Dominant Pathogen Research Articles

Early warning of Diaporthe infection in kiwifruit soft rot by plasmonic dimer-enhanced Raman spectroscopy.

Diaporthe genus is the dominant pathogens of kiwifruit soft rot with long incubation period and rapid onset and very hard to detect in advance. It is of great significance to develop point-of-care tests for disease prevention and field management. Here we screen a pair of genus-level primers for constructing plasmonic dimer Rayleigh/Raman spectroscopy, which enables rapid, specific, and sensitive detection of Diaporthe genus in real kiwifruits. Dark-filed Rayleigh scattering clearly visualizes the target-induced dimer assembly of nanoprobes. Plasmonic dimer-enhanced Raman spectroscopy has high specificity for 12 common isolates of Diaporthe genus in one batch samples with highly accurate results and much higher sensitivity than polymerase chain reaction (PCR). It realizes the recognition of Diaporthe infection at an early stage of 24h when the kiwifruits do not have any noticeable symptoms. It demonstrates a bright prospect of point-of-care tests for early warning of kiwifruit soft rot infection and quality control.

Haemophilus influenzae Protein D antibody suppression in a multi-component vaccine formulation.

Nontypeable Haemophilus influenzae (NTHi) has emerged as a dominant mucosal pathogen causing acute otitis media (AOM) in children, acute sinusitis in children and adults, and acute exacerbations of chronic bronchitis in adults. Consequently, there is an urgent need to develop a vaccine to protect against NTHi infection. A multi-component vaccine will be desirable to avoid emergence of strains expressing modified proteins allowing vaccine escape. Protein D (PD), outer membrane protein (OMP) 26, and Protein 6 (P6) are leading protein vaccine candidates against NTHi. In pre-clinical research using mouse models, we found that recombinantly expressed PD, OMP26, and P6 induce robust antibody responses after vaccination as individual vaccines, but when PD and OMP26 were combined into a single vaccine formulation, PD antibody levels were significantly lower. We postulated that PD and OMP26 physiochemically interacted to mask PD antigenic epitopes resulting in the observed effect on antibody response. However, column chromatography and mass spectrometry analysis did not support our hypothesis. We postulated that the effect might be in vivo through the mechanism of protein vaccine immunologic antigenic competition. We found when PD and OMP26 were injected into the same leg or separate legs of mice, so that antigens were immunologically processed at the same or different regional lymph nodes, respectively, antibody levels to PD were significantly lower with same leg vaccination. Different leg vaccination produced PD antibody levels quantitatively similar to vaccination with PD alone. We conclude that mixing PD and OMP26 into a single vaccine formulation requires further formulation studies.

Multi-Costimulatory Pathways Drive the Antagonistic Pseudoalteromonas piscicida against the Dominant Pathogenic Vibrio harveyi in Mariculture: Insights from Proteomics and Metabolomics.

Vibrio harveyi is the dominant pathogen in mariculture, and biocontrol of this pathogen using antagonistic probiotics is a long-standing biological challenge. Here, Pseudoalteromonas piscicida WCPW15003 as a probiotic effectively antagonized dominant pathogenic V. harveyi in a mariculture, with a growth-of-inhibition ratio of 6.3 h-1. The antagonistic activities of cells and intracellular components of WCPW15003 made a greater contribution to the antagonistic process than did extracellular metabolites and caused the dominance of WCPW15003 during the antagonistic process in vitro. WCPW15003 was safe for the pearl gentian grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus) and, as a consequence of the antagonistic effect on V. harveyi, protected the fish from an immune response in vivo. A comprehensive combined proteomics and metabolomics analysis of antagonistic WCPW15003 and pathogenic V. harveyi in a coculture compared to a monoculture was performed to investigate the antagonistic molecular mechanisms. The results showed that during the antagonistic process, WCPW15003 in a coculture had significantly downregulated metabolic pathways for histidine metabolism, arginine biosynthesis, and phenylalanine metabolism, and upregulated glycerophospholipid metabolism, leading to a competitive advantage against the co-occurring species, V. harveyi. This defined a mechanism by which multi-costimulatory pathways drove P. piscicida WCPW15003 against V. harveyi. IMPORTANCE V. harveyi as a dominant pathogen has become a major hazard in mariculture development and seafood safety, and biocontrol of this pathogen using antagonistic probiotic agents is a long-standing biological challenge. P. piscicida WCPW15003 has promise as a novel, safe, and effective bioagent for specifically inhibiting dominant pathogenic V. harveyi and protects mariculture animals from infection by this pathogen by moderating the host immune response, which is heavily driven by multi-costimulatory pathways in a coculture of WCPW15003 and V. harveyi. This work identified a direction for comprehensively elucidating the molecular mechanism of WCPW15003 antagonism against the dominant pathogen in mariculture using modern molecular biology techniques and provided deep insights into the advantages and potential of this antagonistic probiotic against V. harveyi for the construction of an environmentally friendly, recirculating mariculture system.

