Abstract:
Whole genome sequencing (WGS) has proven to be the ultimate tool for bacterial isolate
characterization and relatedness determination. However, standardized and harmonized workflows,
e.g. for DNA extraction, are required to ensure robust and exchangeable WGS data. Data sharing
between (inter)national laboratories is essential to support foodborne pathogen control, including
outbreak investigation. This study evaluated eight commercial DNA preparation kits for their potential
influence on: (i) DNA quality for Nextera XT library preparation; (ii) MiSeq sequencing (data quality,
read mapping against plasmid and chromosome references); and (iii) WGS data analysis, i.e. isolate
characterization (serotyping, virulence and antimicrobial resistance genotyping) and phylogenetic
relatedness (core genome multilocus sequence typing and single nucleotide polymorphism analysis).
Shiga toxin-producing Escherichia coli (STEC) was selected as a case study. Overall, data quality and
inferred phylogenetic relationships between isolates were not affected by the DNA extraction kit
choice, irrespective of the presence of confounding factors such as EDTA in DNA solution buffers.
Nevertheless, completeness of STEC characterization was, although not substantially, influenced by
the plasmid extraction performance of the kits, especially when using Nextera XT library preparation.
This study contributes to addressing the WGS challenges of standardizing protocols to support data
portability and to enable full exploitation of its potential.
