SEMI-SYNTHETIC PREPARATION AND STRUCTURE CLARIFICATION OF CURVULIDE A

This research was funded by Russian Science Foundation (project № 20-74-00093)

Кандидемия у онкологических больных: фенотипические и молекулярно-генетические характеристики резистентности к противогрибковым лекарственным средствам, гены факторов патогенности Candida spp.

Relevance. The global trend of rapid increase in resistance to antifungal drugs due to multiple factors, dictates the need for continuous monitoring of taxonomic structure and susceptibility of nosocomial pathogens, causing invasive fungal infections, for permanent correction of the optimal prevention and treatment strategies.Purpose: to determine antifungal susceptibility of the main yeast pathogens in candidemia in cancer patients, as well as to determine resistance genes and pathogenic factor genes.Material and Methods. Eighty-two strains of Candida spp. isolated from blood of cancer patients from 2015 to 2021 were analyzed. Minimum inhibitory concentrations of fuconazole, voriconazole, posaconazole, anidulafungin and micafungin were determined by a gradient method (E-test, BioMerieux, France). The EUCAST and CLSI criteria were used for MIC value assessment. The genes, associated with pathogenicity factors, and resistance to antifungal drugs were identifed.Results. Our study results based on EUCAST 2020, v.10.0 criteria showed that triazoles, especially fuconazole, were the least effective drugs in empirical therapy for invasive candidiasis (including candidemia). Resistance of Candida spp. fuconazole was superior to that of voriconazole (47.2 % vs 23.2 %, respectively, p<0.01) and posaconazole (47.2 % vs 30.4 %, respectively, p><0.05). The highest in vitro activity was observed in echinocandins, and anidulafungin was 2 times more active than micafungin (4.1 % of resistant strains vs 11.4 %, respectively), with no statistically signifcant difference (p>0.05). The ERG11 and FKS1 genes associated with resistance to antifungal drugs were detected in 28.6 % of Candida spp. strains. The ERG11 gene was detected in 8.6 % of cases, exclusively in Candida albicans strains. The FKS1 gene was identifed in 20.0 % of strains (85.7 % of them were C. parapsilosis, 7.1 % each were C. tropicalis and C. glabrata). Pathogenic factor genes were identifed in 78.6 % of C. albicans and in 79.1 % of C. parapsilosis strains.Conclusion. Molecular genetic methods for the detection of Candida spp strains carrying resistance genes to antifungal drugs, and the determination of pathogenicity factors are promising trends in searching for biomarkers. They facilitate interpretation of results of microbiological study to assess the ability of Candida spp. strains to develop invasive mycoses.Актуальность. Мировая тенденция стремительного увеличения уровня резистентности к противогрибковым препаратам, которая связана со многими факторами, диктует необходимость постоянного мониторинга таксономической структуры нозокомиальных возбудителей инвазивных грибковых инфекций и их чувствительности к антифунгальным лекарственным средствам с целью постоянной коррекции наиболее оптимальной тактики профилактики и лечения инвазивных грибковых инфекций.Цель исследования – определение чувствительности к антифунгальным препаратам основных возбудителей при кандидемии у онкологических больных, а также определение генов резистентности и факторов патогенности.Материал и методы. Проанализировано 82 штамма Candida spp., выделенных из крови онкологических больных в течение 2015–21 гг. Определение минимальных ингибирующих концентраций флуконазола, вориконазола, позаконазола, анидулафунгина и микафунгина выполняли градиентным методом (Е-тест, BioMerieux, France). Для оценки значений МИК использовали критерии EUCAST и CLSI. Определены гены, ассоциированные с факторами патогенности и резистентности к противогрибковым лекарственным средствам.Результаты. По результатам нашего исследования (критерии EUCAST) в качестве эмпирической терапии инвазивного кандидоза (в т. ч. кандидемии) наименее эффективными препаратами являются триазолы, особенно флуконазол, к которому статистически значимо чаще штаммы Candida spp. резистентны по сравнению с вориконазолом (47,2 % против 23,2 %, p<0,01) и позаконазолом (47,2 % против 30,4 %, p><0,05). Наибольшая активность in vitro отмечается у препаратов группы эхинокандинов, причем анидулафунгин в 2 раза активнее микафунгина (4,1 % резистентных штаммов против 11,4 %), но статистически значимой разницы при этом не выявлено. Гены ERG11 и FKS1, ассоциированные с резистентностью к противогрибковым препаратам, были выявлены у 28,6 % штаммов Candida spp.. Ген ERG11 детектирован в 8,6 % случаев, причем только у штаммов Candida albicans. Ген FKS1 определен у 20,0 % штаммов (85,7 % – C. parapsilosis, по 7,1 % – C. tropicalis и C. glabrata). Гены факторов патогенности определены у 78,6 % штаммов C. albicans и у 79,1 % изолятов C. parapsilosis. Заключение. Молекулярно-генетические методы выявления штаммов Candida spp., несущих гены резистентности к антифунгальным препаратам, определение факторов патогенности –><  0,01) и позаконазолом (47,2 % против 30,4 %, p<0,05). Наибольшая активность in vitro отмечается у препаратов группы эхинокандинов, причем анидулафунгин в 2 раза активнее микафунгина (4,1 % резистентных штаммов против 11,4 %), но статистически значимой разницы при этом не выявлено. Гены ERG11 и FKS1, ассоциированные с резистентностью к противогрибковым препаратам, были выявлены у 28,6 % штаммов Candida spp.. Ген ERG11 детектирован в 8,6 % случаев, причем только у штаммов Candida albicans. Ген FKS1 определен у 20,0 % штаммов (85,7 % – C. parapsilosis, по 7,1 % – C. tropicalis и C. glabrata). Гены факторов патогенности определены у 78,6 % штаммов C. albicans и у 79,1 % изолятов C. parapsilosis. Заключение. Молекулярно-генетические методы выявления штаммов Candida spp., несущих гены резистентности к антифунгальным препаратам, определение факторов патогенности –>< 0,05). Наибольшая активность in vitro отмечается у препаратов группы эхинокандинов, причем анидулафунгин в 2 раза активнее микафунгина (4,1 % резистентных штаммов против 11,4 %), но статистически значимой разницы при этом не выявлено. Гены ERG11 и FKS1, ассоциированные с резистентностью к противогрибковым препаратам, были выявлены у 28,6 % штаммов Candida spp.. Ген ERG11 детектирован в 8,6 % случаев, причем только у штаммов Candida albicans. Ген FKS1 определен у 20,0 % штаммов (85,7 % – C. parapsilosis, по 7,1 % – C. tropicalis и C. glabrata). Гены факторов патогенности определены у 78,6 % штаммов C. albicans и у 79,1 % изолятов C. parapsilosis.Заключение. Молекулярно-генетические методы выявления штаммов Candida spp., несущих гены резистентности к антифунгальным препаратам, определение факторов патогенности – это перспективные направления для поиска биомаркеров, облегчающих сложную задачу трактовки результатов микробиологического исследования по оценке способности штаммов Candida spp. к развитию инвазивных микозов