Biological Control of Melon Continuous Cropping Obstacles: Weakening the Negative Effects of the Vicious Cycle in Continuous Cropping Soil.

The continuous cropping obstacles of melons have become increasingly serious in recent years. To investigate this, we explored the effects and mechanisms of Bacillus subtilis C3 in control of the continuous cropping obstacles of melon. We provide a novel interaction model of the occurrence factors of continuous cropping obstacles. The dominant pathogen isolated from melon soil was Fusarium. Their hyphae were used as food to cultivate root-knot nematodes. The main phenolic acids in melon soil promoted the growth of Fusarium and indirectly increased the number of root-knot nematodes, but they also had direct toxic effects on melon root-knot nematodes. The simultaneous inoculation of the three had the strongest inhibitory effect on melon seedlings, while the inhibitory effect of paired inoculation was weaker than that of single inoculation. Therefore, the three balance each other, forming a vicious cycle. Bacillus subtilis C3 weakened the negative effects of this cycle on melon by eliminating phenolic acids and inhibiting the growth of Fusarium and root-knot nematodes. Simultaneously, they also alleviated the continuous cropping obstacles of melon by improving the composition and structure of the rhizosphere microbial community. Our results might be useful for the effective control of the continuous cropping obstacles of melon. IMPORTANCE The soil environment, crop growth and fruit quality of melons are negatively affected by long-term continuous cropping. It is important to study the mechanism of continuous cropping obstacles and their biological control. In this study, we propose a novel interaction model of the occurrence factors of continuous cropping obstacles. The dominant phenolic acids, pathogenic fungi, and root-knot nematodes from melon soil balance each other, forming a vicious cycle. Bacillus subtilis C3 weakened the negative effects of this cycle on melon by eliminating phenolic acids and inhibiting the growth of Fusarium and root-knot nematodes. In addition, C3 also improved the composition and structure of the melon rhizosphere microbial community. These results advance the study of the occurrence mechanism of continuous cropping obstacles and demonstrate an efficient and environmentally friendly biological control scheme.

Peroxisome Proliferator FpPEX11 Is Involved in the Development and Pathogenicity in Fusarium pseudograminearum.

Fusarium crown rot (FCR) of wheat, an important soil-borne disease, presents a worsening trend year by year, posing a significant threat to wheat production. Fusarium pseudograminearum cv. b was reported to be the dominant pathogen of FCR in China. Peroxisomes are single-membrane organelles in eukaryotes that are involved in many important biochemical metabolic processes, including fatty acid β-oxidation. PEX11 is important proteins in peroxisome proliferation, while less is known in the fungus F. pseudograminearum. The functions of FpPEX11a, FpPEX11b, and FpPEX11c in F. pseudograminearum were studied using reverse genetics, and the results showed that FpPEX11a and FpPEX11b are involved in the regulation of vegetative growth and asexual reproduction. After deleting FpPEX11a and FpPEX11b, cell wall integrity was impaired, cellular metabolism processes including active oxygen metabolism and fatty acid β-oxidation were significantly blocked, and the production ability of deoxynivalenol (DON) decreased. In addition, the deletion of genes of FpPEX11a and FpPEX11b revealed a strongly decreased expression level of peroxisome-proliferation-associated genes and DON-synthesis-related genes. However, deletion of FpPEX11c did not significantly affect these metabolic processes. Deletion of the three protein-coding genes resulted in reduced pathogenicity of F. pseudograminearum. In summary, FpPEX11a and FpPEX11b play crucial roles in the growth and development, asexual reproduction, pathogenicity, active oxygen accumulation, and fatty acid utilization in F. pseudograminearum.

