AUTHOR=Feng Youwei , Yao Hao , Chen Sisi , Sun Xiaowen , Yin Yuelan , Jiao Xin’an 

TITLE=Rapid Detection of Hypervirulent Serovar 4h Listeria monocytogenes by Multiplex PCR

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01309

DOI=10.3389/fmicb.2020.01309

ISSN=1664-302X

ABSTRACT=<p><italic>Listeria monocytogenes</italic> (<italic>L. monocytogenes</italic>) is a ubiquitous foodborne pathogen that comprises 14 serotypes, of which serovar 4h is a novel serotype recently reported. Serovar 4h <italic>L. monocytogenes</italic> belonging to hybrid sub-lineage II exhibit hypervirulent features. Conventional biochemical tests and widely used PCR-based serogrouping schemes could not distinguish serovar 4h strains. In this study, we developed a new multiplex PCR assay for rapid detection of serotype 4h <italic>L. monocytogenes</italic>. Three primer pairs based on the target genes, LMxysn_1095, <italic>lmo1083</italic>, and <italic>smcL</italic>, were designed. The multiplex PCR results showed that serovar 4h strains could be specifically identified from all tested strains, including various <italic>L. monocytogenes</italic> serovars, <italic>Listeria</italic> spp., and other species. The detection limits of the multiplex PCR were 291 fg/μL for genomic DNA and 5.5 × 10<sup>6</sup> CFU/mL for bacterial suspension. Furthermore, pork meat artificially contaminated with serovar 4h <italic>L. monocytogenes</italic> in a concentration of 1.8 × 10<sup>3</sup>–1.8 × 10<sup>0</sup> CFU/10 g were successfully detected within 10–16 h. These results demonstrate that the multiplex PCR with high specificity and sensitivity is applicable for the rapid detection of <italic>L. monocytogenes</italic> serotype 4h strains.</p>