Search Results (141)

The rise of multidrug-resistant Pseudomonas aeruginosa underscores the need for novel therapeutic targets beyond conventional peptidoglycan biosynthesis. Some bacterial strains bypass MurA inhibition by fosfomycin via a cell wall salvage pathway. This study targeted P. aeruginosa AmgK (PaAmgK) and MurU (PaMurU) to identify inhibitors that could complement fosfomycin therapy. A malachite-green-based dual-enzyme assay enabled efficient activity measurements and high-throughput chemical screening. Screening 232 compounds identified Congo red and CTAB as potent PaMurU inhibitors. A targeted mass spectrometric analysis confirmed the selective inhibition of PaMurU relative to that of PaAmgK. Molecular docking simulations indicate that Congo red preferentially interacts with PaMurU through electrostatic contacts, primarily involving the residues Arg28 and Arg202. The binding of Congo red to PaMurU was corroborated further using SUPR-differential scanning fluorimetry (SUPR-DSF), which revealed ligand-induced thermal destabilization. Ongoing X-ray crystallographic studies, in conjunction with site-directed mutagenesis and enzyme kinetic analyses, aim to elucidate the binding mode at an atomic resolution. Full article

Background and Objectives: Spontaneous bacterial peritonitis (SBP) is both a prevalent and severe complication among individuals with cirrhosis. This systematic review and meta-analysis was designed to evaluate the diagnostic accuracy of procalcitonin (PCT) and compare it to C-reactive protein (CRP) in cirrhotic patients with suspected SBP. Materials and Methods: We performed an extensive literature review utilizing databases including MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. Original investigations reporting PCT diagnostic accuracy for SBP in cirrhotic populations were included. We computed pooled measures of sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio, and SROC curve area under the curve, with corresponding 95% confidence intervals (CIs). Results: Meta-analytical synthesis encompassed twenty eligible studies. Diagnostic accuracy analysis revealed PCT sensitivity of 0.73 (95% CI, 0.61–0.83) and specificity of 0.88 (95% CI, 0.83–0.91). Likelihood ratio yielded positive values of 6.0 (95% CI, 4.1–8.8) and negative values of 0.30 (95% CI, 0.20–0.47). Overall discriminative ability, quantified through SROC curve analysis, demonstrated an AUC of 0.90 (95% CI, 0.87–0.92). Head-to-head comparisons between PCT and CRP were available from ten studies, demonstrating PCT’s superior diagnostic accuracy over CRP, with significantly higher AUC values (PCT: 0.89, 95% CI 0.86–0.91; CRP: 0.74, 95% CI 0.70–0.78, p < 0.01). Conclusions: Although PCT demonstrates higher diagnostic accuracy than CRP, it does not appear to provide sufficient accuracy to support treatment decisions for SBP. We recommend not relying solely on the PCT test and advise that it be interpreted in conjunction with clinical findings. Full article

Heat shock proteins (HSPs), particularly HSP70, play a vital role in fish immune defense against pathogens. The administration of DnaK (bacterial homolog of HSP70) may be a strategy to potentiate the immune response and survival of aquatic organisms. This study evaluates the effect of cells overexpressing DnaK on mortality and immune-related gene expression in gnotobiotic sea bass larvae challenged with Vibrio anguillarum. Larvae were subjected to different treatments: NB (no bacteria), YS0 (E. coli with no plasmid), YS1 (E. coli expressing truncated DnaK), and YS2 (E. coli expressing DnaK), and then infected with V. anguillarum at 7 days post-hatching (dph). Mortality was monitored, and RT-qPCR was used to evaluate immune gene expression at 0, 18, 24, 36, and 120 hpc. While no significant variations were recorded in the non-challenged larvae, constant and sustained mortality was observed in challenged larvae from 60 to 120 hpc. However, lower mortality was observed in the larvae treated with DnaK. DnaK treatment promoted the expression of antimicrobial (hepcidin, transferrin) and chemotaxis genes (ccl4), which was further enhanced after a challenge with V. anguillarum, in conjunction with the modulation of il1β and il-8 at 120 hpc. These findings suggest that DnaK induces a potent innate immune response, improving survival against V. anguillarum and supporting its potential use as a disease-preventive strategy in aquaculture. Full article