A multicenter epidemiological study of acute bacterial meningitis in children

Objective: To analyze the clinical epidemiological characteristics including composition of pathogens , clinical characteristics, and disease prognosis acute bacterial meningitis (ABM) in Chinese children. Methods: A retrospective analysis was performed on the clinical and laboratory data of 1 610 children <15 years of age with ABM in 33 tertiary hospitals in China from January 2019 to December 2020. Patients were divided into different groups according to age,<28 days group, 28 days to <3 months group, 3 months to <1 year group, 1-<5 years of age group, 5-<15 years of age group; etiology confirmed group and clinically diagnosed group according to etiology diagnosis. Non-numeric variables were analyzed with the Chi-square test or Fisher's exact test, while non-normal distrituction numeric variables were compared with nonparametric test. Results: Among 1 610 children with ABM, 955 were male and 650 were female (5 cases were not provided with gender information), and the age of onset was 1.5 (0.5, 5.5) months. There were 588 cases age from <28 days, 462 cases age from 28 days to <3 months, 302 cases age from 3 months to <1 year of age group, 156 cases in the 1-<5 years of age and 101 cases in the 5-<15 years of age. The detection rates were 38.8% (95/245) and 31.5% (70/222) of Escherichia coli and 27.8% (68/245) and 35.1% (78/222) of Streptococcus agalactiae in infants younger than 28 days of age and 28 days to 3 months of age; the detection rates of Streptococcus pneumonia, Escherichia coli, and Streptococcus agalactiae were 34.3% (61/178), 14.0% (25/178) and 13.5% (24/178) in the 3 months of age to <1 year of age group; the dominant pathogens were Streptococcus pneumoniae and the detection rate were 67.9% (74/109) and 44.4% (16/36) in the 1-<5 years of age and 5-<15 years of age . There were 9.7% (19/195) strains of Escherichia coli producing ultra-broad-spectrum β-lactamases. The positive rates of cerebrospinal fluid (CSF) culture and blood culture were 32.2% (515/1 598) and 25.0% (400/1 598), while 38.2% (126/330)and 25.3% (21/83) in CSF metagenomics next generation sequencing and Streptococcus pneumoniae antigen detection. There were 4.3% (32/790) cases of which CSF white blood cell counts were normal in etiology confirmed group. Among 1 610 children with ABM, main intracranial imaging complications were subdural effusion and (or) empyema in 349 cases (21.7%), hydrocephalus in 233 cases (14.5%), brain abscess in 178 cases (11.1%), and other cerebrovascular diseases, including encephalomalacia, cerebral infarction, and encephalatrophy, in 174 cases (10.8%). Among the 166 cases (10.3%) with unfavorable outcome, 32 cases (2.0%) died among whom 24 cases died before 1 year of age, and 37 cases (2.3%) had recurrence among whom 25 cases had recurrence within 3 weeks. The incidences of subdural effusion and (or) empyema, brain abscess and ependymitis in the etiology confirmed group were significantly higher than those in the clinically diagnosed group (26.2% (207/790) vs. 17.3% (142/820), 13.0% (103/790) vs. 9.1% (75/820), 4.6% (36/790) vs. 2.7% (22/820), χ2=18.71, 6.20, 4.07, all P<0.05), but there was no significant difference in the unfavorable outcomes, mortility, and recurrence between these 2 groups (all P>0.05). Conclusions: The onset age of ABM in children is usually within 1 year of age, especially <3 months. The common pathogens in infants <3 months of age are Escherichia coli and Streptococcus agalactiae, and the dominant pathogen in infant ≥3 months is Streptococcus pneumoniae. Subdural effusion and (or) empyema and hydrocephalus are common complications. ABM should not be excluded even if CSF white blood cell counts is within normal range. Standardized bacteriological examination should be paid more attention to increase the pathogenic detection rate. Non-culture CSF detection methods may facilitate the pathogenic diagnosis.

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase.

Sufferers of cystic fibrosis are at significant risk of contracting chronic bacterial lung infections. The dominant pathogen in these cases is mucoid Pseudomonas aeruginosa. Such infections are characterised by overproduction of the exopolysaccharide alginate. We present herein the design and chemoenzymatic synthesis of sugar nucleotide tools to probe a critical enzyme within alginate biosynthesis, GDP-mannose dehydrogenase (GMD). We first synthesise C6-modified glycosyl 1-phosphates, incorporating 6-amino, 6-chloro and 6-sulfhydryl groups, followed by their evaluation as substrates for enzymatic pyrophosphorylative coupling. The development of this methodology enables access to GDP 6-chloro-6-deoxy-ᴅ-mannose and its evaluation against GMD.

Development of a rapid neutralization testing system for Rhinovirus C15 based on the enzyme-linked immunospot assay.

Human Rhinoviruses (RVs) are dominant pathogens causing a wide range of respiratory tract diseases, posing a huge threat to public health worldwide. Viruses belonging to the RV-C species are more likely to cause severe illnesses and are strongly associated with asthma onset or exacerbations than RV-A or RV-B. Rapid and sensitive detection of neutralizing antibodies (NAbs) against RV-C can promote the development of vaccines and antiviral drugs and help in the diagnosis of viral infection. In this study, a rapid neutralization testing system for RV-C15, based on an enzyme-linked immunospot assay (Nt-ELISPOT) was developed. A monoclonal antibody (MAb), named 9F9, with high binding efficacy for RV-C15 conjugated to horseradish peroxidase (HRP), was used to detect RV-C15-infected cells at a concentration of 2 μg/ml. The optimal infectious dose of RV-C15 was set at 1 × 104 TCID50/well and the cells were fixed with 0.5% formaldehyde diluted in PBS after incubation for 20 h. Compared with the traditional cytopathic effect (CPE)-based neutralization assay (Nt-CPE), Nt-ELISPOT significantly shortened the detection period and showed good consistency with the detection of neutralizing titers of both sera and NAbs. Using Nt-ELISPOT, three anti-RV-C15 NAbs were obtained with IC50 values of 0.16, 0.27, and 11.8 μg/ml, respectively. Moreover, 64 human serum samples collected from a wide range of age groups were tested for NAb against RV-C15 by Nt-ELISPOT. The total seroprevalence was 48.4% (31/64) and the positive rate was lowest in the group under 6 years old. Thus, the Nt-ELISPOT established in this study can be used as a high-throughput and rapid neutralization assay for the screening of NAbs and for seroepidemiological investigation against RV-C15.

