Search

Emphasized is the need for new approaches and solutions for forming of increased information awareness, knowledge and competencies in the present and future generations to use the possibilities of emerging technologies for technological breakthroughs. The article presents basic machine learning tools of both types: supervised learning, which trains a model on known input and output data and predicts future results, and unsupervised learning, which finds hidden patterns or inherent structures in the input data. Algorithms for the processes of creating an information flow when applying the tools of the Orange system, which can be used for research, analysis and training, are formulated. Experiments related to smart crop production and analyses with different classification, regression and clustering algorithms. The results show that the formulated solutions can be successfully used for different tasks and can be adapted to new technologies and applications. [ABSTRACT FROM AUTHOR]

The increased need to use distance and online forms of training in the modern world forces teachers to seek, develop and use new and diverse teaching models. The pursuit of adequate fair assessment of students’ knowledge and skills, their active participation in the learning process, their independent work on projects and case studies has also posed new challenges for teachers. The article presents models for hierarchical multicomponent assessment of students, aimed at comprehensive assessment of various thinking skills of high and low order, theoretical knowledge and practical skills, etc. A fuzzy evaluation approach is used to formalize the assessor’s subjective logic. [ABSTRACT FROM AUTHOR]

Information security deals with protecting data and information in all of its forms. The information security topic has been an area of growing research and educational interest for years. Many universities started to incorporate security concepts in new or existing courses, following the recommendations of the ISO/IEC 27000 series of standards. Recently, a new CSES2017 curricula in cyber-security education was introduced. The article presents its authors’ experience in delivering education in information security area through courses in several Bulgarian universities. The main topics and educational methods, covered by the courses are presented and some results are discussed. [ABSTRACT FROM AUTHOR]

The article is based on our experience with introducing the concept "ontology" as a form of representing knowledge about the real world, or parts of it, in the courses in Computer Sciences in some Bulgarian universities. Ontologies are introduced as dictionary definitions in the context of knowledge sharing. The simplest case is when they consist of hierarchy of types, specifying classes, and relations among them. In contrast to the general dictionary, the ontology system is characterized by internal unity, logical interrelations, and logical conformity. The notion "ontology" is presented, in the courses of Computer Sciences, as an inseparable component of the Semantic Web. [ABSTRACT FROM AUTHOR]

During a 3-month period from June to the end of August 2016, ~5% mortalities were observed in a farm with rainbow trout ( Oncorhynchus mykiss Walbaum) and one farm of common carp ( Cyprinus carpio L.) in Bulgaria. The disease was manifested by gill ulcers/rot, asphyxiation and bloody ascites. Aeromonas hydrophila was isolated from the internal organs of all the diseased fish. Bacillus mycoides or B. pseudomycoides were recovered from the gill lesions on diseased carp and rainbow trout, respectively, with identification achieved by conventional phenotyping and by sequencing of the 16S rRNA gene. In vivo experiments confirmed that all three organisms were pathogenic to rainbow trout. [ABSTRACT FROM AUTHOR]

Antimicrobial photodynamic therapy (aPDT) has been considered as a promising method to keep under control the multidrug resistance of pathogenic bacteria. As is well-known the PDT procedure involves a photosensitizer and application of proper light spectrum for its activation in the presence of oxygen atmosphere. In general, the produced oxygen species are toxic to the biomolecules which features mainly two mechanisms, which are appropriate to irreversible inactivation of the drug-resistant microbial pathogens. The present study evaluates two pairs of Gram-negative bacteria such as Flavobacterium hydatis (F. hydatis) and Aeromonas hydrophila (A. hydrophila) as multidrug resistant (R) and sensitive (S) strains isolated from natural sources. Two recently synthesized palladium phthalocyanine complexes (PdPcs) with substituents of four methylpyridiloxy groups on peripheral (pPdPc) and non-peripheral (nPdPc) positions were used as photosensitizers. In addition, tetra-methylpyridiloxy substituted Zn(II)-phthalocyanine (ZnPcMe) was tested as a reference photosensitizer taking into accound its high photodynamic inactivation ability towards different pathogenic microorganisms [1]. The results showed full photodynamic inactivation with 5.0 µM nPdPc towards both strains F. hydatis , R and S (6log), but a half of the inactivation value (3log) was obtained with 5.0 µM pPdPc and only for F. hydatis , S. For comparison reason, a well-known zinc phthalocyanine (ZnPcMe) was studied with high efficacy towards both F. hydatis R and S strains. The results on the second pair strains showed complete inactivation with nPdPc (0.4 µM for the both S and R strains) as compared to pPdPc (8 µM for S strain). Comparison between the both new isolates Aeromonas hydrophila (S and R) strains, suggests that PDT efficacy with the applied phthalocyanines is independent on the drug sensitivity of the tested strains [2]. This study suggested the promising base for the development of aPDT as alternative method to keep under control the farm fishes' pathogens. [ABSTRACT FROM AUTHOR]

