Levels Of Bacterial Infection Research Articles

Iron-doped nanozymes with spontaneous peroxidase-mimic activity as a promising antibacterial therapy for bacterial keratitis.

The development of non-antibiotic pharmaceuticals with biocompatible and efficient antibacterial properties is of great significance for the treatment of bacterial keratitis. In this study, we have developed antibacterial iron-doped nanozymes (Fe3+-doped nanozymes, FNEs) with distinguished capacity to fight against bacterial infections. The iron-doped nanozymes are composed of Fe3+ doped zeolitic imidazolate framework-8 (Fe/ZIF-8) and polyethylene imide (PEI), which were functionally coated on the surface of Fe/ZIF-8 and imparted the FNEs with improved water dispersibility and biocompatibility. FNEs possess a significant spontaneous peroxidase-mimic activity without the need for external stimulation, thus elevating cellular reactive oxygen species level by catalyzing local H2O2 at the infection site and resulting in bacteria damaged to death. FNEs eliminated 100% of Staphylococcus aureus within 6h, and significantly relieved inflammation and bacterial infection levels in mice bacterial keratitis, exhibiting higher bioavailability and a superior therapeutic effect compared to conventional antibiotic eye drops. In addition, the FNEs would not generate drug resistance, suggesting that FNEs have great potential in overcoming infectious diseases caused by antimicrobial resistant bacteria.

Mycobacterium tuberculosis SecA2-dependent activation of host Rig-I/MAVs signaling is not conserved in Mycobacterium marinum.

Retinoic acid inducible gene I (Rig-I) is a cytosolic pattern recognition receptor canonically described for its important role in sensing viral RNAs. Increasingly, bacterially-derived RNA from intracellular bacteria such as Mycobacterium tuberculosis, have been shown to activate the same host Rig-I/Mitochondrial antiviral sensing protein (MAVS) signaling pathway to drive a type-I interferon response that contributes to bacterial pathogenesis in vivo. In M. tuberculosis, this response is mediated by the protein secretion system SecA2, but little is known about whether this process is conserved in other pathogenic mycobacteria or the mechanism by which these nucleic acids gain access to the host cytoplasm. Because the M. tuberculosis and M. marinum SecA2 protein secretion systems share a high degree of genetic and functional conservation, we hypothesized that Rig-I/MAVS activation and subsequent induction of IFN-β secretion by host macrophages will also be conserved between these two mycobacterial species. To test this, we generated a ΔsecA2 M. marinum strain along with complementation strains expressing either the M. marinum or M. tuberculosis secA2 genes. Our results suggest that the ΔsecA2 strain has a growth defect in vitro but not in host macrophages. These intracellular growth curves also suggested that the calculation applied to estimate the number of bacteria added to macrophage monolayers in infection assays underestimates bacterial inputs for the ΔsecA2 strain. Therefore, to better examine secreted IFN-β levels when bacterial infection levels are equal across strains we plated bacterial CFUs at 2hpi alongside our ELISA based infections. This enabled us to normalize secreted levels of IFN-β to a standard number of bacteria. Applying this approach to both WT and MAVS-/- bone marrow derived macrophages we observed equal or higher levels of secreted IFN-β from macrophages infected with the ΔsecA2 M. marinum strain as compared to WT. Together our findings suggest that activation of host Rig-I/MAVS cytosolic sensors and subsequent induction of IFN-β response in a SecA2-dependent manner is not conserved in M. marinum under the conditions tested.

Improvement of the quality of bacterially infected diffusion juice by application of enzyme preparation Dextrasept 2

The object of the research was diffusion juice obtained from bacterially infected sugar beet roots. The purpose of the work was to establish the laws of changing the quality of diffusion juice in sugar beet production when using the enzyme preparation Dextrasept 2 in the process of extraction of sucrose from bacterially infected sugar beets. As a result of the studies, the dependences of the change in the quality indicators of diffusion juice on the degree of bacterial infection of the root cell juice and the doses of the enzyme preparation Dextrasept 2 were determined. Regression equations are obtained that are suitable for calculating the dose of the applied enzyme preparation Dextrasept 2, depending on the degree of bacterial infection of the cell juice of sugar beet roots, oriented towards achieving the specified values of the quality indicators of diffusion juice. A multicriterial assessment on the Harrington desirability scale ranging from 0.66 to 1.00 confirmed the expediency of the application of enzyme preparation Dextrasept 2 at a dose of 4 to 8 kg per 1,000 ton of sugar beet with a level of bacterial infection within the presence of 2…8 “clouds” (mucous membranes inclusions) in the cell juice of the roots. It was found out that the use of the enzyme preparation improved the technological parameters of diffusion juice, increased sucrose content in it by an average 2 %, which could contribute to improving the quality and yield of white sugar.