Genome-wide association mapping of septoria nodorum blotch resistance in Nordic winter and spring wheat collections.

A new QTL for SNB, QSnb.nmbu-2AS, was found in both winter and spring wheat panels that can greatly advance SNB resistance breeding Septoria nodorum blotch (SNB), caused by the necrotrophic fungal pathogen Parastagonospora nodorum, is the dominant leaf blotch pathogen of wheat in Norway. Resistance/susceptibility to SNB is a quantitatively inherited trait, which can be partly explained by the interactions between wheat sensitivity loci (Snn) and corresponding P. nodorum necrotrophic effectors (NEs). Two Nordic wheat association mapping panels were assessed for SNB resistance in the field over three to four years: a spring wheat and a winter wheat panel (n = 296 and 102, respectively). Genome-wide association studies found consistent SNB resistance associated with quantitative trait loci (QTL) on eleven wheat chromosomes, and ten of those QTL were common in the spring and winter wheat panels. One robust QTL on the short arm of chromosome 2A, QSnb.nmbu-2AS, was significantly detected in both the winter and spring wheat panels. For winter wheat, using the four years of SNB field severity data in combination with five years of historical data, the effect of QSnb.nmbu-2AS was confirmed in seven of the nine years, while for spring wheat, the effect was confirmed for all tested years including the historical data from 2014 to 2015. However, lines containing the resistant haplotype are rare in both Nordic spring (4.0%) and winter wheat cultivars (15.7%), indicating the potential of integrating this QTL in SNB resistance breeding programs. In addition, clear and significant additive effects were observed by stacking resistant alleles of the detected QTL, suggesting that marker-assisted selection can greatly facilitate SNB resistance breeding.

Talaromyces marneffei is the Persistent Overwhelming Bloodstream Infection Pathogen Among HIV Inpatients in Fujian, China

PurposeThis study aimed to investigate the epidemiology and etiological spectrums of BSI in Fujian over the past 6 years in the post antiretroviral treatment (ART) era.MethodsA retrospective, observational study was conducted to include positive BSI inpatients with HIV between September 2015 and August 2021 in Mengchao Hepatobiliary Hospital of Fujian Medical University, the largest designated HIV/AIDS care hospital in Fujian, China. Demographic data and laboratory data including gender, age, blood cell counts, biochemistry results, CD4 and CD8 cell counts, HIV-RNA loads, pathogen isolates, procalcitonin (PCT) levels and c-reactive protein (CRP) levels were collected. Continuous variables were expressed as median (range) and Kruskal–Wallis or Mann–Whitney test was used to analyze the differences between groups. Categorical data were expressed as numbers (percentage) and the differences between groups were analyzed by Pearson’s chi-squared test.ResultsIn total, 3681 HIV inpatients with blood culture data were included and 683 strains identified from 646 inpatients were further analyzed. The median age of patients was 38 years and male accounted for 86.84%. The pooled prevalence of BSI was 18.55% (12.01%–22.36% during the six-year period). The overall isolated rate of Talaromyces marneffei (TM) in blood culture was 12.42% (8.3%–15.00% during the study period). TM was the persistent dominant BSI pathogen from 2015 to 2021 (accounting for 63.04% to 71.43%), followed by Cryptococcus neoformans (responsible for 10.00% to 20.83%). Compared to patients with other organisms BSI, those with TM BSI were younger and had lower CD4 counts, WBC counts, HB and CRP level, but higher HIVRNA loads.ConclusionBSI is still a major problem in the post ART era in hospitalized patients with HIV/AIDS in Fujian, China. TM is the predominant pathogen. This underlines the importance of an early diagnosis of opportunistic pathogen to avoid BSI in HIV-infected populations with a low immune status.

