Surveillance of Listeria monocytogenes: Early detection, population dynamics and quasimetagenomic sequencing during selective enrichment

Summary

In this study, we addressed different aspects regarding the implementation
of quasimetagenomic sequencing as a hybrid surveillance method in combination with
enrichment for early detection of Listeria monocytogenes in the food industry. Different
experimental enrichment cultures were used, comprising seven L. monocytogenes strains
of different sequence types (STs), with and without a background microbiota community. To assess whether the proportions of the different STs changed over time during
enrichment, the growth and population dynamics were assessed using dapE colony
sequencing and dapE and 16S rRNA amplicon sequencing. There was a tendency of
some STs to have a higher relative abundance during the late stage of enrichment
when L. monocytogenes was enriched without background microbiota. When coenriched
with background microbiota, the population dynamics of the different STs was more
consistent over time. To evaluate the earliest possible time point during enrichment
that allows the detection of L. monocytogenes and at the same time the generation of
genetic information that enables an estimation regarding the strain diversity in a sample, quasimetagenomic sequencing was performed early during enrichment in the presence of the background microbiota using Oxford Nanopore Technologies Flongle and
Illumina MiSeq sequencing. The application of multiple displacement amplification
(MDA) enabled detection of L. monocytogenes (and the background microbiota) after
only 4 h of enrichment using both applied sequencing approaches. The MiSeq sequencing data additionally enabled the prediction of cooccurring L. monocytogenes strains in
the samples.

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DOI : doi.org/10.1128/AEM.01774-21
NVA : hdl.handle.net/11250/2838263
FULLTEKST : journals.asm.org/doi/10.1128/A...