Background The dual infection with SARS-CoV-2 is poorly described and is currently under discussion. We present a study of two strains of SARS-CoV-2 detected in the same patient during the same disease presentation. Case presentation A patient in their 90 s was hospitalised with fever. Oropharyngeal swab obtained on the next day (sample 1) tested positive for SARS-CoV-2. Five days later, the patient was transferred to the ICU (intensive care unit) of the hospital specialising in the treatment of COVID-19 patients, where the patient's condition progressively worsened and continuous oxygen insufflation was required. Repeated oropharyngeal swab (sample 2), which was taken eight days after the first one, also tested positive for SARS-CoV-2. After 5 days of ICU treatment, the patient died. The cause of death was a coronavirus infection, which progressed unfavourably due to premorbid status. We have performed sequencing of full SARS-CoV-2 genomes from oropharyngeal swabs obtained eight days apart. Genomic analysis revealed the presence of two genetically distant SARS-CoV-2 strains in both swabs. Detected strains belong to different phylogenetic clades (GH and GR) and differ in seven nucleotide positions. The relative abundance of strains was 70% (GH) and 30% (GR) in the first swab, and 3% (GH) and 97% (GR) in the second swab. Conclusions Our findings suggest that the patient was infected by two genetically distinct SARS-CoV-2 strains at the same time. One of the possible explanations is that the second infection was hospital-acquired. Change of the dominant strain ratio during disease manifestation could be explained by the advantage or higher virulence of the GR clade strain.

Non-typhoidal Salmonella infections remain a significant public health problem worldwide. In this study, we present the first detailed genomic analysis report based on short-read (Illumina) whole-genome sequencing (WGS) of 45 multidrug-resistant (MDR) Salmonella enterica subsp. enterica serotype Infantis isolates from poultry and meat product samples obtained in Russia during 2018–2020, and long-read (MinION) WGS of five more representative isolates. We sought to determine whether foodborne S. Infantis have acquired new characteristics, traits, and dynamics in MDR growth in recent years. All sequenced isolates belonged to the sequence type ST32 and more than the half of isolates was characterized by six similar antimicrobial susceptibility profiles, most of which corresponded well with the antimicrobial resistance determinants to aminoglycosides, sulphonamides, tetracycline, and chloramphenicol revealed in silico. Some of the isolates were characterized by the presence of several types of plasmids simultaneously. Plasmid typing using WGS revealed Col440I, ColpVC, ColRNAI, IncFIB, IncFII, IncX1, IncHI2, IncHI2A, and IncN replicons. The identified virulence genes for 45 whole genomes of S. Infantis were similar and included 129 genes encoding structural components of the cell, factors responsible for successful invasion of the host, and secreted products. These data will be a valuable contribution to further comparative genomics of S. Infantis circulating in Russia, as well as to epidemiological surveillance of foodborne Salmonella isolates and investigations of Salmonella outbreaks.

This study provides a thorough investigation of a diverse set of antimicrobial resistant (AMR) Staphylococcus aureus isolates collected from a broad range of ready-to-eat (RTE) food in various geographic regions of Russia ranging from Pskov to Kamchatka. Thirty-five isolates were characterized using the whole genome sequencing (WGS) analysis in terms of clonal structure, the presence of resistance and virulence determinants, as well as plasmid replicon sequences and CRISPR/Cas systems. To the best of our knowledge, this is the first WGS-based surveillance of Russian RTE food-associated S. aureus isolates. The isolates belonged to fifteen different multilocus sequence typing (MLST)-based types with a predominant being the ones of clonal complex (CC) 22. The isolates studied can pose a threat to public health since about 40% of the isolates carried at least one enterotoxin gene, and 70% of methicillin-resistant (MRSA) isolates carried a tsst1 gene encoding a toxin that may cause severe acute disease. In addition, plasmid analysis revealed some important characteristics, e.g., Rep5 and Rep20 plasmid replicons were a “signature” of MRSA CC22. By analyzing the isolates belonging to the same/single strain based on cgMLST analysis, we were able to identify the differences in their accessory genomes marking their dynamics and plasticity. This data is very important since S. aureus isolates studied and RTE food, in general, represent an important route of transmission and dissemination of multiple pathogenic determinants. We believe that the results obtained will facilitate performing epidemiological surveillance and developing protection measures against this important pathogen in community settings.

Objective. To analyze frequency and identify genetic determinants of resistance of non-typhoid Salmonella (NTS) producing extended-spectrum β-lactamase (ESBL) isolated in the Russian Federation over the period 2016 to 2020. Materials and Methods. Salmonella isolates, suspected to ESBL production, were collected by the All-Russia Reference Center of Salmonellosis during the national Salmonellosis surveillance program. Phenotypic resistance was determined by the broth microdilution method using G-I and G-II Mikrolatest®SensiLaTest MIC plates and by the double-disk synergy test. Whole genome sequencing was performed on the NextSeq platform (Illumina, USA), with subsequent de novo genome assembly (SPAdes 3.15.4), identification of plasmid types (MOB-suite v3.0.0), and identification of resistance genes (AMRFinderPlus v3.10.40). Results. Out of 1792 NTS isolates, 22 strains contained bla-genes of molecular classes A and D (blaTEM, blaCTX-M, blaSHV, blaOXA), one strain – AmpC (blaCMY-2) and three strains – combination ESBL of class A and AmpC (blaTEM, blaCMY-2, blaDHA). The frequency of occurrence of ESBL-producing Salmonella is 1.3%, AmpC – 0.2%. Additionally, strains were resistant to other non-β-lactam antibiotics. Six different types of plasmids were identified (IncI, IncFIB, IncC, IncHI2A, IncL/M and IncX1) in studied isolates. It was possible for 17 strains to identify location of resistance genes in plasmids of a certain type. Conclusions. The frequency of occurrence of Salmonella strains producing ESBL and AmpC was 1.45%, which were found in sporadic cases of human diseases, as well as food and environmental objects were sources of isolation. The fact of detection of such strains among various NTC serotypes and a wide range of sources of isolation confirms the relevance of monitoring antimicrobial resistance of Salmonella strains in the future.