Extra benefit of microalgae in raw piggery wastewater treatment: pathogen reduction

BackgroundMonitoring microbial communities especially focused on pathogens in newly developed wastewater treatment systems is recommended for public health. Thus, we investigated the microbial community shift in a pilot-scale microalgal treatment system for piggery wastewater.ResultsMicroalgae showed reasonable removal efficiencies for COD and ammonia, resulting in higher transparency of the final effluent. Metagenome and microbial diversity analyses showed that heterotrophic microalgal cultivation barely changed the bacterial community; however, the mixotrophic microalgal cultivation induced a sudden change. In addition, an evaluation of risk groups (RGs) of bacteria showed that raw piggery wastewater included abundant pathogens, and the microalgal treatment of the raw piggery wastewater decreased the RG2 pathogens by 63%. However, co-cultivation of microalgae and the most dominant RG2 pathogen, Oligella, showed no direct effects between them.ConclusionsThus, a microbial interaction network was constructed to elucidate algae-bacteria interrelationships, and the decrease in Oligella was indirectly connected with microalgal growth via Brevundimonas, Sphingopyxis, and Stenotrophomonas. In a validation test, 3 among 4 connecting bacterial strains exhibited inhibition zones against Oligella. Therefore, we showed that microalgal wastewater treatment causes a decrease in RG2 bacteria, which is an indirect impact of microalgae associated with bacteria.Graphical 9xuCqXStUBwsH8dUwtqkoYVideo abstract

Retromer subunit, CfVps35 is required for growth development and pathogenicity of Colletotrichum fructicola

BackgroundTea oil is widely used as edible oil in China, which extracted from the seeds of Camellia oleifera. In China, the national oil-tea camellia planting area reached 4.533 million hectares, the output of oil-tea camellia seed oil was 627 000 tons, and the total output value reached 18.3 billion dollars. Anthracnose is the common disease of Ca. oleifera, which affected the production and brought huge economic losses. Colletotrichum fructicola is the dominant pathogen causing anthracnose in Ca. oleifera. The retromer complex participates in the intracellular retrograde transport of cargos from the endosome to the trans-Golgi network in eukaryotes. Vacuolar protein sorting 35 is a core part of the retromer complex. This study aimed to investigate the role of CfVps35 in C. fructicola.ResultsThe CfVPS35 gene was deleted, resulting in reduced mycelial growth, conidiation, and response to cell wall stresses. Further analysis revealed that CfVps35 was required for C. fructicola virulence on tea oil leaves. In addition, the ΔCfvps35 mutant was defective in glycogen metabolism and turgor during appressorium development.ConclusionThis study illustrated that the crucial functions of CfVps35 in growth, development, and pathogenicity.

Pathogen distribution and risk factors of bacterial and fungal infections after liver transplantation.

Liver transplant recipients have a high rate of postoperative infection, and identification of patients at high risk for bacterial and fungal infections will help prevent disease and improve long-term outcomes for them. This study aims to understand the composition, distribution, prognosis of bacterial and fungal infections within 2 months after liver transplantation and to analyze their risk factors. The data of pathogen composition, distribution, and prognosis of bacterial and fungal infections among liver transplant recipients in the Third Xiangya Hospital of Central South University from May 2020 to October 2021 were collected, and the risk factors for these infections were analyzed. A total of 106 episodes of bacterial or fungal infections occurred in 71.4% of liver transplant recipients (75/105). Gram-negative bacteria were the dominant pathogenic bacteria (49/106, 46.2%), followed by Gram-positive bacteria (31/106, 29.2%). The most common Gram-negative bacterium was Acinetobacter baumannii (13/106, 12.3%). The most common Gram-positive bacterium was Enterococcus faecium (20/106, 18.9%). The most common infections were pulmonary (38/105, 36.2%) and multiple site infections (30/105, 28.6%). Six (6/105, 5.7%) patients with infections died within 2 months after liver transplantation. Univariate analysis showed that the model for end-stage liver disease (MELD) score ≥25, antibiotic use within half a month before transplantation, infections within 2 months prior to transplantation, intraoperative red blood cell infusion≥8 U, indwelling urinary tract catheter ≥4 days after transplantation, and the dosage of basiliximab use ≥40 mg were associated with infections. Multivariate logistic regression analysis revealed that only infections within 2 months prior to transplantation (OR=5.172, 95% CI 1.905-14.039, P<0.01) was an independent risk factor for bacterial and fungal infections after liver transplantation. Postoperative bacterial and fungal infections were reduced in liver transplant recipients receiving basiliximab ≥40 mg (OR=0.197, 95% CI: 0.051-0.762, P<0.05). The incidence of bacterial and fungal infections is high in the early stage after liver transplantation, and the mortality after infection is significantly higher than that of non-infected patients. The most common infection is respiratory infection, and the dominant pathogens is Gram-negative bacteria. Patients infected within 2 months prior to liver transplantation are prone to bacterial and fungal infections. Standard use of basiliximab can reduce the incidence of infections after liver transplantation.

