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

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

Genomic features of resistant <i>Klebsiella pneumonia</i>, isolated from the bloodstream and cerebrospinal fluid of pediatric hospital patients

Introduction. Carbapenemase-producing Klebsiella pneumoniae (CP-Kp), which are international high-risk clones, have become a problem of utmost importance. CP-Kps, adapting to the hospital environment, evolve into convergent pathotypes. Such variants combine traits of two genetic lineages: multidrug resistant (MDR) and hypervirulent. The pathotypes, along with MDR K. pneumoniae, pose an exceptional threat to young patients during systemic infection. The objective of this study is the detailed molecular genetic analysis of MDR isolates of K. pneumoniae detected during the monitoring of resistant Gram-negative bacteria at the National Medical Research Center for Children’s Health in 2014–2021. Materials and methods. Whole-genome sequencing with a subsequent bioinformatics analysis of eight MDR isolates from the bloodstream and cerebrospinal fluid. Results. MDR isolates belonged to 4 sublineages (SL): SL307, SL395, SL29 and SL1198. In the genomes of 6 pangrug-resistant (PDR) isolates, genes associated with resistance to all categories of antibiotics recommended for Enterobacteriaceae therapy were identified. Plasmids were present in all genomes. In 6 isolates, plasmids contained heavy metal ion resistance operons in addition to antibiotic resistance genes. Prophages within the plasmids were also involved in the transfer of resistance genes. The ST395 isolate from the cerebrospinal fluid belonged to the convergent pathotype in terms of resistance and virulence. Comparison of genomes within SLs revealed recombination events in the K- and O-locus regions and the Yersiniabactin operon. Conclusion. Thus, in a sample of resistant K. pneumoniae isolated from bloodstream and cerebrospinal fluid, 6 PDR isolates were detected, one of which belongs to the convergent pathotype ST395

Treatment of children with medulloblastoma without metastatic involvement in the age group older than 3 years: international experience and results of intercenter trial

Background. During the past 20 years, some large international studies have been conducted that evaluated the effectiveness of treatment programs for children with medulloblastoma. At the same time, in the standard risk group, fairly high rates of 5-year overall survival (OS) and event-free survival (EFS) were achieved, which amounted to 85% and 80%, respectively. At the present time some risk-adaptive therapeutic programs are developed according to molecular-biological features of tumor cells and possibility of chemotherapy and craniospinal radiation (CSI) therapy dose reduction. Materials and methods. From 2008 to 2018 fifty one pediatric patients with primary diagnosed medulloblastoma in the age group 318 years were included in trial, 38 in standard risk group, 13 in high risk group (without metastatic disease). Treatment program consisted of surgical removal of the primary tumor site with subsequent chemotherapy (with high-dose cyclophosphamide or thiophosphamide) and radiation therapy (with CSI of 23.4 Gy or 36 Gy, depending on the risk group). In order to detect morphological and molecular biological distinctive features of tumor cells, the following criteria were evaluated: histological variant, molecular subgroup, methyltransferase status by DNMT and MGMT proteins expression, presence of C-MYC/N-MYC gene amplification, Iso17q and TP53 gene mutation. Results. As a result of this study, sufficiently high rates of overall survival and progression/relapse-free survival (PRFS) were achieved in standard and high-risk groups patients, which amounted to 76.08.8% and 83.310.8% with median follow-up 62.96.2 months and 52.27.8 months, respectively. There was revealed patients group in the age 37 years with 100% PRFS and median follow-up 66.98.9 months. At the same time, morphological and molecular biological factors of an unfavorable outcome of the disease were absent in the tumor samples (large cell anaplastic histology, C-MYC/N-MYC gene amplification, Iso17q and TP53 gene mutation). We have also achieved 100% PRFS in patients with desmoplastic tumor histology and in patients, who were treated with thiphosphamide-based chemotherapy regimen. Molecular-biological characteristics analysis of tumor cells showed a negative effect on PRFS of DNMT-positive status (Score 4, by 3 markers) and presence of N-MYC gene amplification (SHH molecular subgroup). Conclusion. There was identified a group of patients aged 3 to 7 years, for whom the possibility for reducing of CSR dose down to 18 Gy opens. Understanding of tumor cells methyltransferase status creates the prerequisites for using of epigenetic demethylating therapy. It is necessary more observations to assess the effect of the chemotherapy regimen with high-dose thiophosphamide on the PRFS

On Burkholderiales order microorganisms and cystic fibrosis in Russia

Abstract Background Microbes infecting cystic fibrosis patients’ respiratory tract are important in determining patients’ functional status. Representatives of Burkholderiales order are the most dangerous. The goal of our investigation was to reveal the diversity of Burkholderiales, define of their proportion in the microbiome of various parts of respiratory tract and determine the pathogenicity of the main representatives. Results In more than 500 cystic fibrosis patients, representing all Federal Regions of Russia, 34.0% were infected by Burkholderia cepacia complex (Bcc), 21.0% by Achromobacter spp. and 12.0% by Lautropia mirabilis. B. cenocepacia was the most numerous species among the Bcc (93.0%), and A. ruhlandii was the most numerous among Achromobacter spp. (58.0%). The most abundant genotype in Bcc was sequence type (ST) 709, and in Achromobacter spp. it was ST36. These STs constitute Russian epidemic strains. Whole genome sequencing of strains A. ruhlandii SCCH3:Ach33–1365 ST36 and B. cenocepacia GIMC4560:Bcn122 ST709 revealed huge resistomes and many virulence factors, which may explain the difficulties in eradicating these strains. An experience of less dangerous B. cenocepcia ST710 elimination was described. Massively parallel sequencing of 16S rDNA amplicons, including V1-V4 hypervariable regions, was used to definite “healthy” microbiome characteristics. Analysis of maxillary sinus lavage of 7 patients revealed infection with Proteobacteria of the same ST as pathogens from sputum, suggesting that the maxillary sinus is a source of infection in cystic fibrosis patients. Conclusions Characterization of the Russian epidemic bacterial strains in the sputum and sinuses of cystic fibrosis patients have better defined the importance of Burkholderiales bacteria. This information may aid in the development of effective approaches for treatment of this disease

Burkholderia contaminans Biofilm Regulating Operon and Its Distribution in Bacterial Genomes

Biofilm formation by Burkholderia spp. is a principal cause of lung chronic infections in cystic fibrosis patients. A “lacking biofilm production” (LBP) strain B. contaminans GIMC4587:Bct370-19 has been obtained by insertion modification of clinical strain with plasposon mutagenesis. It has an interrupted transcriptional response regulator (RR) gene. The focus of our investigation was a two-component signal transduction system determination, including this RR. B. contaminans clinical and LBP strains were analyzed by whole genome sequencing and bioinformatics resources. A four-component operon (BiofilmReg) has a key role in biofilm formation. The relative location (i.e., by being separated by another gene) of RR and histidine kinase genes is unique in BiofilmReg. Orthologs were found in other members of the Burkholderiales order. Phylogenetic analysis of strains containing BiofilmReg operons demonstrated evidence for earlier inheritance of a three-component operon. During further evolution one lineage acquired a fourth gene, whereas others lost the third component of the operon. Mutations in sensor domains have created biodiversity which is advantageous for adaptation to various ecological niches. Different species Burkholderia and Achromobacter strains all demonstrated similar BiofilmReg operon structure. Therefore, there may be an opportunity to develop a common drug which is effective for treating all these causative agents