Mycobacterium tuberculosis Beijing genotype associated with drug resistance is a growing public health problem worldwide. The aim of this study was the assessment of virulence for C57BL/6 mice after infection by clinical M. tuberculosis strains 267/47 and 120/26, which belong to the modern sublineages B0/W148 and Central Asia outbreak of the Beijing genotype, respectively. The sublineages were identified by the analysis of the strains’ whole-genomes. The strains 267/47 and 120/26 were characterized as agents of pre-extensively drug-resistant (pre-XDR) and multidrug-resistant (MDR) tuberculosis, respectively. Both clinical strains were slow-growing in 7H9 broth compared to the M. tuberculosis H37Rv strain. The survival rates of C57BL/6 mice infected by 267/47, 120/26, and H37Rv on the 150th day postinfection were 10%, 40%, and 70%, respectively. Mycobacterial load in the lungs, spleen, and liver was higher and histopathological changes were more expressed for mice infected by the 267/47 strain compared to those infected by the 120/26 and H37Rv strains. The cytokine response in the lungs of C57BL/6 mice after infection with the 267/47, 120/26, and H37Rv strains was different. Notably, proinflammatory cytokine genes Il-1α, Il-6, Il-7, and Il-17, as well as anti-inflammatory genes Il-6 and Il-13, were downregulated after an infection caused by the 267/47 strain compared to those after infection with the H37Rv strain.

Acinetobacter baumannii and Klebsiella pneumoniae are significant nosocomial pathogens worldwide. In this study, the general characterization of A. baumannii and K. pneumoniae isolates obtained from the blood of intensive care unit patients of the multidisciplinary scientific and practical center of emergency medicine from January to September 2024 was performed. Prophage regions and prophage-derived tailspike polysaccharide-depolymerizing or -modifying enzymes within these isolates were identified and characterized in detail using a refined workflow. The protocol, encompassing a comprehensive survey of all predicted bacterial proteins, revealed an average of 6.0 prophage regions per Acinetobacter baumannii genome, including regions putatively derived from filamentous phages, and 4.8 prophage regions per Klebsiella pneumoniae isolate. Analysis of these putative prophage regions indicated that most were related to previously isolated, yet unclassified, temperate phages infecting A. baumannii and K. pneumoniae. However, certain identified sequences likely originated from phages representing novel groups comparatively distant from known phages.

Contamination of laboratory surfaces with nucleic acids and their amplicons is one of the most important problems encountered in nucleic acid amplification methods due to the occurrence of unreliable results. The aim of this study was to select and determine effective regimens for the use of various active agents for decontamination in PCR laboratories. The ability of ethyl alcohol, alkyldimethylbenzylammonium chloride, N,N-bis(3-aminopropyl)dodecylamine, polyhexamethyleneguanidine hydrochloride, hydrogen peroxide, peracetic acid, chlorine dioxide, sodium hypochlorite and neutral anolyte to destroy or irreversibly modify DNA, preventing its subsequent amplification was studied. The decontamination activity was analyzed by simulating the surface contamination with both long (1500 bp) and short (94 bp) amplicons. Hydrogen peroxide 2?%, peracetic acid 0.24?%, dichloroisocyanuric acid 0.01?%, sodium hypochlorite 0.1?% and chlorine dioxide 0.01?% were shown to have decontaminating ability. Notably, dichloroisocyanuric acid decontaminated surfaces from DNA at a concentration 20 times lower than previously described, and sodium hypochlorite at half the concentration, and chlorine dioxide was also found to have decontaminating activity. The absence of decontaminating activity was observed in ethyl alcohol 70?%, alkyldimethylbenzylammonium chloride 2?%, N,N-bis(3-aminopropyl)dodecylamine 2?%, polyhexamethyleneguanidine hydrochloride 2?% and neutral anolyte 0,05?%. The results obtained allow expanding the list of disinfectants recommended for decontamination measures in laboratories using nucleic acid amplification methods in order to prevent contamination of nucleic acids and their amplicons. Keywords: PCR, DNA, amplicons, decontamination, disinfectants.

Klebsiella pneumoniae is one of the most significant nosocomial pathogens and an important cause of human infections worldwide. The microorganism is capable of producing different capsular polysaccharides (CPSs), which are the primary receptors for capsule-specific K. pneumoniae bacteriophages encoding tailspike proteins (TSPs) with polysaccharide-degrading activity. In this study, the novel virulent Przondovirus phage Adeo was isolated and characterized. The phage was able to infect K. pneumoniae strain with a K39 capsular polysaccharide structure. The morphology, biological properties, stability, and genomic organization of Adeo were studied. Comparative genomic and phylogenetic analyses were performed to establish the relationship between the phage and other bacterial viruses. The gene encoding TSP Adeo_gp48 was identified and cloned. Recombinant depolymerase lacking the N-terminal part was expressed, purified, and formed an opaque zone of CPS depolymerization on the K39 K. pneumoniae bacterial lawns. The structural and phylogenetic similarities of Adeo’s TSP to other phage-encoded depolymerases were discussed.

Важной проблемой при работе в ПЦР-лаборатории является возникновение перекрестного загрязнения, которое приводит к появлению ложноположительных результатов. Существует множество способов решения данной проблемы, однако ни один из них не является универсальным. Для деконтаминации сложных поверхностей большой площади предпочтительнее использовать аэрозольный метод обработки. Цель данного исследования заключалась в определении эффективных режимов применения дезинфицирующих средств для деконтаминации от нуклеиновых кислот аэрозольным методом. Анализ деконтаминирующей активности хлорактивных и кислородактивных соединений проводили, моделируя контаминацию поверхностей нуклеиновыми кислотами и бактериями. В процессе работы установлены эффективные режимы проведения аэрозольной деконтаминации. Показаны различия при удалении нуклеиновых кислот и бактериального загрязнения с лабораторных поверхностей.

The occurrence of cross-contamination, which leads to false-positive results when analyzing samples, is an important problem in the PCR laboratory. There are many ways to solve this problem, but none of them is universal. Treatment with aerosol is preferable for decontamination of large areas of complex surfaces. The goal of this study was to determine the efficiency of different modes of aerosol treatment for disinfection and nucleic acids decontamination. The solutions of compounds evolving active chlorine and active oxygen were used for decontamination of surfaces artificially contaminated with exogenous nucleic acids and bacteria. The potency of active ingredients of these solutions was assessed based on results of disinfection and nuclear acids decontamination. We have demonstrated effective modes of aerosol decontamination. The differences in conditions necessary for the nucleic acid decontamination and bacterial disinfection of laboratory surfaces are discussed.