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

Carbonate-bearing fluorapatite rocks occur at over 30 globally distributed carbonatite complexes and represent a substantial potential supply of phosphorus for the fertiliser industry. However, the process(es) involved in forming carbonate-bearing fluorapatite at some carbonatites remain equivocal, with both hydrothermal and weathering mechanisms inferred. In this contribution, we compare the paragenesis and trace element contents of carbonate-bearing fluorapatite rocks from the Kovdor, Sokli, Bukusu, Catalão I and Glenover carbonatites in order to further understand their origin, as well as to comment upon the concentration of elements that may be deleterious to fertiliser production. The paragenesis of apatite from each deposit is broadly equivalent, comprising residual magmatic grains overgrown by several different stages of carbonate-bearing fluorapatite. The first forms epitactic overgrowths on residual magmatic grains, followed by the formation of massive apatite which, in turn, is cross-cut by late euhedral and colloform apatite generations. Compositionally, the paragenetic sequence corresponds to a substantial decrease in the concentration of rare earth elements (REE), Sr, Na and Th, with an increase in U and Cd. The carbonate-bearing fluorapatite exhibits a negative Ce anomaly, attributed to oxic conditions in a surficial environment and, in combination with the textural and compositional commonality, supports a weathering origin for these rocks. Carbonate-bearing fluorapatite has Th contents which are several orders of magnitude lower than magmatic apatite grains, potentially making such apatite a more environmentally attractive feedstock for the fertiliser industry. Uranium and cadmium contents are higher in carbonate-bearing fluorapatite than magmatic carbonatite apatite, but are much lower than most marine phosphorites