Copyright of Drug Research / Arzneimittel-Forschung (Editio Cantor Verlag fur Medizin und Naturwissenschaften) is the property of Editio Cantor Verlag fur Medizin und Naturwissenschaften and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lactococcosis caused by Lactococcus garvieae is a bacterial infection affecting fish with a considerable economic impact. Recently, L. garvieae has established itself as an opportunistic pathogen in humans. The aim of the current study was to test classical and molecular-biological methods for the identification of L. garvieae and examine antimicrobial susceptibility and capsule production, an important virulence factor. Additionally, tests for differentiation from closely related species, as well as epidemiological typing, were performed. In a period of 18 years (2002-2019), 24 isolates presumptively identified as L. garvieae were collected from Oncorhynchus mykiss and Salmo salar fish obtained either from retail stores or fish farms. In order to confirm the species, optimized PCR-based protocols were used. As a result, 21 of the tested strains were proved to be L. garvieae ( n = 21). The remaining three isolates were Lactococcus lactis , Streptococcus iniae , and Enterococcus faecalis . Epidemiological typing by randomly amplified polymorphic DNA was performed. Except for a single KG+ isolate, all other strains belonged to the European capsular serotype KG-. All L. garvieae isolates showed susceptibility to all tested antibiotics with the exception of clindamycin, which was a diagnostic sign. A thorough optimization of diagnostic methods is essential to determining the etiology of specific infections affecting the personnel at risk in fish farms, the food industry, or within the broader community.

Escherichia coli ( E. coli ) is a ubiquitous microorganism with pathogenic and saprophytic clones. The objective of this study was to evaluate the presence, virulence, antibiotic resistance and biofilm formation of E. coli in three industrial farms in Bulgaria, as well as their adjacent sites related to the utilization of manure (feces, wastewater in a separator, lagoons, means of transport, and soils). The isolation of single bacterial cultures was performed via standard procedures with modifications, and E. coli isolates were identified via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR). The disk diffusion method was used to assess antimicrobial resistance, and PCR was used to detect genes for antibiotic resistance (GAR) ( qnr , aac (3), amp C, bla SHV/ bla TEM and erm ) and virulence genes ( stx , stx 2all, LT, STa, F4 and eae ). The protocol of Stepanović was utilized to measure the biofilm formation of the isolates. A total of 84 isolates from different samples ( n = 53) were identified as E. coli . Almost all demonstrated antimicrobial resistance, and most of them demonstrated resistance to multiple antibiotics from different classes. No virulence genes coding the Shiga toxin or enterotoxins or those associated with enteropathogenicity were detected. No GAR from those tested for quinolones, aminoglycosides and macrolides were found. However, all isolates that were resistant to a penicillin-class antibiotic (56) had β -lactamase-producing plasmid genes. All of them had amp C, and 34 of them had bla TEM. A total of 14 isolates formed strongly adherent biofilms. These results in a country where the use of antibiotics for growth promotion and prophylaxis in farms is highly restricted corroborate that the global implemented policy on antibiotics in human medicine and in animal husbandry needs revision., Competing Interests: The authors declare no conflicts of interest.

Crassostrea gigas oysters represent a significant global food source with 4.7 million tons harvested per year. In 2001, the bacterium Vibrio aestuarianus subsp. francensis emerged as a pathogen that causes adult oyster mortality in France and Ireland. Its impact on oyster aquaculture has increased in Europe since its re-emergence in 2012. To better understand the evolutionary mechanisms leading to the emergence and persistence over time of this pathogen, we conducted a survey of mollusc diseases through national reference laboratories across Europe. We analysed 54 new genomes of Vibrio aestuarianus (Va) isolated from multiple environmental compartments since 2001, in areas with and without bivalve mortalities. We used a combination of comparative genomics and population genetics approaches and show that Va has a classical epidemic population structure from which the pathogenic Va francensis subspecies emerged and clonally expanded. Furthermore, we identified a specific cus-cop-containing island conferring copper resistance to Va francensis whose acquisition may have favoured the emergence of pathogenic lineages adapted and specialized to oysters., (© 2023 Crown copyright. Molecular Ecology © 2023 John Wiley & Sons Ltd. This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.)