Influence of the component composition of nutrient media upon the introduction into the culture in vitro of explants of Prikubanskoe and Kubanskoe Bagryanoe apple varieties

The work reflects the aspects of introducing two varieties of apple trees into the culture in vitro: Prikubanskoe and Kubanskoe Bagryanoe. The aims of study included testing a new disinfection protocol that accurately regulates the content of active chlorine in the disinfecting solution, as well as studying the regenerative ability of explants of apple trees of the Prikubanskoe and Kubanskoe Bagryanoe varieties on different culture medium: Murashige and Skoog (MS) ¼ NH4 NO3 , and Kvorin-Lepuavra (QL). The disinfection protocol used made it possible to obtain an insignificant level of explant contamination with fungal infection in passage zero, which indicates the effectiveness of the tested extraction protocol. The contamination of explants in passage zero by fungal infection was insignificant, which indicates the high efficiency of the sterilizing agent. The level of bacterial infection is higher in the Kubanskoe Bagryanoe variety (21.3 % of the total amount of explants). The influence of the component composition of nutrient media on the primary growth of apple micro-shoots was revealed. The following results were obtained: the yield of viable explants of the Prikubanskoe variety grown on nutrient medium MS ¼ NH4 NO3 was 44,4 %, which is 16,4 % higher than explants grown on QL medium (28 %). Explants of the Kuba nskoe bagryanoe variety, in turn, have a yield of vital microplants grown on MS ¼ NH4 NO3 16.7 %, which is 30.4 % lower than explants grown on QL medium (47.1 %). The combined effect of the genotype and the composition of the nutrient medium on the development of explants was statistically significant for the studied parameters. The share of the cumulative effect of factors of the variety x medium is 74.93 %, the influence of the genotype is 20.72 %. The data obtained indicate the variety specificity of the nutrient medium during clonal micropropagation of these apple varieties.

Modeling cystic fibrosis disease progression in patients with the rare CFTR mutation P67L

BackgroundThe progression of cystic fibrosis (CF) in patients with the rare mutation P67L was examined to determine if it induced a milder form of CF compared to the common severe ΔF508 mutation. MethodsParameters of lung function, level of bacterial infection, nutritional status and hospitalization were used to represent CF progression. Age at diagnosis and pancreatic status were used to assess CF presentation. Analysis of data from the CF Canada Registry collected over a 15-year period included 266 ΔF508/ΔF508 homozygote patients from CF clinics in Atlantic Canada and 26 compound heterozygote patients with the rare P67L mutation from clinics across Canada. ResultsLate age at diagnosis, high incidence of pancreatic sufficiency, maintained Body Mass Index (BMI) with age, delayed life-threatening bacterial infection, and fewer days in hospital were observed for P67L heterozygote patients included in this study. Although the decline of lung function did not differ from ΔF508 homozygotes, the fact that a greater proportion of P67L heterozygotes live to an older age suggests that lung function is not the primary factor determining CF progression for P67L heterozygote patients. ConclusionThe P67L mutation is associated with a mild disease, even when combined with the severe ΔF508 mutation.

Functional Divergence of Two Secreted Immune Proteases of Tomato

Rcr3 and Pip1 are paralogous secreted papain-like proteases of tomato. Both proteases are inhibited by Avr2 from the fungal pathogen Cladosporium fulvum, but only Rcr3 acts as a co-receptor for Avr2 recognition by the tomato Cf-2 immune receptor. Here, we show that Pip1-depleted tomato plants are hyper-susceptible to fungal, bacterial, and oomycete plant pathogens, demonstrating that Pip1 is an important broad-range immune protease. By contrast, in the absence of Cf-2, Rcr3 depletion does not affect fungal and bacterial infection levels but causes increased susceptibility only to the oomycete pathogen Phytophthora infestans. Rcr3 and Pip1 reside on a genetic locus that evolved over 36 million years ago. These proteins differ in surface-exposed residues outside the substrate-binding groove, and Pip1 is 5- to 10-fold more abundant than Rcr3. We propose a model in which Rcr3 and Pip1 diverged functionally upon gene duplication, possibly driven by an arms race with pathogen-derived inhibitors or by coevolution with the Cf-2 immune receptor detecting inhibitors of Rcr3, but not of Pip1.

IgG sera levels against a subset of periodontopathogens and severity of disease in aggressive periodontitis patients: a cross-sectional study of selected pocket sites.

