Search Results (349)

Background/Objectives: Non-fermenting Gram-negative bacilli (NFGNB) represent a significant clinical challenge due to their intrinsic and acquired resistance, particularly in immunocompromised patients. Infections cause by NFGNB are associated with high morbidity and mortality, especially among patients with cystic fibrosis and hematologic malignancies. This study aimed to assess the in vitro susceptibility of clinically relevant NFGNB isolates to two newer antibiotics, cefiderocol and aztreonam/avibactam, and an established antibiotic, trimethoprim/sulfamethoxazole. Methods: This retrospective, monocentric study analysed 94 NFGNB isolates (30 Pseudomonas aeruginosa, 30 Acinetobacter sp., 24 Stenotrophomonas maltophilia, and 10 Burkholderia cepacia complex). Susceptibility testing for cefiderocol, aztreonam/avibactam, and trimethoprim/sulfamethoxazole was conducted using gradient strip method. MIC values were interpreted using EUCAST breakpoints, ECOFFs, or alternative criteria when necessary. Results: All S. maltophilia isolates were susceptible to cefiderocol (FCR) and aztreonam/avibactam (A/A) based on ECOFFs, with one strain resistant to trimethoprim–sulfamethoxazole (COT). Burkholderia cepacia complex strains also showed high susceptibility to FCR, with only one isolate exceeding the ECOFF for A/A, and 20% resistant to COT. All Acinetobacter sp. isolates were susceptible to FCR; however, most MIC values clustered at or just below the ECOFF value. In P. aeruginosa, one isolate was resistant to FCR, and three isolates (10%) were resistant to A/A. Interestingly, confirmed carbapenemase producers remained susceptible to both FCR and A/A. Most A/A MIC values for P. aeruginosa were just below the ECOFF. Conclusions: Cefiderocol and aztreonam/avibactam demonstrated promising in vitro activity against clinically relevant NFGNB, including carbapenem-resistant strains. These findings support their potential role as therapeutic options for difficult-to-treat infections, particularly in immunocompromised patients. Full article

Previous studies of direct-fed microbial (DFM) supplements showed variable effects on the microbiota and physiology of dairy cows. The main aims of this study were to investigate the milk microbiota of cows supplemented with a lactobacilli-based DFM compared to untreated cows; describe the changes; and quantify the association between the taxa and cow productivity. The study followed seventy-five Holstein–Friesian dairy cows supplemented with a DFM over 16 months compared to seventy-five non-supplemented cows. Twenty-five cows from each group were sampled for microbiota analysis. The top taxa significantly associated with the variables were as follows: Age (Mammaliicoccus_319276, Turicibacter), milk production (Turicibacter, Bifidobacterium_388775), DIM (Stenotrophomonas_A_615274, Pedobacter_887417), milk fat percentage (Pseudomonas_E_647464, Lactobacillus), calendar month (Jeotgalicoccus_A_310962, Planococcus), milk protein percentage (Tistrella, Pseudomonas_E_650325), experimental group (Enterococcus_B, Aeromonas), SCC (Paenochrobactrum, Pseudochrobactrum), and trimester of pregnancy (Dyadobacter_906144, VFJN01 (Acidimicrobiales)). These were identified using multivariable analysis. Twenty-six genera were associated with the differences between experimental groups, including Pseudomonas, Lactococcus and Staphylococcus. Microbial taxa that changed in relative abundance over time included Atopostipes, Brevibacterium and Succinivibrio. Many of these genera were also part of the core microbiota. Supplementation with the DFM significantly altered the milk microbiota composition in the dairy cows, highlighting the impact of long-term DFM supplementation on microbial communities. Full article

The use of postbiotics for dietary fortification in aquaculture is gaining increasing attention due to their potential immunomodulatory and gut health benefits. In this study, we evaluated the effects of postbiotics derived from Vibrio proteolyticus DCF12.2 on intestinal histology, microbiota composition, and the expression of genes related to epithelial integrity and inflammation in juvenile gilthead seabream (Sparus aurata). Fish were fed either a control (CRTL) diet or the postbiotic-supplemented diet (VP) for 62 days. At the end of the feeding trial, a lipopolysaccharide (LPS) challenge was conducted to evaluate the immune response in fish. Histological analysis revealed a healthy mucosa in both groups, though fish fed the VP diet reduced fold height and mucosal layer thickness, alongside a significant increase in goblet cells. Microbiota profiling indicated higher alpha diversity and significant shifts in community composition in the VP group, including enrichment of potentially beneficial genera (Pseudomonas, Sphingomonas) and depletion of opportunistic taxa (Enterococcus, Stenotrophomonas). After the feeding trial, fish fed the VP diet exhibited downregulation of pro-inflammatory markers (tnfα, cox2). Following LPS challenge, cdh1—a key epithelial adhesion protein required for maintaining intestinal barrier integrity—expression was upregulated significantly in the VP group, suggesting enhanced epithelial resilience. These findings demonstrate that dietary fortification with V. proteolyticus-derived postbiotics supports mucosal health as well as modulates the intestinal microbiota and immune responses in gilthead seabream juveniles, offering a promising strategy for functional aquafeed development in sustainable aquaculture. Full article

