CHARACTERISTICS OF VIRAL ANTIGENS AND MICROBIAL SPECTRUM OF UPPER AND LOWER RESPIRATORY TRACT IN INFANTS WITH BRONCHITIS

Introduction. The difficulty in diagnosing different clinical forms of bronchitis is due to the fact that their clinical manifestations have a number of similar symptoms, despite the fact that these diseases may be as-sociated with different forms according to the classification. Diagnosis can be often complicated by the pre-disposition of very young children to recurrent respiratory diseases, which often mark the formation of a pro-longed and recurrent course of the disease caused by viral and bacterial contamination of the respiratory tract. The aim of this study is to investigate viral and microbial contamination of the respiratory tract in vari-ous clinical forms of bronchitis of infants and to clarify their etiological significance in parallel with the as-sessment of the intestinal microflora. Materials and methods. 578 children aged from 6 months to 3 years with various clinical forms of bronchitis were monitored. Virological examination was performed by the direct Coons method, which detected viral antigens in the cells of the mucous membrane of the lower nasal si-nuses. Bacteriological examination was performed by bacterial inoculation of nasopharyngeal mucus, spu-tum and feces in a nutrient medium. Results. Clinical and laboratory examination of young infants made it possible to identify the influence of detected viral antigens and pathogenic microflora in the throat, sputum and feces on the formation of various clinical forms of bronchitis and their clinical peculiarities not only in the period of exacerbation, but also in a remission period that indicates the persistence of viruses and bacteria. Conclusion. Detection of viral antigens, dysbiosis and microbial aggression of the upper and lower respira-tory tract gives grounds for substantiating the indications for staged rehabilitation therapy for infants with various clinical forms of bronchitis.

In Vitro screening of ammonia and nitrite-degrading bacteria isolated from broiler chicken (Gallus gallus domesticus) intestines and pond sediment of nile tilapia (Oreochromis niloticus): A preliminary study

The high level of ammonia and nitrite is a toxic factor for both poultry and aquaculture animals that directly lead to lower economic benefits. Thus, reducing ammonia and nitrite levels is an essential key for successful culture and is also important to reduce the amount of ammonia and nitrite released into the environment. This study aimed to screen bacteria having a capacity to degrade either ammonia or nitrite in vitro. Five bacterial strains previously isolated from broiler chicken (Gallus gallus domesticus) intestine and pond sediment of Nile Nilapia (Oreochromis niloticus) were used in this study, namely IBP-1, IBP-2, IBP-3, IBP-4, and IBP-5 strains. The screenings were performed using either NH4Cl containing medium or NaNO2 containing medium to determine the ability of bacteria to reduce ammonia or nitrite respectively. The ammonia and nitrite levels were afterwards measured at the beginning (day 0: before bacterial inoculation), 24h (day 1), 48h (day 2), and 72h (day 3) after the addition of 1 ml of the bacterial suspension. The results showed that the five bacterial isolates were able to degrade the ammonia and nitrite content. The greatest reduction of ammonia was achieved by IBP-4 strain (0.00 mg/l), followed by IBP-5 strain (0.04 mg/l), IBP-1 strain (0.05 mg/l), IBP-3 strain (0.14 mg/l) and IBP-2 strain (0.19 mg/l). IBP-1 and IBP-2 strains showed the highest reduction of nitrite levels with values of 0.01 mg/l and 0.02 mg/l after 72h of bacterial inoculation. These results suggest that the five bacterial strains are potentially used for degrading toxic ammonia and nitrite.

A non-bactericidal cathelicidin provides prophylactic efficacy against bacterial infection by driving phagocyte influx

The roles of bactericidal cathelicidins against bacterial infection have been extensively studied. However, the anti-bacterial property and mechanism of action of non-bactericidal cathelicidins are rarely known. Herein, a novel naturally occurring cathelicidin (PopuCATH) from tree frog (Polypedates puerensis) didn’t show any direct anti-bacterial activity in vitro. Intriguingly, intraperitoneal injection of PopuCATH before bacterial inoculation significantly reduced the bacterial load in tree frogs and mice, and reduced the inflammatory response induced by bacterial inoculation in mice. PopuCATH pretreatment also increased the survival rates of septic mice induced by a lethal dose of bacterial inoculation or cecal ligation and puncture (CLP). Intraperitoneal injection of PopuCATH significantly drove the leukocyte influx in both frogs and mice. In mice, PopuCATH rapidly drove neutrophil, monocyte/macrophage influx in mouse abdominal cavity and peripheral blood with a negligible impact on T and B lymphocytes, and neutrophils, monocytes/macrophages, but not T and B lymphocytes, were required for the preventive efficacy of PopuCATH. PopuCATH did not directly act as chemoattractant for phagocytes, but PopuCATH obviously drove phagocyte migration when it was cultured with macrophages. PopuCATH significantly elicited chemokine/cytokine production in macrophages through activating p38/ERK mitogen-activated protein kinases (MAPKs) and NF-κB p65. PopuCATH markedly enhanced neutrophil phagocytosis via promoting the release of neutrophil extracellular traps (NETs). Additionally, PopuCATH showed low side effects both in vitro and in vivo. Collectively, PopuCATH acts as a host-based immune defense regulator that provides prophylactic efficacy against bacterial infection without direct antimicrobial effects. Our findings reveal a non-bactericidal cathelicidin which possesses unique anti-bacterial action, and highlight the potential of PopuCATH to prevent bacterial infection.