Background: Multi-antibiotic resistance has become an alarming issue in treating bacterial infections in both community and medical environments. Globally, the scientific community has been exploring multi-antibiotic techniques to find new ways to address this challenge. To address this critical challenge and explore alternative antibiotic treatments, we investigated the potential of Solanum trilobatum, an edible and medicinally important herb plant in Ayurvedic medicine. Methods: Our research focused on a 60 kDa serine protease isolated and purified from the leaves of S. trilobatum, which showed evidence of possessing hydrolase activity. In this study, we examined the capability of the purified enzyme to eradicate preformed biofilms of S. aureus in combination with ampicillin. Additionally, we assessed the stability of the enzyme in the presence of metal ions and detergents. Results: Enzyme kinetics revealed a Vmax of 48.63 µM/min and a Km of 14.08 µM, indicating efficient enzymatic activity. Furthermore, the enzyme exhibited maximum activity at physiological pH, suggesting its potential effectiveness under physiological conditions. Conclusions: Our preliminary findings highlight the promising role of this enzyme as a potential agent to combat S. aureus biofilms, especially when used in conjunction with ampicillin, as an alternative antibiotic approach. Full article

Phosphorus is an important macronutrient for plant development, but its bioavailability in soil is often limited. Phosphate-solubilizing microorganisms play a vital role in phosphorus biogeochemistry, offering a sustainable alternative to chemical fertilizers, which pose environmental risks. Manual measurements for quantifying phosphate solubilization capacity are laborious, subjective, and time-consuming, so there is a need to develop more efficient and objective approaches. This study aimed to develop and validate a machine vision system called IGLOO to automate and optimize the determination of relative phosphate solubilization efficiency in phosphate-solubilizing bacteria. IGLOO was developed using YOLOv8 in conjunction with creating and labeling a dataset of images of bacterial colonies grown in vitro with the bacterial strains Enterobacter R11 and FCRK4. The model was trained with a different number of epochs. IGLOO’s performance was evaluated by comparing its segmentation accuracy with accepted metrics in the domain and by contrasting its solubilization efficiency estimates with experts’ manual measurements. The model achieved greater than 90% accuracy for colony and halo detection, with a relative error of less than 6% compared to manual measurements, demonstrating its reliability by minimizing observer variability. Finally, IGLOO represents a significant advance in the quantitative evaluation of phosphate solubilization of microorganisms because it reduces analysis time and provides objective and reproducible results for agricultural studies. Full article

Biofilms are structurally organized communities of microorganisms that adhere to a variety of surfaces. These communities produce protective matrices consisting of polymeric polysaccharides, proteins, nucleic acids, and/or lipids that promote shared resistance to various environmental threats, including chemical, antibiotic, and immune insults. While algal and bacterial biofilms are more apparent in the scientific zeitgeist, many fungal pathogens also form biofilms. These surprisingly common biofilms are morphologically distinct from the multicellular molds and mushrooms normally associated with fungi and are instead an assemblage of single-celled organisms. As a collection of yeast and filamentous cells cloaked in an extracellular matrix, fungal biofilms are an extreme threat to public health, especially in conjunction with surgical implants. The encapsulated yeast, Cryptococcus neoformans, is an opportunistic pathogen that causes both pulmonary and disseminated infections, particularly in immunocompromised individuals. However, there is an emerging trend of cryptococcosis among otherwise healthy individuals. C. neoformans forms biofilms in diverse environments, including within human hosts. Notably, biofilm association correlates with increased expression of multiple virulence factors and increased resistance to both host defenses and antifungal treatments. Thus, it is crucial to develop novel strategies to combat fungal biofilms. In this review, we discuss the development and treatment of fungal biofilms, with a particular focus on C. neoformans. Full article

The etiology and resistance pattern of bacterial conjunctivitis varies depending on the patient’s care setting and age. A retrospective, observational study was conducted in a tertiary care teaching hospital. A total of 126 patients—76 adults and 50 children—diagnosed with conjunctival infection during inpatient or ambulatory care were analyzed. In the samples of adult patients, isolates were represented by Gram-positive cocci (57.7%; Staphylococcus spp., S. pneumoniae) followed by Enterobacterales (17.97%; P. mirabilis, E. coli, Klebsiella spp.), and non-fermenters (7.69%; Pseudomonas spp., A. baumannii). Multidrug-resistant (52.17%) and extensively drug-resistant (21.73%) pathogens (predominantly Gram-negative bacilli) were identified in conjunctival swabs of hospitalized adult patients. The main isolates (55.77%) identified in children’s conjunctival swabs belonged to S. aureus, H. influenzae, and S. pneumoniae, followed by Enterobacterales (19.22%; E. coli, P. mirabilis, M. morganii) and fungi (3.48%). Methicillin-resistant S. aureus (35.71%) and extended-spectrum beta-lactamase-producing K. pneumoniae (8.7%) were identified in the pediatric subgroup of patients. In critically ill adult patients assisted in the intensive care or burn functional units, bacterial conjunctivitis followed the pattern of infections and antimicrobial resistance specific to these categories of patients. In the case of hospitalized children, conjunctivitis was an integral part of the age-related pathology. Full article