To evaluate the association among serum immunoglobulin G (IgG) responses to Aggregatibacter actinomycetemcomitans (Aa) serotypes a, b and c, Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf) and clinical parameters in Aggressive Periodontitis (AP) subjects. Associations between periodontal pathogens and clinical and immunological parameters were also evaluated. Thirty-eight subjects diagnosed with generalized AP (GAP) and localized AP (LAP) were included. Ten healthy controls were also evaluated. Clinical parameters were assessed and percentages of subgingival levels of Aa, Pg and Tf (beyond bacterial load), were determined by quantitative real-time polymerase chain reaction. Serum IgG antibody levels against Aa, Pg and Tf were evaluated by enzyme-linked immunosorbent assay. Percentages of Aa, Pg and Tf were significantly higher in AP than in controls. The response to Aa serotype c was higher in LAP subjects than in controls. There were no differences in microbial composition or antibodies responses between GAP and LAP, except for IgG response to Tf. Pg levels were correlated with probing depth (PD), BoP and CAL in GAP but not in LAP subjects. Tf levels correlated with PD and CAL in GAP subjects. In GAP, the infection levels of Aa and Pg correlated with the corresponding IgG levels to Aa serotype c and Pg. Given the evidences that IgG response in AP patients correlated with bacterial infection level in GAP, but not in LAP, and that LAP patients lack a response to Tf, despite harbouring this species, our data suggest a difference in host immune defence between these two forms of aggressive periodontitis.

Development of a Taqman real-time PCR assay for detection of Leifsonia xyli subsp xyli

Leifsonia xyli subsp xyli (Lxx) is the etiological agent of ratoon-stunting disease (RSD), one of the most important diseases that affects productivity of sugarcane crops. The lack of defined external symptoms in most plants is a challenge for the diagnosis of RSD facilitating its spread in production fields. In this study a Taqman® real-time polymerase chain reaction (qPCR) assay was developed for detection of the bacteria in different tissues of the plants and compared to conventional PCR and nested-PCR assays. The bacterial DNA was amplified by the nested-PCR and qPCR assays, indicating that conventional PCR lacks sufficient sensitivity to be used as a diagnostic tool for RSD. On the other hand, qPCR is more advantageous than nested-PCR for processing large amounts of samples since it does not need post processing steps for visualization of results and the level of bacterial infection can be quantified. Therefore by improving the diagnosis of RSD in field plants, it can be applied to monitor losses caused by the disease, as a tool to monitor the efficacy of sanitation procedures and in the development of new sanitizers for Lxx.

Vectorial Competence of Larvae and Adults ofAlphitobius diaperinusin the Transmission ofSalmonellaEnteritidis in Poultry

The ingestion of food products originating from poultry infected with Salmonella spp. is one of the major causes of food poisoning in humans. The control of poultry salmonellosis is particularly difficult since birds are asymptomatic and numerous factors may expedite the maintenance of bacteria in poultry production facilities. The aim of the study was to determine the vectorial capacity of adults and larvae of Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the experimental transmission of Salmonella Enteritidis phage type 4 to 1-day-old specific pathogen-free White Leghorn chicks. Adult insects and larvae were starved for 1 day, fed for 24 h or 7 days on sterile ration that had been treated with Salmonella Enteritidis phage type 4, and the levels of bacterial infection were determined. Infected adult insects and larvae were fed to groups of day-old chicks, after which bacteria were recovered from cecum, liver, and spleen samples over a 7-day period. Infected larvae were more efficient than adult insects in transmitting Salmonella Enteritidis to chicks. Higher concentrations of bacteria could be reisolated from the cecum, liver, and spleen of chicks that had ingested infected larvae compared with those that had ingested infected adults. The control of A. diaperinus, and particularly of the larvae, represents a critical factor in the reduction of Salmonella spp. in poultry farms.

Adoptive transfer of CD4 spleen cells isolated from mice immunized with a 125 amino-acid fragment of H. pylori urease B reduces Heucobacter infection in recipient BALB/c mice

