Impact of compounding error on strategies for subtyping pathogenic bacteria

Area of Science:

• Microbiology
• Genetics
• Bioinformatics

Background:

• Comparative-omics generates numerous markers for bacterial intraspecific discrimination.
• High-throughput assays using many markers suffer from compounded errors, reducing classification accuracy.
• Previous methods like bead-arrays showed limitations in robust strain-level classification.

Purpose of the Study:

• To investigate a more robust strategy for bacterial strain discrimination using fewer markers.
• To develop and evaluate variable number of tandem repeat (VNTR) assays for bacterial subtyping.

Main Methods:

• Developed and tested VNTR assays for Vibrio parahaemolyticus and Listeria monocytogenes.
• Evaluated a published VNTR assay for Salmonella enterica.
• Compared VNTR assay performance to pulsed-field gel electrophoresis (PFGE).
• Assessed assay robustness through passage experiments and machine scoring.

Main Results:

• VNTR assays with 4-7 loci provided discriminatory ability comparable to PFGE.
• Machine scoring of VNTR assays yielded robust results.
• Passage experiments revealed minor instability (approx. 5%) in some strains, affecting a single locus/allele.

Conclusions:

• VNTRs offer a robust and portable method for bacterial strain discrimination.
• Utilizing a minimal set of VNTR loci effectively limits error compounding and enhances classification accuracy.
• VNTR-based subtyping presents a reliable alternative to traditional methods for bacterial strain identification.