To improve our understanding of the genetic links between strains originating from food and strains responsible for human diseases, we studied the genetic diversity and population structure of 130 epidemiologically unrelated Listeria monocytogenes strains. Strains were isolated from different sources and ecosystems in which the bacterium is commonly found. We used rRNA gene restriction fragment length polymorphism analysis with two endonucleases and random multiprimer DNA analysis with seven oligonucleotide primers to study multiple genetic features of each strain. We used three clustering methods to identify genetic links between individual strains and to determine the precise genetic structure of the population. The combined results confirmed that L. monocytogenes strains can be divided into two major phylogenetic divisions. The method used allowed us to demonstrate that the genetic structure and diversity of the two phylogenetic divisions differ. Division I is the most homogeneous and can easily be divided into subgroups with dissimilarity distances of less than 0.30. Each of these subgroups mainly, or exclusively, contains a single serotype (1/2b, 4b, 3b, or 4a). The serotype 4a lineage appears to form a branch that is highly divergent from the phylogenetic group containing serotypes 1/2b, 4b, and 3b. Division II contains strains of serotypes 1/2a, 1/2c, and 3a. It exhibits more genetic diversity with no peculiar clustering. The fact that division II is more heterogeneous than division I suggests that division II evolved from a common ancestor earlier than division I. A significant association was found between division I and human strains, suggesting that strains from division I are better adapted to human hosts. Listeria monocytogenes was first described by Murray in 1926 in guinea pigs and was recognized as a human pathogen over 70 years ago. Its clinical manifestations include meningitis, meningoencephalitis, bacteremia (27), and occasionally localized infections (16). Listeriosis is particularly dangerous for immunocompromised people and pregnant women, as fetuses may be affected by perinatal listeriosis (23). It is now known that humans become infected after ingesting contaminated food products (10). The expansion of the agro-food industry, together with the use of cold storage systems, has led to the contamination of a wide variety of foods with listeriae (10), resulting in large food-borne outbreaks. However, sporadic listeriosis remains the most frequent manifestation of the illness (2).Although we have a thorough understanding of the virulence of the bacterium and the physiopathology of the illness, the epidemiology of human listeriosis is not fully understood (26). All 13 L. monocytogenes serotypes can cause human listeriosis, but serotypes 1/2a, 1/2b, and 4b account for 95% of the cases that occur (22). The differential prevalence of these serotypes and the absence of clear links between particular forms of listeriosis and certain serotypes may be explained by studying the genetic structure of th...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.