Ability Of Pathogen Research Articles

The gastrointestinal antibiotic resistome in pediatric leukemia and lymphoma patients.

Most children with leukemia and lymphoma experience febrile neutropenia. These are treated with empiric antibiotics that include β-lactams and/or vancomycin. These are often administered for extended periods, and the effect on the resistome is unknown. We examined the impact of repeated courses and duration of antibiotic use on the resistome of 39 pediatric leukemia and lymphoma patients. Shotgun metagenome sequences from 127 stool samples of pediatric oncology patients were examined for abundance of antibiotic resistance genes (ARGs) in each sample. Abundances were grouped by repeated courses (no antibiotics, 1-2 courses, 3+ courses) and duration (no use, short duration, long and/or mixed durationg) of β-lactams, vancomycin and "any antibiotic" use. We assessed changes in both taxonomic composition and prevalence of ARGs among these groups. We found that Bacteroidetes taxa and β-lactam resistance genes decreased, while opportunistic Firmicutes and Proteobacteria taxa, along with multidrug resistance genes, increased with repeated courses and/or duration of antibiotics. Efflux pump related genes predominated (92%) among the increased multidrug genes. While we found β-lactam ARGs present in the resistome, the taxa that appear to contain them were kept in check by antibiotic treatment. Multidrug ARGs, mostly efflux pumps or regulators of efflux pump genes, were associated with opportunistic pathogens, and both increased in the resistome with repeated antibiotic use and/or increased duration. Given the strong association between opportunistic pathogens and multidrug-related efflux pumps, we suggest that drug efflux capacity might allow the opportunistic pathogens to persist or increase despite repeated courses and/or duration of antibiotics. While drug efflux is the most direct explanation, other mechanisms that enhance the ability of opportunistic pathogens to handle environmental stress, or other aspects of the treatment environment, could also contribute to their ability to flourish within the gut during treatment. Persistence of opportunistic pathogens in an already dysbiotic and weakened gastrointestinal tract could increase the likelihood of life-threatening blood borne infections. Of the 39 patients, 59% experienced at least one gastrointestinal or blood infection and 60% of bacteremia's were bacteria found in stool samples. Antimicrobial stewardship and appropriate use and duration of antibiotics could help reduce morbidity and mortality in this vulnerable population.

Stimulation of Surface Polysaccharide Production under Aerobic Conditions Confers Aerotolerance in Campylobacter jejuni.

The ability of a foodborne pathogen to tolerate environmental stress critically affects food safety by increasing the risk of pathogen survival and transmission in the food supply chain. Campylobacter jejuni, a leading bacterial cause of foodborne illnesses, is an obligate microaerophile and is sensitive to atmospheric levels of oxygen. Currently, the molecular mechanisms of how C. jejuni withstands oxygen toxicity under aerobic conditions have not yet been fully elucidated. Here, we show that when exposed to aerobic conditions, C. jejuni develops a thick layer of bacterial capsules, which in turn protect C. jejuni under aerobic conditions. The presence of both capsular polysaccharides and lipooligosaccharides is required to protect C. jejuni from excess oxygen in oxygen-rich environments by alleviating oxidative stress. Under aerobic conditions, C. jejuni undergoes substantial transcriptomic changes, particularly in the genes of carbon metabolisms involved in amino acid uptake, the tricarboxylic acid (TCA) cycle, and the Embden-Meyerhof-Parnas (EMP) pathway despite the inability of C. jejuni to grow aerobically. Moreover, the stimulation of carbon metabolism by aerobiosis increases the level of glucose-6-phosphate, the EMP pathway intermediate required for the synthesis of surface polysaccharides. The disruption of the TCA cycle eliminates aerobiosis-mediated stimulation of surface polysaccharide production and markedly compromises aerotolerance in C. jejuni. These results in this study provide novel insights into how an oxygen-sensitive microaerophilic pathogen survives in oxygen-rich environments by adapting its metabolism and physiology. IMPORTANCE Oxygen-sensitive foodborne pathogens must withstand oxygen toxicity in aerobic environments during transmission to humans. C. jejuni is a major cause of gastroenteritis, accounting for 400 million to 500 million infection cases worldwide per year. As an obligate microaerophile, C. jejuni is sensitive to air-level oxygen. However, it has not been fully explained how this oxygen-sensitive zoonotic pathogen survives in aerobic environments and is transmitted to humans. Here, we show that under aerobic conditions, C. jejuni boosts its carbon metabolism to produce a thick layer of bacterial capsules, which in turn act as a protective barrier conferring aerotolerance. The new findings in this study improve our understanding of how oxygen-sensitive C. jejuni can survive in aerobic environments.