Background/Objectives: The present study was aimed at documenting S. maltophilia occurrence in dogs with skin ailments, investigating its virulence, biofilm-forming ability, antimicrobial susceptibility, and zoonotic potential to inform preventive and therapeutic strategies against multidrug resistant S. maltophilia infections. Methods: Skin swabs (n = 300) were collected from dogs with dermatological ailments. Isolation was performed using selective media and confirmed with molecular methods, validated by MALDI Biotyper. Antimicrobial susceptibility testing and efflux activity assessment were conducted. Resistance genes related to sulfonamides, quinolones, and β-lactams were screened. Virulence was assessed by biofilm formation, motility, and virulence gene profiling. Results: In total, 15 S. maltophilia (5%) isolates were identified. All 15 isolates were susceptible to trimethoprim-sulfamethoxazole, enrofloxacin, gatifloxacin, levofloxacin, minocycline, and tigecycline, but resistant to cefpodoxime and aztreonam. The following resistance genes qnr (93.3%), bla_OXA-48 (46.7%), bla_KPC (33.3%), bla_NDM (33.3%), bla_CTX-M (20%), bla_SHV (20%), and bla_TEM (6.7%) were detected. All 15 isolates displayed high efflux activity. Overall, 9 isolates (60%) were strong biofilm producers, and 6 (40%) were moderate. Virulence genes such as virB, motA, rmlA, and fliC were present in all 15 isolates, with others varying in frequency. All isolates exhibited swimming motility. Heat map clustering showed diverse profiles, with no identical isolate patterns. Correlation analysis indicated positive associations between several antimicrobial resistance and virulence genes. Conclusions: This study underscores the zoonotic potential of S. maltophilia from dogs, advocating for a One Health approach to mitigate infection risks and limit the spread of virulent multidrug resistant pathogens. Full article

Crossbreeding often results in heterosis. In this study, we generated hybrids from largemouth bass from geographically isolated populations. Growth, digestive enzyme activity, and muscle nutrient composition were compared between the hybrid groups (NC and CN) and the purebred groups (NN and CC), and the gut microbiota was investigated. The heterosis rates of body length, body height, and body thickness in hybrid largemouth bass were statistically significant. Digestive enzyme activity was higher in the hybrid groups than in the purebred groups. Compared with the CN and CC groups, the NC group had significantly higher levels of essential amino acids and total amino acids in the muscle. The polyunsaturated fatty acid content was lower in the hybrid groups than in the purebred groups. The gut microbiota in the hybrid groups predominantly exhibited a non-additive inheritance pattern, characterized by a reduced abundance of Proteobacteria and an increased abundance of Fusobacteria. Microbial taxa showing differences in abundance between the hybrid and purebred groups harbored genes enriched in multiple amino acid and fatty acid metabolism pathways. Cetobacterium, Pseudomonas, and Stenotrophomonas were more abundant in the hybrids, and were positively correlated with multiple amino acids and fatty acids. These results highlight the critical role of gut microbiota in heterosis. Full article

Maize (Zea mays L.) relies heavily on nitrogen and phosphorus inputs, typically supplied through organic and inorganic fertilizers. However, excessive agrochemical use threatens soil fertility and environmental health. Sustainable alternatives, such as poultry manure (PM) and plant growth-promoting rhizobacteria (PGPR), offer promising solutions. This study examines the effects of a phytobiotic bacterial formulation (PHY), composed of Bacillus subtilis and Microbacterium sp., applied alone and in combination with PM, on maize’s rhizosphere bacteriobiome across key growth stages. Field trials included four treatments: a control, PHY-coated seeds, PM, and combined PHY_PM. The results show that early in development, the PM-treated rhizospheres increased the abundance of beneficial genera such as Sphingomonas, Microvirga, and Streptomyces, though levels declined in later stages. The PHY_PM-treated roots in the seedling phase showed a reduced abundance of taxa like Chryseobacterium, Pedobacter, Phyllobacterium, Sphingobacterium, and Stenotrophomonas, but this effect did not persist. In the PM-treated roots, Flavisolibacter was significantly enriched at harvesting. Overall, beneficial bacteria improved microbial evenness, and the PHY_PM treatment promoted bacterial diversity and maize growth. A genome analysis of the PHY strains revealed plant-beneficial traits, including nutrient mobilization, stress resilience, and biocontrol potential. This study highlights the complementarity of PM and PGPR, showing how their integration reshapes bacteriobiome and correlates with plant parameters in sustainable agriculture. Full article

