Dynamics of the Spectrum of Genotypes in Listeria monocytogenes, Which Caused Invasive Listeriosis during the Circulation of SARS-CoV-2 Omicron Variants

Invasive listeriosis (IL) is a disease caused by Listeria monocytogenes due to consumption of contaminated food. Immunosuppression, which is one of the reasons for susceptibility to infection in risk groups, can be increased due to a viral illness. In the early years of the COVID-19 pandemic, changes occurred both in the performance of the sample of patients with IL in the meningitis–septicemia (MS) cohort and in the genomic characteristics of L. monocytogenes that caused the disease. To continue monitoring IL in Moscow region and compare samples of patients with IL and clinical isolates of L. monocytogenes isolated in 2022 with a high incidence of COVID-19 and in 2023–April of 2024 with a decrease in the incidence of this infection. Clinical isolates isolated from Moscow hospital patients diagnosed with IL with manifestations of MS were studied using multilocus and whole-genome sequencing methods, followed by bioinformatic analysis. The parameters of the patient groups were compared based on epicrisis data. Comparison of subgroups of patients with IL showed that the 2022 subgroup had a higher proportion of male patients, patients diagnosed with COVID-19, pneumonia/pulmonary fibrosis, and a higher incidence of deaths. In the subgroup 2023—April 2024 there was a higher proportion of patients with cancer and a higher variety of previous or concomitant viral infections. Clinical isolates of L. monocytogenes were represented by 19 genotypes, five of which belonged to phylogenetic lineage I (PLI). In the period 2023—April 2024, the genetic characteristics of the pathogen of IL in Moscow region continued to change. The diversity of PLII isolates increased, the proportion of PLI isolates decreased, which, as before the pandemic, are represented by L. monocytogenes of two serogroups: 4b and 1/2b. The noted changes in the spectrum of IL pathogen genotypes are not only a consequence of the impact of the COVID-19 pandemic on the health of the population, but also trends in the food industry.