3D-printed dual drug delivery nanoparticle- loaded hydrogels to combat antibiotic-resistant bacteria.

Implant-associated infections are not easy to diagnose and very difficult to treat, due to the ability of major pathogens, such as Staphylococcus aureus, to develop biofilms and escape the immune response and antibiotic treatment. We, therefore, aimed to develop a 3D-printed dual rifampicin (Rif)- and vancomycin (Van)-loaded polylactic- co-glycolic acid (PLGA) nanoparticles (NPs) delivery system based on hydrogels made of gelatin methacrylate (GelMA). The release of Rif and Van from NPs manufactured from different PLGA molecular weights was studied in phosphate-buffered saline for 21 days. Low molecular weight PLGA NPs exhibited the fastest release of Rif and Van within the first 7 days and were selected for antimicrobial evaluation. Four different GelMA-based 3D-printed samples were successfully produced, carrying non-loaded NPs, Rif-NPs, Van-NPs, or alternating layers of Rif-NPs and Van-NP. The exposition of S. aureus against increased concentrations of Rif or Van produced new resistant strains to Rif (RifR) or Van (VanR). The GelMA hydrogel co-delivering Rif and Van eradicated S. aureus RN4220 RifR and RN4220 VanR strains. S. aureus RN4220 and S. aureus AMC 201 colonies developed resistance to Rif after contact with the GelMA hydrogel containing only Rif-NPs which appeared to be due to known mutations in the rpoB gene. In conclusion, 3D-printed GelMA hydrogel loaded with PLGA Rif-Van-NPs drug delivery system show promising in vitro results to prevent implant-associated infections caused by antimicrobial-resistant bacteria.

Exploring Possible Ways to Enhance the Potential and Use of Natural Products through Nanotechnology in the Battle against Biofilms of Foodborne Bacterial Pathogens

Biofilms enable pathogenic bacteria to survive in unfavorable environments. As biofilm-forming pathogens can cause rapid food spoilage and recurrent infections in humans, especially their presence in the food industry is problematic. Using chemical disinfectants in the food industry to prevent biofilm formation raises serious health concerns. Further, the ability of biofilm-forming bacterial pathogens to tolerate disinfection procedures questions the traditional treatment methods. Thus, there is a dire need for alternative treatment options targeting bacterial pathogens, especially biofilms. As clean-label products without carcinogenic and hazardous potential, natural compounds with growth and biofilm-inhibiting and biofilm-eradicating potentials have gained popularity as natural preservatives in the food industry. However, the use of these natural preservatives in the food industry is restricted by their poor availability, stability during food processing and storage. Also there is a lack of standardization, and unattractive organoleptic qualities. Nanotechnology is one way to get around these limitations and as well as the use of underutilized bioactives. The use of nanotechnology has several advantages including traversing the biofilm matrix, targeted drug delivery, controlled release, and enhanced bioavailability, bioactivity, and stability. The nanoparticles used in fabricating or encapsulating natural products are considered as an appealing antibiofilm strategy since the nanoparticles enhance the activity of the natural products against biofilms of foodborne bacterial pathogens. Hence, this literature review is intended to provide a comprehensive analysis of the current methods in nanotechnology used for natural products delivery (biofabrication, encapsulation, and nanoemulsion) and also discuss the different promising strategies employed in the recent and past to enhance the inhibition and eradication of foodborne bacterial biofilms.

Bordetella bronchiseptica-Mediated Interference Prevents Influenza A Virus Replication in the Murine Nasal Cavity.