Changing Geographic Ranges of Human Biting Ticks and Implications for Tick-Borne Zoonoses in North America

Ticks and tick-borne pathogens are increasing public health threats due to emergence of novel pathogens, expanding geographic ranges of tick vectors, changing ecology of tick communities, as well as abiotic and biotic influences on tick–host–pathogen interactions. This review examines the major human-biting ixodid tick species and transmitted pathogens of North America. Topics addressed include current and projected tick geographic ranges, potential risks for introduction of tick transmitted microbes into those regions, and drivers for these events. Health care providers, public health authorities, and the general public need to be aware of existing, resurging, and emerging tick and tick-borne disease threats. Knowing which ticks and tick-borne pathogens are present is foundational to understanding and responding to these threats. Dominant tick species and pathogens remain major foci of research, while limited attention has been directed to other human-biting ticks for decades, resulting in questions about current distributions, population sizes, and diversity of infectious agents they are capable of transmitting. Significant threats due to invasive ticks are considered. Recommendations are made for establishment of a sustained North America network for surveillance of ticks, characterization of their microbiomes and viromes, and for support of tick and tick-borne disease ecology research.

The role of nitric oxide synthase and cystatin C in the mechanisms of antimicrobial protection in children with urinary tract infections considering the etiological factor

The aim of the study was to investigate the main etiological factors of urinary tract infections in children, the role of nitric oxide synthase and cystatin C in the mechanisms of antimicrobial protection in children with acute and chronic urinary tract infections. Materials and methods. The study groups consisted of 84 children (mean age – 10.0 ± 1.3 years). The main group was divided into subgroups: the first subgroup – 17 children with acute pyelonephritis, the second subgroup – 21 patients with chronic pyelonephritis, the third subgroup – 16 patients with acute cystitis, the fourth subgroup – 10 patients with unspecified urinary tract infections. The control group consisted of 20 relatively healthy children. The levels of inducible NO-synthase (NOS2) and cystatin C were measured by enzyme-linked immunosorbent assay. The etiological pathogen was identified in the urine of 200 patients with urinary tract infections. Results. Escherichia coli was identified as the dominant pathogen in 46.7 % of cystitis patients and in 66.6 % of chronic pyelonephritis patients. The next most frequently detected etiological agent in children with acute (27.3 % of cases) and chronic (25.6 %) pyelonephritis and unspecified urinary tract infection (32.2 %) was Enterococcus faecium. Proteus mirabilis was found in 26.6 % of patients with cystitis. The level of NOS2 in all the studied subgroups was significantly higher than that in the control group (P &lt; 0.01). A statistically significant increase in the level of cystatin C in the main group (P &lt; 0.05) was determined. The cystatin C-to-NOS2 ratios in the studied subgroups were 1.5–2.0 times lower than those in the control group (P &lt; 0.05). Conclusions. The change in the spectrum of pathogens has been determined, which was a premise of the need for constant bacteriological monitoring. The development of the primary inflammatory process in the urinary tract occurred amidst a certain dysfunction of the immune system, which was manifested in an insufficient quantitative response of cystatin C, as well as high serum levels of inducible NO-synthase in the patients.

Pyrenophora teres: Population structure, virulence and aggressiveness in Southern Russia

The barley net blotch agent Pyrenophora teres (Died) Drechs. is one of the dominant fungal pathogens in agricultural crops worldwide. Here we aim to study the aggressiveness and virulence of P. teres populations collected at different ontogenesis stages (BBCH 30 and BBCH 47) from winter barley cultivars of various resistance types: moderately resistant, moderately susceptible and highly susceptible. We observed a direct proportional relationship between cultivar resistance and the aggressiveness of P. teres populations collected in both growth phases of the host plant. The isolates collected at an early stage of host plant development have a large difference in aggressiveness criteria: colony growth rate, sporulation intensity, latency period, plant damage degree, and the number of identified races. At the BBCH 30 growth stage, the growth rate of fungus colonies selected from a resistant cultivar is 1.2 times higher than that of a susceptible cultivar. The growth rate of colonies selected from resistant and susceptible cultivars in the earlier BBCH 30 stage is 1.04 times higher than the growth rate of colonies selected from the later phase. The sporulation intensity of fungal populations selected from a resistant cultivar is higher than that of populations selected from a susceptible cultivar (for BBCH 30–5.4 times, for BBCH 47–4.0 times); and it is 1.3 times higher in an earlier phase of plant development. Correlation between colony growth rate and spore formation rate in the BBCH 30 is r = 0.4. A high correlation level (r = 0.9) and notable difference between the variants were revealed when studying the duration of the latent period. The average value of plant damage by the P. teres from resistant cultivar is 4 times higher than from the susceptible cultivar in the BBCH 30 stage; and 12 times – in the BBCH 47 stage. There is a moderate negative correlation between the plant damage degree and the number of races identified from the fungal population, r = −0.59 for the BBCH 30, r = −0.8 for the BBCH 47. The number of races identified from P. teres populations collected in the late phase of plant growth was one third less. Our study helped to acquire new knowledge about intrapopulation processes under the influence of various factors – plant growth stage and cultivar genotype. The results obtained are the basis for the development of adaptive-integrated techniques for managing populations of the hemibiotrophic pathogen, barley net blotch.