Mucosal immunization with a 125 amino-acid fragment of H. pylori urease B (HpUreB220_345) and cholera toxin (CT) is sufficient to prevent Helicobacter infection in BALB/c mice. Aim: To determine whether adoptive transfer of CD4 spleen cells isolated from mice immunized with HpUreB220_345 can confer protection to recipient BALB/c mice against Helicobacter infection. Methods: Donor BALB/c mice were nasally immunized with HpUreB220_345 and CT and infected with H. felis (Hf). CD4 spleen cells were transferred intravenously to recipient BALB/c mice (2xl 06/mouse), either directly or after in vitro stimulation with HpUreB 220_ 345. Recipient and naive mice (lO/group) were infected with Hf one day after transfer and sacrificed 2 weeks later. Infection status was determined by Urease Test (UT). p values were determined by WilcoxonlKruskalWallis test compared to control mice Results: Donor mice were split into protected (9/15) and unprotected animals (6/15) according to their UT (mean O~O and 0.5~0.1, respectively). Injection of CD4 from unprotected donors before Hf infection significantly reduced bacterial colonization compared to control infected mice. Adoptive transfer of CD4 from protected mice had no effect on the level of Hf infection. The difference in the efficacy of CD4 from protected and unprotected donors was significant (p=O.03). After in vitro stimulation with HpUreB220_345' CD4 spleen cells from both unprotected and protected donors decrease the level of bacterial infection in recipient mice Conclusions: Adoptive transfer of CD4 spleen cells from mice immunized with a 125 amino-acid fragment of urease B can decrease the level of Helicobacter infection in recipient mice. The fact that the CD4 cells from protected donor spleens need to be stimulated to exert an effect in recipients suggest that they are in lower number compared to unprotected donors, probably because most of them have already migrated to the stomach

Penetration of host cell lines by bacteria. Characteristics of the process of intracellular bacterial infection.

A model which describes the characteristics of the penetration of the cells by bacteria is presented. Since the process of invasion is preceded necessarily by the step in which the bacteria adhere to the cells, the proposed model is based on the expressions previously derived for the process of adhesion, which allow us to determine the number of attached bacteria under different conditions. Thus, the model considers that invasion occurs irreversibly from attached bacteria to specific receptors located on the cell surface with a rate coefficient = ki so that the invasive capacity in a given bacterium-host cell system is mainly determined by the value of this coefficient. Once internalized, the bacteria can follow three different time courses, namely: 1) intracellular growth is hindered so that the bacteria remain in stationary phase, 2) there is a lag phase during which the bacteria stay in stationary phase before they are able to grow exponentially with a rate coefficient = kc, and 3) the bacteria exhibit a growth exponential phase as they enter the cells. In turn, the time course followed by extracellular bacteria also has a decisive influence on the process of invasion and, in this regard, unbound bacteria are considered either in stationary or in exponential phase. Expressions for these different situations have been derived, and from them, procedures to determine the levels of bacterial infection and for quantitative invasive data analysis are presented.

Effects of Weevil (Coleoptera: Curculionidae) Infestation on Abiotic and Biotic Quality of Stored Wheat

The changes in quality of wheat or wheat plus dockage infested with either the granary weevil, Sitophilus granarius (L.), or the rice weevil, S. oryzae (L.), were determined over 20 weeks at 30°C and 70% RH. The quality evaluation criteria used were the changes in fat acidity values (FAV), seed germination, germ and endosperm damage, and fungal and bacterial infection. Thriving infestations (910–2,011 adults per 138 g wheat) of the two weevil species caused extensive germ and endosperm damage; significant increases in FAV, fungal ( Aspergillus glaucus group species and Penicillium spp.) and bacterial infection levels occurred compared to levels in noninfested wheat or wheat-plus-dockage controls. Sharp increases in moisture content occurred in wheat plus dockage infested with S. oryzae , which multiplied faster than S. granarius .

Effect of Pyralid Moth Infestation on Fat Acidity, Seed Germination, and Microflora of Stored Wheat1

Stored wheat infested by each of two species of stored-product moths, Plodia interpunctella (Hubner) and Ephestia cautella (Walker), at 30° C and 70% RH for 20 weeks was assessed to determine the effects of these insects on the keeping quality of wheat and wheat mixed with dockage. Moth infestation in wheat mixed with dockage resulted in significantly lower fat acidity values than in noninfested wheat and dockage. Wheat in which both species were present and wheat subjected to the dockage treatment had significantly lower seed germination than the control wheat. Insect infestation also led to increases in the level of bacterial infection. P. interpunctella decreased the level of seed infection by fungi of the Aspergillus glaucus group and damaged the endosperm of wheat more than E. cautella. E. cautella decreased Alternaria alternata (Fr.) Keissler infection, whereas both moth species damaged the germ more than the endosperm of the wheat. The presence of these insects did not affect seed moisture content and infection by Penicillium .

Bacterial infection/invasion in fish flesh

SummaryExperiments with mechanical treatment of trout have been carried out to show whether there exists any correlation between the stress of the animal before death and the level of bacterial infection in the flesh and/or the quality of the fish determined by organoleptic assessment.The quality and keeping time of the trout is reduced when the fish is exposed to physical stress. The reduction increases with increasing mechanical treatment and is bigger in feeding than in starving fish.The infection level in the fish muscle increases with increasing physical stress and is higher for feeding than for starving trout.When the count of bacteria is higher than 100/g there is a very good correlation between the log count and the organoleptic score.