Colonization resistance, also known as pathogen interference, describes the ability of a colonizing microbe to interfere with the ability of an incoming microbe to establish infection, and in the case of pathogenic organisms, cause disease in a susceptible host. Furthermore, colonization-associated dysbiosis of the commensal microbiota can alter host immunocompetence and infection outcomes. Here, we investigated the role of Bordetella bronchiseptica nasal colonization and associated disruption of the nasal microbiota on the ability of influenza A virus to establish infection in the murine upper respiratory tract. Targeted sequencing of the microbial 16S rRNA gene revealed that B. bronchiseptica colonization of the nasal cavity efficiently displaced the resident commensal microbiota-the peak of this effect occurring 7 days postcolonization-and was associated with reduced influenza associated-morbidity and enhanced recovery from influenza-associated clinical disease. Anti-influenza A virus hemagglutinin-specific humoral immune responses were not affected by B. bronchiseptica colonization, although the cellular influenza PA-specific CD8+ immune responses were dampened. Notably, influenza A virus replication in the nasal cavity was negated in B. bronchiseptica-colonized mice. Collectively, this work demonstrates that B. bronchiseptica-mediated pathogen interference prevents influenza A virus replication in the murine nasal cavity. This may have direct implications for controlling influenza A virus replication in, and transmission events originating from, the upper respiratory tract. IMPORTANCE The interplay of microbial species in the upper respiratory tract is important for the ability of an incoming pathogen to establish and, in the case of pathogenic organisms, cause disease in a host. Here, we demonstrate that B. bronchiseptica efficiently colonizes and concurrently displaces the commensal nasal cavity microbiota, negating the ability of influenza A virus to establish infection. Furthermore, B. bronchiseptica colonization also reduced influenza-associated morbidity and enhanced recovery from influenza-associated disease. Collectively, this study indicates that B. bronchiseptica-mediated interference prevents influenza A virus replication in the upper respiratory tract. This result demonstrates the potential for respiratory pathogen-mediated interference to control replication and transmission dynamics of a clinically important respiratory pathogen like influenza A virus.

Animal movement and associated infectious disease risk in a metapopulation.

Animal movements among habitat patches or populations are important for maintaining long-term genetic and demographic viability, but connectivity may also facilitate disease spread and persistence. Understanding factors that influence animal movements is critical to understanding potential transmission risk and persistence of communicable disease in spatially structured systems. We evaluated effects of sex, age and Mycoplasma ovipneumoniae infection status at capture on intermountain movements and seasonal movement rates observed in desert bighorn sheep (Ovis canadensis nelsoni) using global positioning system collar data from 135 individuals (27 males, 108 females) in 14 populations between 2013 and 2018, following a pneumonia outbreak linked to the pathogen M. ovipneumoniae in the Mojave Desert, California, USA. Based on logistic regression analysis, intermountain movements were influenced by sex, age and most notably, infection status at capture: males, older animals and uninfected individuals were most likely to make such movements. Based on multiple linear regression analysis, females that tested positive for M. ovipneumoniae at capture also had lower mean daily movement rates that were further influenced by season. Our study provides empirical evidence of a pathogenic infection decreasing an individual's future mobility, presumably limiting that pathogen's ability to spread, and ultimately influencing transmission risk within a spatially structured system.

Mutation of Phenylalanine 23 of Newcastle Disease Virus Matrix Protein Inhibits Virus Release by Disrupting the Interaction between the FPIV L-Domain and Charged Multivesicular Body Protein 4B.

The matrix (M) protein FPIV L-domain is conserved among multiple paramyxoviruses; however, its function and the associated mechanism remain unclear. In this study, the paramyxovirus Newcastle disease virus (NDV) was employed to study the FPIV L-domain. Two recombinant NDV strains, each carrying a single amino acid mutation at the Phe (F23) or Pro (P24) site of 23FPIV/I26 L-domain, were rescued. Growth defects were observed in only the recombinant SG10-F23A (rSG10-F23A) strain. Subsequent studies focused on rSG10-F23A revealed that the virulence, pathogenicity, and replication ability of this strain were all weaker than those of wild-type strain rSG10 and that a budding deficiency contributed to those weaknesses. To uncover the molecular mechanism underlying the rSG10-F23A budding deficiency, the bridging proteins between the FPIV L-domain and endosomal sorting complex required for transported (ESCRT) machinery were explored. Among 17 candidate proteins, only the charged multivesicular body protein 4 (CHMP4) paralogues were found to interact more strongly with the NDV wild-type M protein (M-WT) than with the mutated M protein (M-F23A). Overexpression of M-WT, but not of M-F23A, changed the CHMP4 subcellular location to the NDV budding site. Furthermore, a knockdown of CHMP4B, the most abundant CHMP4 protein, inhibited the release of rSG10 but not that of rSG10-F23A. From these findings, we can reasonably infer that the F23A mutation of the FPIV L-domain blocks the interaction between the NDV M protein and CHMP4B and that this contributes to the budding deficiency and consequent growth defects of rSG10-F23A. This work lays the foundation for further study of the FPIV L-domain in NDV and other paramyxoviruses. IMPORTANCE Multiple viruses utilize a conserved motif, termed the L-domain, to act as a cellular adaptor for recruiting host ESCRT machinery to their budding site. Despite the FPIV type L-domain having been identified in some paramyxoviruses 2 decades ago, its function in virus life cycles and its method of recruiting the ESCRT machinery are poorly understood. In this study, a single amino acid mutation at the F23 site of the 23FPIV26 L-domain was found to block NDV budding at the late stage. Furthermore, CHMP4B, a core component of the ESCRT-III complex, was identified as a main factor that links the FPIV L-domain and ESCRT machinery together. These results extend previous understanding of the FPIV L-domain and, therefore, not only provide a new approach for attenuating NDV and other paramyxoviruses but also lay the foundation for further study of the FPIV L-domain.