In order to investigate the bacterial species present in the conjunctival sacs of dogs with bacterial conjunctivitis in Wuhan (Hongshan District, Wuchang District, Jiangxia District, and Huangpi District) and their resistance to aminoglycoside antibiotics, samples of conjunctival sac secretions were collected from 56 dogs with bacterial conjunctivitis in various regions of Wuhan. Drug susceptibility testing for aminoglycoside antibiotics was performed on the most commonly isolated gram-positive and gram-negative bacteria. The expression of two aminoglycoside modifying enzyme genes, aacA-aphD and aac (6′)-Ib, and three 16S rRNA methyltransferase genes, rmtB, rmtE and npmA, were analyzed by PCR. The results showed that a total of 123 bacterial strains were cultured from 56 conjunctival sac secretion samples, with Staphylococcus being the most commonly isolated species, followed by Escherichia. Among them, 14 strains of Staphylococcus pseudointermedius were not resistant to tobramycin, amikacin, gentamicin or neomycin, but the resistance rates to streptomycin and kanamycin were 35.71% and 42.86%, respectively. Among them, 14 Escherichia coli strains were not resistant to tobramycin and gentamicin, but they showed high resistance rates to neomycin and kanamycin (both at 50%). The detection rate of the aacA-aphD gene in Staphylococcus pseudointermedius strains was 100%. The detection rates of the rmtB gene and rmtE gene in Escherichia coli were 85.71% and 28.57%, respectively, while the aac(6′)-Ib gene and npmA gene were not detected. Full article

Background and aim: Gardenia jasminoides (G. jasminoides) could treat various inflammatory diseases. This study aimed to investigate the effects of G. jasminoides fruit extract on gastric inflammation and protective mechanisms in Helicobacter pylori (H. pylori)-induced gastritis. Experimental procedure: G. jasminoides fruit extract was prepared and analyzed for geniposide content. The inhibitory effect of the extract on H. pylori growth was investigated using the disk diffusion method. The in vitro anti-inflammatory property of the extract was evaluated using the erythrocyte membrane stabilization method. Thirty-five male Sprague–Dawley rats were inoculated with H. pylori (10⁸–10¹⁰ colony-forming unit/mL) and divided into five groups. Each group was treated with various doses of the extract (98–395 mg/kg). The serum and stomach tissue of the rats were evaluated using enzyme-linked immunosorbent assay, histopathology, and immunohistochemistry. Results and conclusions: The geniposide content in the dried extract was 8.12% ± 0.79% by dry weight. The inhibition zone was observed at the extract ≥ 1.97 mg/disk, and the extract presented anti-inflammatory potential. The H. pylori-inoculated rats had a significant increase in serum interleukin (IL)-17, IL-33, and gastric epidermal growth factor (EGF) levels and a significant decrease in serum prostaglandin E₂ level (p < 0.05) in conjunction with the development of gastric inflammation on histopathology. The treatment of the extract could significantly decrease the serum IL-17, IL-33, and gastric EGF levels, significantly increase the serum PGE₂ level (p < 0.05), and improve gastric histopathology. Thus, G. jasminoides fruit extract attenuated H. pylori-induced gastritis by inhibiting bacterial growth, reducing inflammation, and enhancing protective mechanisms. Full article

As sustainable forest management gains increasing attention, comprehending the impact of stand density on soil properties and microbial communities is crucial for optimizing forest ecosystem functions. This study employed high-throughput sequencing in conjunction with soil physicochemical analysis to assess the effects of stand density on soil physicochemical properties and microbial community characteristics in Chinese fir plantations, aiming to elucidate the influence of density regulation on ecosystem services. Our results suggested that changes in soil physicochemical properties and microenvironmental conditions were key drivers of soil microbial diversity. Total carbon (TC), soluble nitrogen (SN), and light fraction organic matter decreased with increasing stand density, while total potassium (TK) and available phosphorus (AP) concentrations increased. The plot with a density of 900 trees ha⁻¹ exhibited the highest bacterial diversity, in contrast to the plot with 1500 trees ha⁻¹, which showed the lowest. The dominant microbial taxa were similar across different stand retention densities, with Acidobacteria, Proteobacteria, and Chloroflexi being the predominant bacterial phyla and Ascomycota and Basidiomycota being the main fungal groups. Significant positive correlations were observed between soil microbial community structures and environmental factors, particularly with respect to soil phosphorus and nitrogen content. The present study demonstrated that reduced stand densities modulated soil nutrient content and enhanced bacterial diversity, thereby contributing to a more complex and stable soil ecosystem structure. These insights provide a scientific foundation for optimizing the management of Chinese fir plantations, thereby supporting the sustainable development of forest ecosystems. Full article

