Publications by authors named "Deyan Donchev"

Article Synopsis
  • Acquired 16S rRNA methyltransferases (16S-RMTases) enable high resistance to aminoglycosides and are linked to resistance against other antibiotics like β-lactams and quinolones.
  • A study conducted on over 10,000 bacterial isolates from 2006 to 2023 found that 1.4% of them carried various methyltransferase genes alongside other significant resistance genes.
  • The research highlighted the diverse origins of these resistance genes in different plasmids and indicated that their ability to acquire more resistance genes poses a significant long-term public health risk.
View Article and Find Full Text PDF
Article Synopsis
  • Water samples for bacterial microbiome studies involve multiple steps, including biomass concentration, DNA extraction, and taxonomic identification, with a focus on evaluating the effectiveness of skimmed milk flocculation (SMF) for bacterial enrichment.
  • In experiments, river water samples treated with SMF showed a significant increase in lactic acid bacteria, but this method ultimately proved unsuitable for microbiome studies due to a too high presence of these organisms that skewed results.
  • The study identified FastSpin Soil, an in-house method, and EurX as the best DNA extraction protocols, revealing that extraction methods have a greater impact on the microbial composition than the databases used for taxonomic identification.
View Article and Find Full Text PDF

During the last few decades, the main focus of numerous studies has been on the human breast milk microbiota and its influence on the infant intestinal microbiota and overall health. The presence of lactic acid bacteria in breast milk affects both the quantitative and qualitative composition of the infant gut microbiota. The aim of this study was to assess the most frequently detected cultivable rod-shaped lactobacilli, specific for breast milk of healthy Bulgarian women and fecal samples of their infants over the first month of life, in 14 mother-infant tandem pairs.

View Article and Find Full Text PDF
Article Synopsis
  • * A study on the Iskar River in Bulgaria analyzed bacterial communities and resistance profiles before and after a large WWTP's discharge, finding significant variations in community compositions over time and location, particularly around specific antibiotic resistance genes.
  • * Although the presence of some ARGs was noted, the overall risk to human health assessed was low, indicating a need for ongoing monitoring of microbial communities and antibiotic resistance in surface waters.
View Article and Find Full Text PDF

This study aims at the identification and characterization of five actinobacterial strains with presumed belonging to the species isolated from tomato and pepper plants, and establishing the potential role of both plants as natural reservoirs of this phytopathogen. Species identification was performed via MALDI-ToF MS, 16S rDNA sequencing and PCR. The strains were Gram-positive with a coryneform cell shape having yellow/orange-pigmented colonies; positive for catalase and esculin, and starch and casein hydrolysis; oxidase-, urease-, indole- and nitrate-reduction-negative and were strictly aerobic.

View Article and Find Full Text PDF
Article Synopsis
  • Carbapenemase-producing Enterobacteriaceae, specifically the ESCPM group, are increasingly recognized as major causes of hospital-acquired infections but lack systematic genomic tracking.
  • A study analyzed 36 clinical isolates from Bulgaria, identifying various carbapenemase genes, with NDM-1 and VIM-4 being the most common.
  • The majority of these resistance genes were found on self-conjugative plasmids, indicating a high potential for gene transfer and reinforcing the need for better infection control protocols.
View Article and Find Full Text PDF

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has brought about significant challenges worldwide. In this study, we present a comprehensive analysis of the genomic epidemiology and lineage dynamics of SARS-CoV-2 in Bulgaria over a three-year period. Through extensive genomic sequencing and data analysis, we investigated the evolution of the virus, the emergence of variants of concern (VOCs), and their impact on the country's pandemic trajectory.

View Article and Find Full Text PDF
Article Synopsis
  • Multidrug-resistant infections are a significant public health issue, emphasizing the need to understand their genetic characteristics.
  • This study discovered the first case of imipenemase (IMP)-carrying strains in Bulgaria, identifying a novel IMP-100 allele and other chromosomal IMP variants.
  • The study finds that these bacterial strains are resistant to last-resort antibiotics but maintain susceptibility to colistin, with various virulence factors indicating a high potential for pathogenicity and biofilm formation.
  • The emergence of IMP-producing strains is concerning, especially as they show resistance to advanced antibiotics like cefiderocol (CFDC).
View Article and Find Full Text PDF

The Two Weeks in the World research project has resulted in a dataset of 3087 clinically relevant bacterial genomes with pertaining metadata, collected from 59 diagnostic units in 35 countries around the world during 2020. A relational database is available with metadata and summary data from selected bioinformatic analysis, such as species prediction and identification of acquired resistance genes.

View Article and Find Full Text PDF

The first recombinant SARS-CoV-2 variants were identified in 2022, causing public health concerns. The importance of recombinant variants has increased especially since the WHO designated the recombinant variant XBB and its lineages as subvariants that require monitoring on 20 November 2022. In this study, we provide the first insights into the new SARS-CoV-2 variant named XAN, a recombinant composed of Omicron sub-lineages BA.

View Article and Find Full Text PDF

The genotyping of the multidrug-resistant species complex is essential to identify outbreaks and to track their source and spread. The aim of this study was to improve and extend the typeability, availability, cost and time efficiency of an existing multi-locus VNTR analysis (MLVA). A modified scheme (MLVA8+) was adopted and validated for strain-level differentiation of the three species involved in human pathology.

View Article and Find Full Text PDF

The ability of certain human pathogens to adapt to plants without losing their virulence toward people is a major concern today. Thus, the aim of the present work was the investigation of the presence of cross-over pathogenic bacteria in infected tomato and pepper plants. The objects of the study were 21 samples from seven different parts of the plants and three from tomato rhizosphere.

View Article and Find Full Text PDF

The evolution of the emerging SARS-CoV-2 variants carrying mutations in the spike protein raises concerns about the possibility of accelerated transmission in the ever-evolving COVID-19 pandemic worldwide. AY.4.

View Article and Find Full Text PDF

Among multiple parameters, applied in the immunologic monitoring of transplantation, the levels of serum soluble CD30 (sCD30) and peripheral regulatory T cells (Tregs) are very promising. These are relatively new biomarkers, considered to reflect immune activation and tolerance in solid organ transplantation. Results are shown here from a preliminary study on the relevance of sCD30 and Tregs in the monitoring of the early post-transplantation period.

View Article and Find Full Text PDF