A hierarchy of cell death pathways confers layered resistance to shigellosis in mice.

Bacteria of the genus Shigella cause shigellosis, a severe gastrointestinal disease driven by bacterial colonization of colonic intestinal epithelial cells. Vertebrates have evolved programmed cell death pathways that sense invasive enteric pathogens and eliminate their intracellular niche. Previously we reported that genetic removal of one such pathway, the NAIP-NLRC4 inflammasome, is sufficient to convert mice from resistant to susceptible to oral Shigella flexneri challenge (Mitchell et al., 2020). Here, we investigate the protective role of additional cell death pathways during oral mouse Shigella infection. We find that the Caspase-11 inflammasome, which senses Shigella LPS, restricts Shigella colonization of the intestinal epithelium in the absence of NAIP-NLRC4. However, this protection is limited when Shigella expresses OspC3, an effector that antagonizes Caspase-11 activity. TNFα, a cytokine that activates Caspase-8-dependent apoptosis, also provides potent protection from Shigella colonization of the intestinal epithelium when mice lack both NAIP-NLRC4 and Caspase-11. The combined genetic removal of Caspases-1, -11, and -8 renders mice hyper-susceptible to oral Shigella infection. Our findings uncover a layered hierarchy of cell death pathways that limit the ability of an invasive gastrointestinal pathogen to cause disease.

Erosion of Quantitative Resistance in Wheat and Barley to fusarium Head Blight: Gene Pyramiding Achieves and Durability Study

Background: Fusarium head blight (FHB), caused by several fusarium species, is one of the diseases causing the greatest worldwide damage to small grain cereals, especially wheat and barley. FHB outbreaks can substantially diminish grain yield and end-use quality due to sterile florets and withered mycotoxin-contaminated grain kernels. Great effort has been accomplished to combat FHB in the past decades; however, solutions to prevent FHB damage are limited. The development of quantitative resistant cultivars is considered a sustainable and highly desired approach to reducing FHB damage. Objective: This review aims to combine novel data related to the potential ability of pathogens to evolve aggressiveness, erosion of quantitative head blight resistance in wheat and barley, and applying gene pyramiding which enhances host resistance to FHB infection to achieve durable head blight resistance. Results: Although FHB-resistance resources have been successfully utilized by resistant parents in wheat and barley breeding programs globally, this policy does not ensure high resistance to FHB since resistance will erode due to aggressiveness shifts of the head blight population. The increasing practice of monoculture wheat and barley cultivation has perhaps raised the rate of head blight pathogen evolution and obligated the natural balance shifting in favor of the pathogen, creating more repeated and grave epidemics, even in provinces where FHB has not been earlier recorded. More aggressive FHB populations have emerged in the field and under experimental laboratory conditions. It suggests adaptation followed by a spread of some strains in their environment, including adaptation to FHB-resistant breeds and possible erosion of wheat and barely resistance. Therefore, the pyramiding of several QTLs with high impact in one cereal cultivar may extend durability. Conclusion: If a pyramiding of multiple resistances improving QTL combined with selection against suspected susceptibility factors is achieved in novel cultivars, the evolution of FHB pathogens might be slowed owing to reduced exposure to the pathogen, disruptive selection on FHB populations and subsequently reduced fitness of fusarium fungi. This would stabilize the pathogen population and contribute to the durability of FHB resistance.