Concrete is prone to cracking over time, leading to the deterioration of concrete structures. Using the biomineralization capabilities of bacteria, cracks in concrete can be remediated in favorable conditions. In this study, Bacillus subtilis spores were immobilized in three different healing agents, namely lightweight expanded clay aggregates (LECAs), polyvinyl acetate (PVA) fibers, and an air-entraining admixture (AEA). Bacillus subtilis spores, with a turbidity equivalent to a 4 McFarland standard, were used in three different dosages, namely 0.01, 0.1, and 1% (by weight) of cement. Based on the dosage, three groups were developed and each group consisted of a total of nine mixes, which were differentiated based on the method of delivery of the bacterial spores. The specimens were pre-cracked after 7 days, using an embedded steel rod, after being post-tensioned in a universal testing machine. The self-healing efficiency of the concrete was evaluated using ultrasonic pulse velocity testing and surface crack analysis, using ImageJ software, and the self-healing precipitate was analyzed using microstructural tests, namely scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis. The results verified that the self-healing efficiency of the concrete improved with the increase in the bacterial dosage and with an increase in the curing time. LECAs proved to be a promising bacterial carrier, by accommodating the spores and nutrient media over a period of 196 days. PVA fibers helped in bridging the cracks and provided nucleation sites for the bacteria, which enhanced the calcite precipitation. Similarly, the AEA also improved crack healing by encapsulating the spores and sealing cracks up to 0.25 mm, when used in conjunction with LECAs. Furthermore, microstructural tests verified the formation of calcite as a healing product within the cracks in the bioconcrete. The results of this study offer valuable insights for the construction industry, highlighting the ability of bacteria to reduce the deterioration of concrete structures and promoting a sustainable approach that minimizes the need for manual repairs, particularly in hard-to-reach areas. Full article

Morchella mushroom is a nutritionally rich and rare edible fungus. The traditional cultivation model, which relies on expanding the cultivation area to meet market demand, is no longer sufficient to address the rapidly growing market demand. Enhancing the yield and quality of Morchella without increasing the cultivation area is an intractable challenge in the development of the Morchella mushroom industry. Against this backdrop, this study investigates the effects of different amounts of wood ash (WA) application on the yield and quality of Morchella, and conducts an in-depth analysis in conjunction with soil physicochemical properties and microbial communities. The results indicate that the application of WA improves both the yield and quality of Morchella, with the highest yield increase observed in the WA2 treatment (4000 kg/hm²), which showed a 118.36% increase compared to the control group (CK). The application of WA also modified the physicochemical properties of the soil, significantly improving the integrated fertility index of the soil (IFI, p < 0.05). The soil microbial community structure was altered by the addition of WA. Redundancy analysis (RDA) revealed that pH and total potassium (TK) were the main environmental factors influencing the bacterial community, while pH, TK, and total nitrogen (TN) were the main factors influencing the fungal community structure. In addition, bacterial community diversity tended to increase with higher WA application rates, whereas fungal community diversity generally showed a decreasing trend. Furthermore, the relative abundance of beneficial microbial communities, such as Acidobacteriota, which promote the growth of Morchella, increased with higher WA application, while the relative abundance of detrimental microbial communities, such as Xanthomonadaceae, decreased. Partial least squares path model (PLS-PM) analysis of external factors affecting Morchella yield and quality indicated that WA application can alter soil physicochemical properties and soil microbial communities, thereby improving Morchella yield and quality. Among these factors, soil fertility was identified as the most important determinant of Morchella yield and quality. Full article