Breeding Tools for Assessing and Improving Resistance and Limiting Mycotoxin Production by Fusarium graminearum in Wheat

The recently adopted conservation and minimum tillage practices in wheat-production systems coupled with the concomitant warming of the Earth are believed to have caused the upsurges in Fusarium head blight (FHB) prevalence in major wheat-producing regions of the world. Measures to counter this effect include breeding for resistance to both initial infection of wheat and spread of the disease. Cases of mycotoxicosis caused by ingestion of wheat by-products contaminated with FHB mycotoxins have necessitated the need for resistant wheat cultivars that can limit mycotoxin production by the dominant causal pathogen, Fusarium graminearum. This manuscript reviews breeding tools for assessing and improving resistance as well as limiting mycotoxin contamination in wheat to reflect on the current state of affairs. Combining these aspects in wheat research and development promotes sustainable quality grain production and safeguards human and livestock health from mycotoxicosis.

First Report of Corynespora cassiicola Causing Target Spot on Cotton (Gossypium hirsutum) in South India.

Target spot with unusual symptoms was observed in upland cotton at Regional Agricultural Research Station, Lam, Guntur, Andhra Pradesh, India in 2017. Symptoms appeared in about 60-65 days after planting with minute pinhead size light orange to brick red spots that gradually expanded as circular to oval or irregular concentric spots that finally developed as target spot with yellow halo. These symptoms were also observed during 2019-20 and 2020-21 diagnostic field visits at Krishna zone of Andhra Pradesh, India. Frequent showers had intensified disease severity and defoliation of different cultivars (L 1060, RCH 659 BGII, NDLH-1938 and Jaadoo BG II) examined. Leaf bits containing healthy and diseased portions of the specimens were surface sterilized with 0.1% HgCl2 for a minute and rinsed in three changes of distilled water and were placed on PDA at 27±1˚C for pathogen development. Obtained pathogen was purified using single spore isolation technique. Purified colonies exhibited grey colour on top of culture plate and greyish brown on bottom of culture plate with flat, aerial round colonies having fibrous texture with dense mycelium. Conidiophore were indeterminate septate with intermediate branching. Enteroblastic conidiogenous cells produced conidia subhyaline that were solitary or in chains, straight to curved, 83.43±31.73 x 7.61±1.43 µm with 7.27±2.19 pseudospeta. Morphological characteristics of the isolated fungus were consistent with original description of Corynespora cassiicola on cotton (Jones 1961; Fulmer et al., 2012; Conner et al., 2013) which confirmed it as Corynespora morphologically. Pathogenicity test was conducted on popular hybrid Jaadoo BG II using three isolates Lam (CGGL 19001), Koniki (CPIK 19009) and Venkatapuram (CKMB 19011) obtained during 2019-20 survey. After 50 days of sowing conidial suspension containing 1x104 spores per ml was sprayed on healthy plants maintained in pots under protected conditions. Immediately after spraying, the plants were covered with poly propylene covers for 48 h to prevent cross contamination and to ensure humidity for pathogen establishment. Healthy plants sprayed with sterile water served as control. After seven days of incubation, inoculated plants developed brick red spots initially which later developed into target spot. Absence of symptoms in control plants indicated pathogenic nature of the fungus. Pathogen was re-isolated from diseased tissue to confirm its pathogenicity according to Koch's postulates. The identity of the pathogen was further examined using ITS primers. The DNA was isolated from 10 days old culture using CTAB method. Internal transcribed spacer (ITS) region of three isolates were amplified using ITS1 and ITS4 primers and obtained amplicon (550 bp) were used for sequencing. The sequenced data was deposited in NCBI and accession numbers were obtained as MZ314930, MZ314928 and MZ314927. BLAST search in GeneBank revealed 99% homology of CGGL 19001 isolate with sequences of C. cassiicola (accession number of MN393240) while CPIK 19009 and CKMB 19011 isolates showed 100% homology with C. cassiicola in cotton having accession numbers of MN393238, MN228955, MN733135, MN288934 and MN393238. Based on symptoms, fungal morphology, pathogenicity test and ITS sequences obtained, the fungus was identified as C. cassiicola the pathogen of cotton causing target spot disease. Earlier, Sarma and Nayudu (1970) isolated Corynespora from different host plants including cotton but could not prove its pathogenicity on cotton. Later target spot of cotton associated with C. cassiicola had been reported from Central India (Salunkhe et al., 2019) and this is the first report of C. cassiicola in cotton from South India. Hence, this report of C. cassiicola on cotton is the first report from Souh India. Identification of target spot pathogen is very important as it is emerging as a dominant foliar pathogen for which management strategies are to be worked out.