Distinct ecological fitness factors coordinated by a conserved Escherichia coli regulator during systemic bloodstream infection

The ability of bacterial pathogens to adapt to host niches is driven by the carriage and regulation of genes that benefit pathogenic lifestyles. Genes that encode virulence or fitness-enhancing factors must be regulated in response to changing host environments to allow rapid response to challenges presented by the host. Furthermore, this process can be controlled by preexisting transcription factors (TFs) that acquire new roles in tailoring regulatory networks, specifically in pathogens. However, the mechanisms underlying this process are poorly understood. The highly conserved Escherichia coli TF YhaJ exhibits distinct genome-binding dynamics and transcriptome control in pathotypes that occupy different host niches, such as uropathogenic E. coli (UPEC). Here, we report that this important regulator is required for UPEC systemic survival during murine bloodstream infection (BSI). This advantage is gained through the coordinated regulation of a small regulon comprised of both virulence and metabolic genes. YhaJ coordinates activation of both Type 1 and F1C fimbriae, as well as biosynthesis of the amino acid tryptophan, by both direct and indirect mechanisms. Deletion of yhaJ or the individual genes under its control leads to attenuated survival during BSI. Furthermore, all three systems are up-regulated in response to signals derived from serum or systemic host tissue, but not urine, suggesting a niche-specific regulatory trigger that enhances UPEC fitness via pleiotropic mechanisms. Collectively, our results identify YhaJ as a pathotype-specific regulatory aide, enhancing the expression of key genes that are collectively required for UPEC bloodstream pathogenesis.

Pathogenicity and anti-infection immunity of animal H3N2 and H6N6 subtype influenza virus cross-species infection with tree shrews

Animal influenza viruses can spread across species and pose a fatal threat to human health due to the high pathogenicity and mortality. Animal models are crucial for studying cross-species infection and the pathogenesis of influenza viruses. Tupaia belangeri (tree shrew) has been emerging as an animal model for multiple human virus infections recently because of the close genetic relationship and phylogeny with humans. So far, tree shrew has been reported to be susceptible to human influenza virus subtype H1N1, avian influenza viruses subtype H9N2, subtype H5N1, and subtype H7N9. However, the pathogenicity, infection, and immunity of swine and land avian influenza viruses with low pathogenicity and the potential to jump to humans remain largely unexplored in the tree shrew model. Previously, our team has successfully isolated the newly emerging swine influenza virus subtype H3N2 (A/Swine/GX/NS2783/2010, SW2783) and avian influenza virus subtype H6N6 (A/CK/ZZ/346/2014, ZZ346). In this study, we observed the pathogenicity, immune characteristics, and cross-species infection potential ability of SW2783 and ZZ346 strains in tree shrew model with 50% tissue culture infective dose (TCID50), hematoxylin and eosin (HE) staining, immunohistochemistry (IHC), real-time quantitative PCR (qRT-PCR) and other experimental methods. Both animal-borne influenza viruses had a strong ability on tissue infection in the turbinate and the trachea of tree shrews in vitro, in which SW2783 showed stronger replication ability than in ZZ346. SW2783 and ZZ346 both showed pathogenic ability with infected tree shrews model in vivo without prior adaptive culture, which mainly happened in the upper respiratory tract. However, the infection ability was weak, the clinical symptoms were mild, and the histopathological changes in the respiratory tract were relatively light. Furthermore, innate immune responses and adaptive immunity were observed in the tree shrew model after the infection of SW2783 and ZZ346 strains. We observed that the unadapted SW2783 and ZZ346 virus could transmit among tree shrews by direct contact. We also observed that SW2783 virus could transmit from tree shrews to guinea pigs. These results indicated that both animal-borne influenza viruses could induce similar pathogenicity and immune response to those caused by human-common influenza viruses. Tree shrews may be an excellent animal model for studying the interaction between the influenza virus and the host and the cross-species infection mechanism of the animal influenza virus.

