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. 2007 Oct;45(10):3323-34.
doi: 10.1128/JCM.00025-07. Epub 2007 Jul 18.

Multiplex, bead-based suspension array for molecular determination of common Salmonella serogroups

Collette Fitzgerald  1 , Marcus Collins, Susan van Duyne, Matthew Mikoleit, Teresa Brown, Patricia Fields
Affiliations

Multiplex, bead-based suspension array for molecular determination of common Salmonella serogroups

Collette Fitzgerald et al. J Clin Microbiol. 2007 Oct.

Abstract

We report the development and evaluation of a Salmonella O-group-specific Bio-Plex assay to detect the six most common serogroups in the United States (B, C(1), C(2), D, E, and O13) plus serotype Paratyphi A. The assay is based on rfb gene targets directly involved in O-antigen biosynthesis; it can be completed 45 min post-PCR amplification. The assay correctly and specifically identified 362 of 384 (94.3%) isolates tested in comparison to traditional serotyping. Seventeen isolates (4.4%) produced results consistent with what is known about the molecular basis for serotypes but different from the results of traditional serotyping, and five isolates (1.3%) generated false-negative results. Molecular determination of the serogroup for rough isolates was consistent with a common serotype in most instances, indicating that this approach has the potential to provide O-group information for isolates that do not express an O antigen. We also report the sequence of the O-antigen-encoding rfb gene cluster from Salmonella enterica serotype Poona (serogroup O13). Compared with other, previously characterized rfb regions, the O13 rfb gene cluster was most closely related to Escherichia coli O127 and O86. The O-group Bio-Plex assay described here provides an easy-to-use, high-throughput system for rapid detection of common Salmonella serogroups.

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Figures

FIG. 1.
FIG. 1.
Comparison of organization and G+C contents of rfb gene clusters from Salmonella O13 (a) (this study) and E. coli O127 (b) (17). The percentage of G+C was calculated and plotted for each 100 bases. Putative ORFs are represented by open arrows in which the assigned gene names are given. *, Salmonella O13 glycosyltransferases had 3.2% to 11.7% amino acid identity to E. coli O127 orf9.
FIG. 2.
FIG. 2.
Examples of raw MFIs (A) and positive/negative (P/N) ratios (B) for each O-group-specific bead set averaged for five positive samples each. (C) P/N ratios for each O-group-specific bead set for a Salmonella serovar Dublin isolate.
FIG. 2.
FIG. 2.
Examples of raw MFIs (A) and positive/negative (P/N) ratios (B) for each O-group-specific bead set averaged for five positive samples each. (C) P/N ratios for each O-group-specific bead set for a Salmonella serovar Dublin isolate.
FIG. 3.
FIG. 3.
PFGE cluster analysis of Salmonella serogroup A and D isolates.
See this image and copyright information in PMC

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