A Small-Molecule Inhibitor of the Anthranilyl-CoA Synthetase PqsA for the Treatment of Multidrug-Resistant Pseudomonas aeruginosa.

ABSTRACTOne of the challenges associated with the treatment of Pseudomonas aeruginosa infections is the high prevalence of multidrug resistance (MDR). Since conventional antibiotics are ineffective at treating such bacterial infections, innovative antibiotics acting upon novel targets or via mechanisms are urgently required. In this study, we identified a quorum sensing inhibitor (QSI), norharmane, that uniquely shows weak antibacterial activity but strongly inhibits pyocyanin production and biofilm formation of MDR P. aeruginosa. Biophysical experiments and molecular docking studies showed that norharmane competes with anthraniloyl-AMP for anthranilyl-CoA synthetase PqsA of P. aeruginosa at the ligand-binding pocket, which is not exploited by current inhibitors, thereby altering transcription regulatory activity. Moreover, norharmane exhibits synergy with polymyxin B. This synergism exhibits a high killing rate, low probability of resistance selection, and minimal cytotoxicity. Notably, norharmane can effectively boost polymyxin B activity against MDR P. aeruginosa-associated infections in animal models. Together, our findings provide novel insight critical to the design of improved PqsA inhibitors, and an effective combination strategy to overcome multiantibiotic bacterial resistance using conventional antibiotics and QSIs.IMPORTANCE Pseudomonas aeruginosa is a dominant hospital-acquired bacterial pathogen typically found in immunocompromised individuals. It is particularly dangerous for patients with chronic lung diseases and was identified as a serious threat for patients in the 2019 Antimicrobial Resistance Threats report (https://www.cdc.gov/drugresistance/biggest-threats.html). In this study, we used activity-based high-throughput screening to identify norharmane, a potent and selective inhibitor of P. aeruginosa PqsA, which is a well-conserved master quorum sensing (QS) regulator in multidrug resistant (MDR) P. aeruginosa. This compound competitively binds anthranilyl-CoA synthetase PqsA at the anthraniloyl-AMP binding domain, which has not been exploited by known inhibitors. Remarkably, norharmane can significantly block the production of the virulence factor, pyocyanin (87%), and biofilm formation (80%) in MDR P. aeruginosa. Furthermore, norharmane is capable of augmenting polymyxin B activity against MDR P. aeruginosa in cell cultures and animal models. Taken together, these results suggest that norharmane may be an effective adjuvant for combating multiantibiotic bacterial resistance.

Culture-confirmed neonatal bloodstream infections and meningitis in South Africa, 2014–19: a cross-sectional study

SummaryBackgroundFew population-level estimates of invasive neonatal infections have been reported from sub-Saharan Africa. We estimated the national incidence risk, aetiology, and pathogen antimicrobial susceptibility for culture-confirmed neonatal bloodstream infections and meningitis in South Africa.MethodsWe conducted a cross-sectional study of neonates (<28 days of life) admitted to neonatal or paediatric wards of 256 public sector health facilities in South Africa during 2014–19. Diagnostic pathology records from Jan 1, 2014, to Dec 31, 2019, were extracted from a national pathology data warehouse. A case was defined as a neonate with at least one positive blood or cerebrospinal fluid culture during a 14-day period. Incidence risk was calculated using annual numbers of registered livebirths. Among the causative pathogens identified, we calculated the proportion of cases attributed to each of them, as well as the rates of antibiotic susceptibility of Gram-positive and Gram-negative bacteria.FindingsAmong 43 438 records of positive cultures, there were 37 631 incident cases of neonatal infection with at least one pathogen isolated. The overall incidence risk of culture-confirmed infections was 6·0 per 1000 livebirths (95% CI 6·0–6·1). The incidence risk of late-onset sepsis (days 3–27 of life) was 4·9 per 1000 livebirths (4·9–5·0) and that of early-onset sepsis (days 0–2 of life) was 1·1 per 1000 livebirths (1·1–1·1); risk ratio 4·4 (95% CI 4·3–4·5). The cause of infection differed by syndrome, timing of infection onset, facility, and province, although Klebsiella pneumoniae (26%), Acinetobacter baumannii (13%), and Staphylococcus aureus (12%) were the dominant pathogens overall. Gram-negative bacteria had declining susceptibility to most antibiotics over the study period.InterpretationWe found a high incidence risk of late-onset sepsis with provincial variations, predominance of K pneumoniae, and declining antibiotic susceptibility among Gram-negative bacteria. This national surveillance in an upper-middle-income country provides a baseline burden of neonatal infections against which the impact of future clinical and public health interventions can be measured.FundingBill & Melinda Gates Foundation.