1220. Public Health Investigations of Water-Related Organisms in Neonatal Intensive Care Units—United States, 2014–2022

Abstract Background Preterm and critically ill infants cared for in neonatal intensive care units (NICUs) are vulnerable to a wide variety of infections. Water use in healthcare settings is a known risk factor for opportunistic pathogen transmission due to the ability of such pathogens to persist in premise plumbing, though facility water risk assessments may also not account for practices within NICUs. We describe Centers for Disease Control and Prevention (CDC) consultations involving NICU patients and water-related organisms to help inform infection prevention and control response. Methods We searched internal CDC records from January 1, 2014, through December 31, 2021, to identify consultations involving investigations of potential or confirmed transmission of water-related organisms in NICU settings. We used available information to determine number of consultations and patients affected, most common organisms implicated, and potential exposure pathways and transmission routes. Results Of 92 consultations involving NICUs in the United States during the study period, we identified 30 consultations (33%) of water-related organism infections or outbreaks; combined, water-related organisms were isolated from 178 patients during these investigations. Serratia marcescens was the organism reported in the greatest number of investigations (n=10, 33%), followed by Pseudomonas spp. and Burkholderia cepacia complex (each n=4, 13%). Definitive transmission routes were not determined for all consultations, though investigations frequently identified concerns with water use in infant activities of daily living, such as bathing or feeding (n=14, 47%). Examples of such exposures unique to the NICU setting included the use of tap water to remove disinfectant residue from humidified isolettes and storage of supplies rinsed in water in infant bath basins to dry. Conclusion Consultations involving water-related organisms are common in the NICU. While clear sources of transmission are not always found, investigations often identified water exposures that may pose infection risks. To protect critically ill infants, hospitals should account for the extensive and unique characteristics of water use in NICUs when developing water management programs. Disclosures All Authors: No reported disclosures.

Cross-Over Pathogenic Bacteria Detected in Infected Tomatoes (Solanum lycopersicum L.) and Peppers (Capsicum annuum L.) in Bulgaria.

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. In total, 26 strains were isolated, identified by MALDI-TOF, and phenotypically characterized. The PCR amplification of the rpoB gene was applied as an approach for the rapid detection of cross-over pathogens in plant samples. A great bacterial diversity was revealed from tomato samples as nine species were identified (Leclercia adecarboxylata, Pseudesherichia vulneris, Enterobacter cancerogenus, Enterobacter cloacae, Enterobacter bugandensis, Acinetobacter calcoaceticus, Pantoea agglomerans, Pantoea ananatis, and Pectobacterium carotovorum). Polymicrobial contaminations were observed in samples T2 (tomato flower) and T10 (tomato fruit). Five species were identified from pepper samples (P. agglomerans, L. adecarboxylata, Pseudomonas sp., Pseudomonas putida, and Enterococcus sp.). Antibiotic resistance patterns were assigned in accordance with EFSA recommendations. All isolates showed varying resistance to the tested antibiotics. The genetic basis for the phenotypic antibiotic resistance was not revealed. No genes for the virulence factors were found among the population. To our knowledge, this is the first overall investigation of tomato and pepper cross-over pathogenic bacterial populations in Bulgaria.

Membrane-Active Cyclic Amphiphilic Peptides: Broad-Spectrum Antibacterial Activity Alone and in Combination with Antibiotics.

We designed a library of 24 cyclic peptides containing arginine (R) and tryptophan (W) residues in a sequential manner [RnWn] (n = 2-7) to study the impact of the hydrophilic/hydrophobic ratio, charge, and ring size on the antibacterial activity against Gram-positive and Gram-negative strains. Among peptides, 5a and 6a demonstrated the highest antimicrobial activity. In combination with 11 commercially available antibiotics, 5a and 6a showed remarkable synergism against a large panel of resistant pathogens. Hemolysis (HC50 = 340 μg/mL) and cell viability against mammalian cells demonstrated the selective lethal action of 5a against bacteria over mammalian cells. Calcein dye leakage and scanning electron microscopy studies revealed the membranolytic effect of 5a. Moreover, the stability in human plasma (t1/2 = 3 h) and the negligible ability of pathogens to develop resistance further reflect the potential of 5a for further development as a peptide-based antibiotic.

Evaluation of Pathogenic Fusarium spp. Associated with Soybean Seed (Glycine max) in Hubei Province, China.

Soybean (Glycine max L.) seeds showing serious symptoms from rotted pods were collected from fields during the harvesting period (July to August 2020) in Taihu Farm, Jingzhou City, Hubei Province, China. Fusarium strains were frequently encountered during fungal isolation. According to the morphology and prepathogenicity tests, six strains showing variable effects on the seeds were selected for identification based on morphology and multilocus phylogenetic analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA, translation elongation factor (EF-1α), calmodulin (CAM), β-tubulin (TUB), and partial RNA polymerase second largest subunit (RPB2), and to evaluate the pathogenic abilities on seed, root, and pod. The results indicated that the strains contained two species (Fusarium fujikuroi and F. proliferatum) in the Fusarium fujikuroi species complex (FFSC) and two species (F. luffae and F. sulawense) from the Fusarium incarnatum-equiseti species complex (FIESC). The two species of FFSC were more aggressive than those of FIESC on soybean seed, root, and pod. Among the strains, F. proliferatum YZU 201408 exhibited the most pathogenicity on all tests, with 72.2 to 90% disease severity.

