Identification of high-risk Listeria monocytogenes serotypes in lineage I(serotype 1/2a, 1/2c,3a, and 3c) using multiplex PCR

Authors: NHO, SEONGWON - Mississippi State University; ABDELHAMED, HOSSAM - Mississippi State University; REDDY, SWETHA - Mississippi State University; KARSI, ATTILA - Mississippi State University; LAWRENCE, MARK - Mississippi State University

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Listeria monocytogenes is divided into several subgroups (serotypes) based on how they react with serum antibodies. Some of these serotypes have more pathogenic potential than others. In particular, four of the serotypes are associated with almost all outbreaks of listeriosis in people. In this publication, we describe a newly developed DNA-based method to separate serotypes 1/2a and 1/2c, which are associated with human outbreaks, from serotypes 3a and 3c, which are not.

Technical Abstract: Using molecular subtyping techniques, Listeria monocytogenes is divided into three major phylogenetic lineages, and a multiplex PCR method can differentiate five L. monocytogenes subgroups: 1/2a-3a, 1/2c-3c, 1/2b-3b-7, 4b-4d-4e, and 4a-4c. In the current study, we conducted genome comparisons and evaluated serotype-associated genes for their utility as a multiplex PCR-based method for distinguishing high-risk serotypes 1/2a and 1/2c in lineage I from low-risk serotypes 3a and 3c. Methods and Results: Primer sets were developed that are specific for serotype 1/2c (LMOSLCC2372_0308) and serotype 3a (LMLG_0742). These primers were then tested in a multiplex format with primers specific for serotype 1/2a (flaA) to separate serotypes 1/2a, 1/2c, 3a, and 3c using 25 strains of lineage I L. monocytogenes. Conclusions: Here for the first time we report primers specific for L. monocytogenes serotype 1/2c and serotype 3a, and we demonstrate a multiplex PCR method for separating the four serotypes of lineage I L. monocytogenes. Significance and Impact of the Study: The described multiplex PCR assay consistently showed successful separation of 1/2a and 1/2c strains from 3a and 3c strains. PCR is routinely performed in many diagnostic and epidemiologic investigations for L. monocytogenes, and these primers should increase the feasibility and accessibility of L. monocytogenes serotyping. Keywords: Listeria monocytogenes, PCR, serotype, virulence, diagnosis