Antimicrobial photodynamic therapy (aPDT) has been considered as a promising methodology to fight the multidrug resistance of pathogenic bacteria. The procedure involves a photoactive compound (photosensitizer), the red or near infrared spectrum for its activation, and an oxygen environment. In general, reactive oxygen species are toxic to biomolecules which feature a mechanism of photodynamic action. The present study evaluates two clinical isolates of Gram-negative Flavobacterium hydatis ( F. hydatis ): a multidrug resistant (R) and a sensitive (S) strain. Both occur in farmed fish, leading to the big production losses because of the inefficacy of antibiotics. Palladium phthalocyanines (PdPcs) with methylpyridiloxy groups linked peripherally (pPdPc) or non-peripherally (nPdPc) were studied with full photodynamic inactivation for 5.0 µM nPdPc toward both F. hydatis , R and S strains (6 log), but with a half of this value (3 log) for 5.0 µM pPdPc and only for F. hydatis , S. In addition to the newly synthesized PdPcs as a "positive control" was applied a well-known highly effective zinc phthalocyanine (ZnPcMe). ZnPcMe showed optimal photocytotoxicity for inactivation of both F. hydatis R and S. The present study is encouraging for a further development of aPDT with phthalocyanines as an alternative method to antibiotic medication to keep under control the harmful pathogens in aquacultures' farms.

The antimicrobial multidrug resistance (AMR) of pathogenic bacteria towards currently used antibiotics has a remarkable impact on the quality and prolongation of human lives. An effective strategy to fight AMR is the method PhotoDynamic Therapy (PDT). PDT is based on a joint action of a photosensitizer, oxygen, and light within a specific spectrum. This results in the generation of singlet oxygen and other reactive oxygen species that can inactivate the pathogenic cells without further regrowth. This study presents the efficacy of a new Pd(II)- versus Zn(II)-phthalocyanine complexes with peripheral positions of methylpyridiloxy substitution groups (pPdPc and ZnPcMe) towards Gram-negative bacteria Aeromonas hydrophila ( A. hydrophila ). Zn(II)-phthalocyanine, ZnPcMe was used as a reference compound for in vitro studies, bacause it is well-known with a high photodynamic inactivation ability for different pathogenic microorganisms. The studied new isolates of A. hydrophila were antibiotic-resistant (R) and sensitive (S) strains. The photoinactivation results showed a full effect with 8 µM pPdPc for S strain and with 5 µM ZnPcMe for both R and S strains. Comparison between both new isolates of A. hydrophila (S and R) suggests that the uptakes and more likely photoinactivation efficacy of the applied phthalocyanines are independent of the drug sensitivity of the studied strains.

Thirty-three Yersinia strains previously characterized by the French Yersinia National Reference Laboratory (YNRL) and isolated from humans and animals were suspected to belong to six novel species by a recently described core genome multilocus sequence typing scheme. These strains and five additional strains from the YNRL were characterized using a polyphasic taxonomic approach including a phylogenetic analysis based on 500 core genes, determination of average nucleotide identity (ANI), determination of DNA G+C content and identification of phenotypic features. Phylogenetic analysis confirmed that the 38 studied strains formed six well-demarcated clades. ANI values between these clades and their closest relatives were <94.7 % and ANI values within each putative novel species were >97.5 %. Distinctive biochemical characteristics were identified in five out of the six novel species. All of these data demonstrated that the 38 strains belong to six novel species of the genus Yersinia : Yersinia artesiana sp. nov., type strain IP42281 T (=CIP 111845 T =DSM 110725 T ); Yersinia proxima sp. nov., type strain IP37424 T (=CIP 111847 T =DSM 110727 T ); Yersinia alsatica sp. nov., type strain IP38850 T (=CIP 111848 T =DSM 110726 T ); Yersinia vastinensis sp. nov., type strain IP38594 T (=CIP 111844 T =DSM 110738 T ); Yersinia thracica sp. nov., type strain IP34646 T (=CIP 111842 T =DSM 110736 T ); and Yersinia occitanica sp. nov., type strain IP35638 T (=CIP 111843 T =DSM 110739 T ).

Captive snakes, that is, a Jamaican boa (Epicrates subflavus) a yellow anaconda (Eunectes notaeus) and a corn snake (Pantherophis guttatus guttatus), died with signs of bacteraemia including the presence of petechial haemorrhages in the mouth and gums and haemorrhages in the lung, spleen and intestines. The abdomen and anus were swollen with bloody-tinged mucus in the colon. Aeromonas hydrophila was recovered in dense virtually pure culture growth from the internal organs. Characterization of the isolates was by phenotyping and sequencing of the 16S rRNA gene (sequence homology of 99% with A. hydrophila) with outputs confirming the identity as A. hydrophila. Pathogenicity experiments confirmed virulence to frogs (Rana esculenta) and rainbow trout (Oncorhynchus mykiss)., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

The role of the enzyme neuraminidase in pathogenicity of the bacillus Erysipelothrix rhusiopathiae was studied. Different substances with low and high molecular weight were tested as inducers of E. rhusiopathiae neuraminidase biosynthesis. It was found that macromolecular complexes induce the secretion of the enzyme. K(M) values for different substrates showed that the affinity of the E. rhusiopathiae neuraminidase increases in parallel with the enlargement of the molecular weight of glycoproteins. Results from the rabbits skin test confirmed the role of E. rhusiopathiae neuraminidase as a factor of pathogenicity with spreading functions.