Assessment of the biofilm-forming ability on solid surfaces of periprosthetic infection-associated pathogens

Biofilm formation is one of the leading causes of complications after surgery in clinical settings. In this study, we profiled the biofilm-forming ability of various periprosthetic infection-associated pathogens on medically relevant surfaces, polystyrene (PS) and titanium (Ti). We also explored how a specific environmental stressor, epigallocatechin gallate (EGCG), affected biofilm formation. First, Congo red tests revealed that all microorganisms formed biofilms within 72 h. Then, the amounts of biofilm formation on PS at 24, 48 and 72 h and also on a Ti plate for 72 h were determined. Some microbes preferred one surface over the other, whereas other microbes formed consistent levels of biofilm regardless of the surface material. Staphylococcus lugdunenensis was the most potent, while Enterococcus faecalis and Staphylococcus aureus were the weakest. Bacterial adhesion to hydrocarbon (BATH) tests indicated that the biofilm-forming abilities were not directly correlated with cell surface hydrophobicity (CSH). Finally, an external signal, EGCG, was applied to challenge the biofilm formation of each microorganism. EGCG regulated each microorganism’s ability differently, though the change was consistent across surfaces for most pathogens. This study can help a better understanding of a broad spectrum of periprosthetic infection-associated pathogens by relative comparison of their biofilm-forming abilities.

MULTI-STATE OCCUPANCY MODEL ESTIMATES PROBABILITY OF DETECTION OF AN AQUATIC PARASITE USING ENVIRONMENTAL DNA: PSEUDOLOMA NEUROPHILIA IN ZEBRAFISH AQUARIA.

Detecting the presence of important parasites within a host and its environment is critical to understanding the dynamics that influence a pathogen's ability to persist, while accurate detection is also essential for the implementation of effective control strategies. Pseudoloma neurophilia is the most common pathogen reported in zebrafish (Danio rerio) research facilities. The only assays currently available for P. neurophilia are through lethal sampling, often requiring euthanasia of the entire population for accurate estimates of prevalence in small populations. We present a non-lethal screening method to detect P. neurophilia in tank water based on the detection of environmental DNA (eDNA) from this microsporidium, using a previously developed qPCR assay that was adapted to the digital PCR (dPCR) platform to complement current surveillance protocols. Using the generated dPCR data, a multi-state occupancy model was also implemented to predict the probability of detecting the microsporidium in tank water under different flow regimes and pathogen prevalence. The occupancy model revealed that samples collected in static conditions were more informative than samples collected from flow-through conditions, with a probability of detection at 80% and 47%, respectively. There was also a positive correlation between the frequency of detection in water and prevalence in fish based on qPCR.

Evaluation of the pathogenicity of endophytic fungi isolated from spines of rattan (Calamus castaneus) against other plant hosts

In this study, we sought to determine the pathogenic ability of endophytic fungi recovered from the spines of Calamus castaneus, a common rattan palm growing in the forests of Peninsula Malaysia. Ten endophytic fungal isolates were selected for pathogenicity tests: Colletotrichum boninense, Colletotrichum fructicola, Colletotrichum cliviae, Diaporthe hongkongensis, Diaporthe arengae, Diaporthe cf. nobilis, Neopestalotiopsis saprophytica, Neopestalotiopsis formicarum, Fusarium solani and Fusarium oxysporum. These endophytes were tested against leaves of bertam (Eugeissona sp.), oil palm (Elaeis guineensis) and mango (Mangiferae indica) and the fruits of chilli (Capsicum annum), tomato (Solanum lycopersicum) and banana (Musa acuminata). The fungal isolates showed infectivity against bertam, oil palm and mango leaves with degrees of virulence ranging from low to moderate, whereas infectivity against chilli, tomato and banana ranged from low to very high. Fungal endophytes isolated from the spines of C. castaneus are pathogenic to different crop plants with differing degrees of virulence or aggressiveness. Spines of C. castaneus can harbour fungal pathogens of a number of different crops as endophytes. The ability of the fungal endophytes to colonize and infect different crops demonstrate their importance towards agricultural crops. There is a possibility the endophytes behave as latent pathogen. When conditions become favourable, the fungal endophytes transform to pathogenic form and potentially infect other plants.