Can Bacterial Endophytes Be Used as a Promising Bio-Inoculant for the Mitigation of Salinity Stress in Crop Plants?—A Global Meta-Analysis of the Last Decade (2011–2020)

Soil salinity is a major problem affecting crop production worldwide. Lately, there have been great research efforts in increasing the salt tolerance of plants through the inoculation of plant growth-promoting endophytic bacteria. However, their ability to promote plant growth under no-stress and salinity-stress conditions remains largely uncertain. Here, we carried out a global meta-analysis to quantify the plant growth-promoting effects (improvement of morphological attributes, photosynthetic capacity, antioxidative ability, and ion homeostasis) of endophytic bacteria in plants under no-stress and salinity-stress conditions. In addition, we elucidated the underlying mechanisms of growth promotion in salt-sensitive (SS) and salt-tolerant (ST) plants derived from the interaction with endophytic bacteria under no-stress and salinity-stress conditions. Specifically, this work encompassed 42 peer-reviewed articles, a total of 77 experiments, and 24 different bacterial genera. On average, endophytic bacterial inoculation increased morphological parameters. Moreover, the effect of endophytic bacteria on the total dry biomass, number of leaves, root length, shoot length, and germination rate was generally greater under salinity-stress conditions than no-stress conditions. On a physiological level, the relative better performance of the bacterial inoculants under the salinity-stress condition was associated with the increase in total chlorophyll and chlorophyll-b, as well as with the decrease of 1-aminocylopropane-1-carboxylate concentration. Moreover, under the salinity-stress condition, bacterial inoculation conferred a significantly higher increase in root K+ concentration and decrease in leaf Na+ concentration than under the no-stress condition. In SS plants, bacterial inoculation induced a higher increase in chlorophyll-b and superoxide dismutase activity, as well as a higher decrease in abscisic acid content, than in ST plants. Under salinity-stress, endophytic bacterial inoculation increased root K+ concentration in both SS and ST plants but decreased root Na+ concentration only in ST plants. Overall, this meta-analysis suggests that endophytic bacterial inoculation is beneficial under both no salinity-stress and salinity-stress conditions, but the magnitude of benefit is definitely higher under salinity-stress conditions and varies with the salt tolerance level of plants.

Can Inoculation With the Bacterial Biostimulant Enterobacter sp. Strain 15S Be an Approach for the Smarter P Fertilization of Maize and Cucumber Plants?

Phosphorus (P) is an essential nutrient for plants. The use of plant growth-promoting bacteria (PGPB) may also improve plant development and enhance nutrient availability, thus providing a promising alternative or supplement to chemical fertilizers. This study aimed to evaluate the effectiveness of Enterobacter sp. strain 15S in improving the growth and P acquisition of maize (monocot) and cucumber (dicot) plants under P-deficient hydroponic conditions, either by itself or by solubilizing an external source of inorganic phosphate (Pi) [Ca3(PO4)2]. The inoculation with Enterobacter 15S elicited different effects on the root architecture and biomass of cucumber and maize depending on the P supply. Under sufficient P, the bacterium induced a positive effect on the whole root system architecture of both plants. However, under P deficiency, the bacterium in combination with Ca3(PO4)2 induced a more remarkable effect on cucumber, while the bacterium alone was better in improving the root system of maize compared to non-inoculated plants. In P-deficient plants, bacterial inoculation also led to a chlorophyll content [soil-plant analysis development (SPAD) index] like that in P-sufficient plants (p < 0.05). Regarding P nutrition, the ionomic analysis indicated that inoculation with Enterobacter 15S increased the allocation of P in roots (+31%) and shoots (+53%) of cucumber plants grown in a P-free nutrient solution (NS) supplemented with the external insoluble phosphate, whereas maize plants inoculated with the bacterium alone showed a higher content of P only in roots (36%) but not in shoots. Furthermore, in P-deficient cucumber plants, all Pi transporter genes (CsPT1.3, CsPT1.4, CsPT1.9, and Cucsa383630.1) were upregulated by the bacterium inoculation, whereas, in P-deficient maize plants, the expression of ZmPT1 and ZmPT5 was downregulated by the bacterial inoculation. Taken together, these results suggest that, in its interaction with P-deficient cucumber plants, Enterobacter strain 15S might have solubilized the Ca3(PO4)2 to help the plants overcome P deficiency, while the association of maize plants with the bacterium might have triggered a different mechanism affecting plant metabolism. Thus, the mechanisms by which Enterobacter 15S improves plant growth and P nutrition are dependent on crop and nutrient status.