Outcomes of the multicenter monitoring of the causative agent of invasive listeriosis in the metropolis

Abstract

Introduction. Invasive listeriosis is a rare disease posing a threat to high-risk groups and often leading to a fatal outcome. Its causative agent is Listeria monocytogenes, a ubiquitous saprophyte that has turned into an important foodborne pathogen with the growing industry of semi-cooked and ready-to-eat products. The aim of the study is the characterization of L. monocytogenes isolates in the Moscow region and identification of possible causes of susceptibility to infection Materials and methods. The multicenter monitoring of L. monocytogenes was conducted in the Moscow metropolitan area, using bacteriological and genomic methods for description of the pathogen, medical history collection and detailed analysis of patient case summaries. Results. In the cohorts of patients with perinatal listeriosis (PL) and meningitis-septicemia (MS), invasive listeriosis had a year-round occurrence with slight upswings in MarchApril and JulyNovember. During the COVID-19 pandemic, in the MS group, the minimum age of patients decreased to 31 years and the proportion of deaths increased 1.57-fold compared to 20182019. During the pandemic, an increase in the diversity of L. monocytogenes genotypes was observed, along with changes in the spectrum of pathogen genotypes throughout the pandemic stages. During the monitoring, a total of 73 L. monocytogenes clinical isolates belonging to 24 genotypes were described. Seven genotypes belonged to the first phylogenetic lineage (PLI); 14 genotypes belonged to PLII. The PL cohort had the highest proportion of PLI genotypes (52%). In the MS cohort, the group of men had the widest diversity of genotypes, 6 of which were identical to genotypes of food isolates. In the analysed set of isolates, 12 new profiles of internalin genes were identified and described. The whole genome sequencing detected the presence of plasmids in 9 of 58 genomes of clinical isolates. The comparison of core genomes revealed an epidemic relationship between isolates of the same genotype for ST4, ST21, and ST425. Conclusion. The performed study presents a detailed description of the diversity and virulence of L. monocytogenes circulating in the Moscow metropolitan area, thus providing information for timely diagnosis and treatment of invasive listeriosis.