The role of mucus in adhesion and invasion of foodborne pathogens: challenges in current human intestinal model

Cell adhesion and invasion are the fundamental processes of bacterial pathogenicity that govern their probable transmission pathways. The gastrointestinal mucosa, which is lined with epithelial cells, is the primary route used by the foodborne pathogen to reach systemic organs and tissues. This mucosa is protected by a layer of continually secreted mucus, which is thought to be the initial line of defence against pathogen invasion. Studies on the adhesion and invasion ability of foodborne pathogens using Caco-2 monoculture have been comprehensively reported. This cell line, however, is classified as non-mucusproducing cells. Since the mechanism of adhesion and invasion is largely depending on the presence of mucus, the use of this cell line to study how foodborne pathogens cross the intestinal barrier has raised concerns as the establishment of the typical components that define the intestine is not established. Therefore, HT29 (low-mucus producing) and its sub -population HT29-MTX (high-mucus producing) monoculture cells have been chosen in various investigations to study the role of mucus in bacterial adhesion and invasion. However, employing monoculture as a model to study how foodborne pathogens cross the intestinal barrier faces significant challenges in mimicking the complexity of intact threedimensional (3D) in vivo conditions. To address this issue, 3D co-culture models of the human intestine have been established as an alternative to the monoculture epithelial cells, allowing more accurate prediction of adhesion/invasion mechanisms. Thus, this article reviewed the role of mucus in adhesion/invasion studies of foodborne pathogens and discusses how the employment of diverse in vitro models impacts the properties of hostpathogen interactions.

RESEARCH OF THE PHYTOTOXIC EFFECT OF TEBUCONAZOLE, РROTHIOCONAZOLE, FLUDIOXONYL AND BASED ON THEM PRODUCTS ON THE GERMINATION POWER AND GROWTH OF SEEDLINGS OF WHEAT AND WHITE MUSTARD

The elaboration of new fungicidal protectants is an urgent issue due to the ability of pathogens to develop resistance. This fact contributes to the constant production of new protectants, so it carries an additional environmental impact. The main problem of development of new fungicides is choice of methods for identifying of optimal combinations and concentrations of fungicides. The optimization of the composition of fungicides is aimed to reduce the amount of active substances due to the synergistic effect. The use of fungicidal preparations with a reduced amount of active substances carries a lower environmental impact and gives a greater economic effect.
 One of the main problems in the application of fungicides is the phytotoxicity of the fungicides in relation to the protected plants. Phytotoxicity in general is the ability of pesticides or other substances to have a depressing (toxic) effect on plants. This problem is solved through researches of the germination of seedlings during the development of protectants.
 Researches of the germination power of seeds of soft winter wheat and white mustard after treatment with tebuconazole, рrothioconazole, and fludioxonyl were considered in the article. The main traits of the influence of the named substances on the germination of wheat grains and white mustard seeds, and morphological features of wheat seedlings, such as the length of their roots and shoots are revealed.
 In accordance to the results of the research, combinations of active substances (a.s.) that provide high effectiveness against the causative agents of diseases, and also do not have a phytotoxic effect on the protected culture have been determined.
 The aim of the work was the identification of traits of the phytotoxic effect of tebuconazole, рrothioconazole, fludioxonyl in the combination of seed protectants which are used to protect seedlings from plant diseases.
 Materials and methods. An assessment of the effect of three active substances of fungicides on wheat of the Grom cultivar and white mustard was given. The analysis was carried out in two replications for 48 possible combinations of tebuconazole, рrothioconazole, and fludioxonyl as well as fot two control variants. The ratio of normal, infected, abnormal and non-germinated seeds was analyzed.
 Results. According to the realized studies, tebuconazole has the greatest suppressive effect on germination and growth of shoots. Prothioconazole had no effect on germination, but it had a stimulating effect on the development and growth of wheat’s roots and shoots. With the combined action of prothioconazole and fludioxonyl, the greatest decrease in germination of wheat was observed.
 Conclusion. The possible phytotoxic effect, which depends on the dose of the protectant, should be taken into account when choosing a protectant and developing combined products. So the results of research demonstrated that the following combinations had no phytotoxic effect on protected plants: tebuconazole with рrothioconazole 5:10 and 5:15, tebuconazole with fludioxonyl 5:10, рrothioconazole with fludioxonyl 5:10.