Background/Objectives: In environments with high-frequency contact surfaces, drug-resistant bacteria, such as carbapenem-resistant Enterobacterales and methicillin-resistant Staphylococcus aureus (MRSA), can survive for extended periods, contributing to healthcare-associated infections. Ultraviolet (UV)-C irradiation often fails to adequately disinfect shadowed areas, leading to a persistent contamination risk. We evaluated the effectiveness of using a UV-C containment unit (UVCCU) in conjunction with UV-C irradiation to improve the sterilization effects on both direct and indirect surfaces, including shadowed areas, and to assess the leakage of UV radiation to the surroundings. Methods: In a model patient room, agar media inoculated with carbapenem-resistant Enterobacter cloacae and MRSA were placed at multiple locations on direct and indirect surfaces around the bed. We used the UV-C irradiation system, UVDI-360, to irradiate the bedroom-environment surfaces with and without a UVCCU. The reduction in bacterial colony counts with and without the UVCCU was measured by counting colony-forming units and calculating the log reduction values, and the UV radiation leakage outside the UVCCU was measured. Results: The use of the UVCCU led to a significant reduction in MRSA colony counts, even in shadowed areas that had previously been inadequately disinfected (with the UVCCU: 2.7 [2.7–2.8]; without the UVCCU: 0.6 [0.5–0.7]; p < 0.01). Additionally, the use of the UVCCU kept the UV radiation leakage to the surrounding environment within regulated limits. Conclusions: These findings suggest that a UVCCU can enhance the disinfection efficacy for multidrug-resistant organisms on healthcare environmental surfaces. The portability and ease of use of the UVCCU indicate its promise as an auxiliary device for UV-C disinfection in healthcare settings. Full article

Soil bacterial communities play a crucial role in the functioning of estuarine wetlands. Investigating the structure and function of these communities across various wetland types, along with the key factors influencing them, is essential for understanding the relationship between bacteria and wetland ecosystems. The Liaohe Estuary Wetland formed this study’s research area, and soil samples from four distinct wetland types were utilized: suaeda wetlands, reed wetlands, pond returning wetlands, and tidal flat wetlands. The structure and function of the soil bacterial communities were examined using Illumina MiSeq high-throughput sequencing technology in conjunction with the PICRUSt analysis method. The results indicate that different wetland types significantly affect the physical and chemical properties of soil, as well as the structure and function of bacterial communities. The abundance and diversity of soil bacterial communities were highest in the suaeda wetland and lowest in the tidal flat wetland. The dominant bacterial phyla identified were Proteobacteria and Bacteroidota. Furthermore, the dominant bacterial genera identified included RSA9, SZUA_442, and SP4260. The primary functional pathways associated with the bacterial communities involved the biosynthesis of valine, leucine, and isoleucine, as well as lipoic acid metabolism, which are crucial for the carbon and nitrogen cycles. This study enhances our understanding of the mutual feedback between river estuary wetland ecosystems and environmental changes, providing a theoretical foundation for the protection and management of wetlands. Full article

Background and Objectives: Sepsis, a leading global health challenge, accounts for around 20% of deaths worldwide. The complexity of sepsis, especially the difference between bacterial and viral etiologies, requires an effective assessment of microcirculation during resuscitation. This study aimed to evaluate the impact of infusion therapy on microcirculation in patients with sepsis, focusing on bacterial- and COVID-19-associated sepsis using remote photoplethysmography (rPPG) and the automated capillary refill time (aCRT). Materials and Methods: This single-center prospective study was conducted in the ICU of Pauls Stradins Clinical University Hospital, including 20 patients with sepsis/septic shock. The patients were selected based on hemodynamic instability and divided into COVID-19 and Bacterial Septic Shock groups. Fluid responsiveness was assessed using the Passive Leg Raising Test (PLRT). Systemic hemodynamics and microcirculation were monitored through MAP CRT, rPPG, and serum lactate levels. Statistical analyses compared responses within and between the groups across different stages of the protocol. Results: The Bacterial group exhibited higher initial serum lactate levels and more pronounced microcirculatory dysfunction than the COVID-19 group. rPPG was more sensitive in detecting perfusion changes, showing significant differences between the groups. The automated CRT demonstrated greater sensitivity compared to the manual CRT, revealing significant differences during PLRT stages between bacterial- and COVID-19-associated sepsis. Both groups had a transient hemodynamic response to PLRT, with subsequent stabilization upon fluid infusion. Conclusions: When managing patients with sepsis in intensive care, monitoring microcirculation is of paramount importance in infusion therapy. Our study highlights the potential of rPPG and aCRT as tools for this purpose. These techniques can be used in conjunction with routine parameters, such as lactate levels and systemic hemodynamic parameters, to provide a comprehensive assessment of a patient’s condition. Full article