BackgroundAquaculture is the fastest growing sector of food production worldwide. However, one of the major reasons limiting its effectiveness are infectious diseases among aquatic organisms resulting in vast economic losses. Fighting such infections with chemotherapy is normally used as a rapid and effective treatment. The rise of antibiotic resistance, however, is limiting the efficacy of antibiotics and creates environmental and human safety concerns due to their massive application in the aquatic environment. Bacteriophages are an alternative solution that could be considered in order to protect fish against pathogens while minimizing the side-effects for the environment and humans. Bacteriophages kill bacteria via different mechanisms than antibiotics, and so fit nicely into the ‘novel mode of action’ concept desired for all new antibacterial agents.MethodsThe bacteriophages were isolated from sewage water and characterized by RFLP, spectrum of specificity, transmission electron microscopy (TEM) and sequencing (WGS). Bioinformatics analysis of genomic data enables an in-depth characterization of phages and the choice of phages. This allows an optimised choice of phage for therapy, excluding those with toxin genes, virulence factor genes, and genes responsible for lysogeny.ResultsIn this study, we isolated eleven new bacteriophages: seven infecting Aeromonas and four infecting Pseudomonas, which significantly increases the genomic information of Aeromonas and Pseudomonas phages. Bioinformatics analysis of genomic data, assessing the likelihood of these phages to enter the lysogenic cycle with experimental data on their specificity towards large number of bacterial field isolates representing different locations.ConclusionsFrom 11 newly isolated bacteriophages only 6 (25AhydR2PP, 50AhydR13PP, 60AhydR15PP, 22PfluR64PP, 67PfluR64PP, 71PfluR64PP) have a potential to be used in phage therapy due to confirmed lytic lifestyle and absence of virulence or resistance genes.Electronic supplementary materialThe online version of this article (10.1186/s12985-018-1113-5) contains supplementary material, which is available to authorized users.

Swab, RT-qPCR tests remain the gold standard of diagnostics of SARS-CoV-2 infections. These tests are costly and have limited throughput. We developed a 3-gene, seminested RT-qPCR test with SYBR green-based detection designed to be oversensitive rather than overspecific for high-throughput diagnostics of populations. This two-tier approach depends on decentralized self-collection of saliva samples, pooling, 1st-tier testing with highly sensitive screening test and subsequent 2nd-tier testing of individual samples from positive pools with the IVD test. The screening test was able to detect five copies of the viral genome in 10 µl of isolated RNA with 50% probability and 18.8 copies with 95% probability and reached Ct values that were highly linearly RNA concentration-dependent. In the side-by-side comparison, the screening test attained slightly better results than the commercially available IVD-certified RT-qPCR diagnostic test DiaPlexQ (100% specificity and 89.8% sensitivity vs. 100% and 73.5%, respectively). Testing of 1475 individual clinical samples pooled in 374 pools of four revealed 0.8% false positive pools and no false negative pools. In weekly prophylactic testing of 113 people within 6 months, a two-tier testing approach enabled the detection of 18 infected individuals, including several asymptomatic individuals, with substantially lower cost than individual RT-PCR testing.

Numerous research works have shown that synthesis of pesticides leads to the formation of impurities that may substantially enhance pesticide toxicity. In this study, the effect of manufacturing impurities of pesticide bromfenvinphos (BFVF) such as 1-bromo-2-(2,4-dichlorophenyl)-2-ethoxy ethene (BDCEE) and diethyl [2-(2,4-dichlorophenyl)-2-oxo-ethyl] phosphonate (β-ketophosphonate) on human erythrocytes, being significantly exposed to xenobiotics has been studied. The cells were treated with the compounds studied in the concentrations ranging from 0.1 μM to 250 μM for 4 h. In order to assess the effect of BDCEE and β-ketophosphonate on red blood cells hemolytic changes, changes in cell size (FSC parameter) and oxidation of hemoglobin were studied. Moreover, alterations in reactive oxygen species (ROS) formation, reduced glutathione (GSH) level and acetylcholinesterase (AChE) activity were determined. BDCEE induced an increase in ROS level and caused strong oxidation of hemoglobin as well as a slight change in erythrocytes size and hemolysis, while it did not change GSH level and AChE activity. β-ketophosphonate has not been shown to affect most parameters studied, but it strongly reduced AChE activity. Because changes in the parameters examined were noted at low concentrations of BFVF impurities (5-250 µM), those substances should not negatively affect on red blood cells of humans environmentally exposed to this pesticide.

Swab, quantitative, reverse transcription polymerase chain reaction (RT-qPCR) tests remain the gold standard of diagnostics of SARS-CoV-2 infections. However, these tests are costly and time-consuming, and swabbing limits their throughput. We developed a 3-gene, seminested RT qPCR test with SYBR green-based detection, optimized for testing pooled saliva samples for high-throughput diagnostics of epidemic-affected populations. The proposed two-tier approach depends on decentralized self-collection of saliva samples, pooling, 1st-tier testing with the mentioned highly sensitive screening test and subsequent 2nd-tier testing of individual samples from positive pools with the in vitro diagnostic (IVD) test. The screening test was able to detect 5 copies of the viral genome in 10 μl of isolated RNA with 50% probability and 18.8 copies with 95% probability and reached Ct values that were highly linearly RNA concentration-dependent. In the side-by-side comparison (testing artificial pooled samples), the screening test attained slightly better results than the commercially available IVD-certified RT-qPCR diagnostic test (100% specificity and 89.8% sensitivity vs. 100% and 73.5%, respectively). Testing of 1475 individual clinical samples pooled in 374 pools of 4 revealed 0.8% false positive pools and no false negative pools. In weekly prophylactic testing of 113 people within 6 months, a two-tier testing approach enabled the detection of 18 infected individuals, including several asymptomatic individuals, with a fraction of the costs of individual RT-PCR testing.