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

Area of Science:

• Microbiology
• Molecular Biology
• Immunology

Background:

• Traditional Salmonella serotyping is time-consuming and labor-intensive.
• Accurate and rapid identification of Salmonella serogroups is crucial for public health surveillance and outbreak investigations.
• Molecular methods offer potential for faster and more specific serogroup determination.

Purpose of the Study:

• To develop and evaluate a Salmonella O-group-specific Bio-Plex assay.
• To detect six common US Salmonella serogroups (B, C1, C2, D, E, O13) and serotype Paratyphi A.
• To assess the assay's performance against traditional serotyping methods.

Main Methods:

• Development of a Bio-Plex assay targeting rfb genes involved in O-antigen biosynthesis.
• Testing the assay on 384 Salmonella isolates.
• Comparison of results with traditional serotyping.
• Sequencing of the O-antigen-encoding rfb gene cluster from Salmonella enterica serotype Poona (O13).

Main Results:

• The Salmonella O-group Bio-Plex assay correctly identified 94.3% of isolates compared to traditional serotyping.
• Discrepant results (4.4%) were consistent with known molecular serotype bases.
• Five isolates (1.3%) yielded false-negative results.
• Molecular determination provided O-group information for rough isolates.
• The O13 rfb gene cluster showed closest relation to Escherichia coli O127 and O86.

Conclusions:

• The Salmonella O-group Bio-Plex assay is a rapid, high-throughput, and accurate method for detecting common Salmonella serogroups.
• This molecular approach has potential for identifying O-group information in isolates lacking O antigen expression.
• The assay facilitates efficient Salmonella surveillance and diagnostics.