salmonella enterica isolated from poultry environmental samples.

Authors
item Lungu, Bwalya -
item Sanchez-Ingunza, Roxana -
item Guard, Jean

Submitted to: American Association of Avian Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: December 27, 2012
Publication Date: July 20, 2013
Citation: Lungu, B., Sanchez-Ingunza, R., Guard, J.Y. 2013. Evaluation of a dkgB linked intergenic sequence ribotyping (ISR) method for assigning serotype to Salmonella enterica isolated from poultry environmental samples. American Association of Avian Pathologists. p. 13.

Technical Abstract: The Kauffman White (KW) serotyping method requires more than 250 antisera to characterize more than 2,500 Salmonella serovars. The complexity of serotyping could be overcome using molecular methods. In this study, a dkgB-linked intergenic sequence ribotyping (ISR) method that generates sequence occurring within and around one ribosomal region of the Salmonella enterica genome was applied. A group of 248 suspected Salmonella isolates obtained from poultry environmental samples was evaluated. The ISR method correctly assigned serotype to 228/248 (91.9%) of the isolates, and this group included 21 isolates (8.5%) that could not be assigned serotype by KW. 20/248 (8.1%) of the isolates were not Salmonella. Of the 227 isolates assigned serotype by ISR, 151/227 (67%) isolates had matching serotypes between the ISR and KW methods. However, 76/227 (33%) isolates had disagreement. Conflicts between ISR and KW suggest the cultures from which the test isolates were obtained may have been mixed at time of storage. Storing samples by freezing appeared to impact results in two ways, namely by increasing the number that could not be serotyped by the KW method and the incidence at which mixtures may yield an alternative serotype. In addition to high specificity and sensitivity, ISR is faster, cheaper and less time-consuming than traditional serotyping. Overall, the results suggest that the ISR method is an alternative tool to the Kauffman White method for serotyping and differentiating between the various Salmonella enterica serotypes isolated from the poultry environment.

Last Modified: 10/30/2014
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