Use of Pulsed-Field Gel Electrophoresis of Conserved XbaI Fragments for Identification of Swine Salmonella Serotypes

Abstract

Swine Salmonella isolates (n ‫؍‬ 674) from various locations throughout the United States and Canada were analyzed via pulsed-field gel electrophoresis (PFGE) with XbaI. PFGE subtypes were analyzed by cluster analysis and compared to conventional serotyping results. The analysis showed a correlation of serotype to PFGE subtype. In addition, conserved fragments were identified within the restriction patterns that were unique to each serotype. PFGE using XbaI restriction provided a possible alternative method for screening and identifying swine Salmonella serotypes.

Comparison of Typing Methods with a New Procedure Based on Sequence Characterization for Salmonella Serovar Prediction

“…5Ϫ. This is consistent with recent studies (16,47) that also showed that the majority of isolates for which serovars were not correctly predicted by PFGE belonged to S. 4,5,12:i:Ϫ; in one study, 135 misclassified S. 4,5,12: i:Ϫ isolates were predicted to either be S. Typhimurium (95 isolates) or S. Typhimurium var. 5Ϫ (40 isolates) (16).…”

“…For banding-pattern-based subtyping methods, the ability to correctly predict serovars ranged from 65% to 76% for isolates representing the 40 most common Salmonella serovars, and by comparison, MLST correctly predicted the serovars of 91% of these isolates. Previous studies typically only tested the ability of one or a few subtyping methods to predict serovars in isolates representing limited diversity and a small number of serovars (19,21,22,(46)(47)(48). For example, Gaul et al (47) compared one banding-pattern method, PFGE, to traditional serotyping on a collection of 674 swine Salmonella isolates.…”

Evaluation of Pulsed-Field Gel Electrophoresis Profiles for Identification of Salmonella Serotypes

“…Additionally, based on the study results, unsupervised cluster analysis can provide clues to serotype identity and supervised classification analysis then complements these results to provide further serotype confirmation. These conclusions concur with those of Gaul et al (7), who suggested that "when unable to serotype by conventional methods, PFGE would be a possible alternative in serotype determination or may be used to screen isolates for possible serotypes before actual serotyping." While the results presented in this study include representatives of the top 5 Salmonella serovars associated with human disease in the United States (http://www.cdc.gov/ncidod/dbmd/phlisdata /salmtab/2006/SalmonellaTable1_2006.pdf), further predictive models that may be developed based on a larger data set, including more isolates representing various serotypes involved in food-borne disease and outbreaks, should lead to further refinement in both model development and validation.…”

“…Liebana et al (13) analyzed several methods for molecular typing of five selected serovars of Salmonella and indicated that serotypes of isolates could be deduced based on PFGE patterns. Gaul et al (7) presented an analysis of 674 isolates from 12 Salmonella serotypes that separated into 66 different XbaI PFGE subtypes. The 66 subtypes could be separated into groups of specific serotypes by cluster analysis.…”

Antimicrobial Drug Resistance and Molecular Characterization of Salmonella Isolated from Domestic Animals, Humans and Meat Products

“…Although human salmonellosis has been associated with exposure to other vehicles of transmission (e.g. pets, reptiles, and contaminated water), about 95% of human infections have been found to be associated with ingestion of contaminated foods; namely animal products (Gaul et al 2007;McLaughlin et al 2006;Padungtod and Kaneene 2006), poultry products (Plym and Wierup 2006;Mead et al 1999), sea foods (Duran and Marshall 2005;Ozogul et al 2007;Shabarinath et al 2007) and fresh produce (Johnston et al 2006;Puohiniemi et al 1997). Direct contact with companion and food animals has also been documented as another important route of Salmonella transmission to humans (Coburn et al 2006;Doyle and Erickson 2006;Gorman and Adley 2004;Mead et al 1999;Padungtod and Kaneene 2006).…”