Antibacterial Activity of Benzydamine Hydrochloride against Clinical Isolates of Bacteria, isolated from people in Russia and Spain

Aim to study antibacterial activity of benzydamine hydrochloride, against clinic isolated of bacteria, located in hospitals in Russia and compare this data to results of similar trail of Spanish isolates.Materials  and  method  for this study were used clinical isolates  of bacteria,  which are counted as typical agents  of infections in otorhinolaryngology and gynecology. Enterococcus spp., Escherichia coli, Klebsiella pneumoniae, Staphylococcus spp. and Streptococcus  spp.,  isolated from patients  in Russians  hospitals;  reference  strains  Escherichia coli, Staphylococcus  aureus and Streptococcus agalactiae, from ATCC collection; and also, Lactobacillus acidophilus strain, isolated from probiotic drug «Lactobacterin». Antibacterial activity of benzydamine hydrochloride was evaluated with serial dilution method in agar. For comparison of results we used data of Spanish study of benzydamine activity against clinical isolates and reference strains. The Spanish Study was completed in microbiological department of San-Pau hospital in Barcelona in 2001.Results.  It was indicated that minimum inhibitory concentration (MIC) of benzydamine hydrochloride for clinical isolates of gram-negative and gram-positive  bacteria, isolated from Russian and Spanish hospitals is about the same level: for E. coli it was 640 – 1280  mg/l, for K. pneumoniae  – 512–1280  mg/l, for S. aureus  – 256–1280  mg/l, for S. agalactiae  – 320–1280  mg/l, for S. pyogenes – 256–640 mg/l, for E. faecalis – 512 mg/l, for E. faecium – 256 mg/l, for S. mitis – 640 mg/l, for S. epidermidis 320 – 1280 mg/l, for S. pneumoniae  –  40 mg/l, for S. viridans  –  40 mg/l. The same data was obtained by assessment of sensitivity to benzydamine hydrochloride reference-strains from ATCC collection: for E. coli MIC was 512 – 640 mg/l, for S. aureus – 512 – 640 mg/l, for S. agalactiae – 320 mg/l, for S. pneumoniae – 640 mg/l. Probiotic strain L. acidophilus was resistant to benzydamine hydrochloride activity with MIC = 20000 mg/l. Conclusion: It was indicated that antimicrobial activity of benzydamine hydrochloride against clinical strains, isolated from the patients of hospitals in Russia and Spain. Also, resistance of probiotic strain of lactobacteria was detected to this drug, which indicates the possibility of benzydamine hydrochloride application in clinical practice in otorhinolaryngology  and gynecology without risk of negative influence on normal lactobacterial flora

Capsule-Targeting Depolymerases Derived from <i>Acinetobacter baumannii</i> Prophage Regions

In this study, several different depolymerases encoded in the prophage regions of Acinetobacter baumannii genomes have been bioinformatically predicted and recombinantly produced. The identified depolymerases possessed multi-domain structures and were identical or closely homologous to various proteins encoded in other A. baumannii genomes. This means that prophage-derived depolymerases are widespread, and different bacterial genomes can be the source of proteins with polysaccharide-degrading activities. For two depolymerases, the specificity to capsular polysaccharides (CPSs) of A. baumannii belonging to K1 and K92 capsular types (K types) was determined. The data obtained showed that the prophage-derived depolymerases were glycosidases that cleaved the A. baumannii CPSs by the hydrolytic mechanism to yield monomers and oligomers of the K units. The recombinant proteins with established enzymatic activity significantly reduced the mortality of Galleria mellonella larvae infected with A. baumannii of K1 and K92 capsular types. Therefore, these enzymes can be considered as suitable candidates for the development of new antibacterials against corresponding A. baumannii K types