Background: Intra-abdominal infections (IAIs) caused by Stenotrophomonas maltophilia have rarely been reported. This study aimed to describe the clinical characteristics and risk factors for mortality among patients with S. maltophilia IAIs. Methods: A retrospective study was conducted on inpatients with IAIs caused by S. maltophilia at Tri Service General Hospital from 2004 to 2017. Clinical and microbiologic data of the included cases were reviewed via medical charts and microbiology databases. Multivariable logistic regression analyses were performed to identify risk factors for in-hospital death. Results: In total, 110 patients were diagnosed with S. maltophilia IAIs. Malignancy (56.3%) and liver cirrhosis (35.3%) were the most commonly identified underlying diseases. The major causes of S. maltophilia IAIs were biliary tract infection (42.7%), recent abdominal surgery (35.4%), and spontaneous bacterial peritonitis (20.0%). Polymicrobial infections were observed in 84 (76.4%) patients. In addition to S. maltophilia, co-cultured bacteria (n = 140) included Enterobacterales, representing 19.3% (27/140) of the total isolates, and non-fermentative aerobes, comprising 29.3% (41/140). In addition, anaerobic bacteria and fungi accounted for 9.2% (13/140) and 10% (14/140), respectively. The overall mortality rate was 40.9%. Multivariable logistic regression analysis revealed that high Sequential Organ Failure Assessment scores and malignancies were independent risk factors for mortality, while the immediate administration of appropriate antibiotics targeting S. maltophilia was a protective factor (p < 0.05). Conclusions: Patients with an underlying malignancy or liver cirrhosis were at risk for IAIs caused by S. maltophilia. The prompt initiation of effective antibiotics against S. maltophilia is critical for achieving favorable outcomes. Full article

Background: Stenotrophomonas maltophilia is one of the common causative agents of hospital-acquired infections worldwide. The major concern regarding S. maltophilia infections is its extreme resistance to multiple antibiotics. Methods: Enrofloxacin-resistant mutants of S. maltophilia K279a were selected using a serial passage technique. Results: In this study, we showed that one of the mutant strains, KE507, which was selected from S. maltophilia K279a for its resistance to the veterinary drug enrofloxacin, conferred resistance to trimethoprim/sulfamethoxazole (co-trimoxazole), levofloxacin, and minocycline as per the Clinical and Laboratory Standards Institute guideline. These antibiotics are the first-line drugs routinely used to treat S. maltophilia infections. The KE507 mutant also showed increased resistance to all tested quinolones, azithromycin, and neomycin. Molecular characterization using whole genome sequencing, antibiotic resistance gene expression profiles, and mutational analysis indicated that inactivation of SmeRv (Q208insHSPRFTW), a transcriptional regulator of the SmeVWX multidrug efflux pump, contributes to resistance to quinolones (including levofloxacin), co-trimoxazole, and partially to neomycin, but not to azithromycin or minocycline. These data, together with in silico structural analysis, suggest that the mutation of SmeRv causes a conformational change in the SmeRv structure, which leads to the activation of SmeVWX efflux transporter expression and subsequent resistance to co-trimoxazole and quinolone antibiotics. Conclusion:S. maltophilia can thus acquire resistance to the antibiotics primarily used to treat S. maltophilia infections through the mutation of SmeRv. Full article

Excessive nitrogen fertilizer use has resulted in growing nitrate contamination of groundwater. In this study, an in situ bioelectrochemical reactor (isBER) reinforced with woodchips was developed for the treatment of actual nitrate-contaminated groundwater. During the 75-day experiment, the denitrification performance, grid permeability, and microbial community structure were investigated under different flow rates and current densities. The reactor achieved a remarkable nitrate removal efficiency of 97.6% ± 0.4% and a rate of 2.09 ± 0.14 mg-N/(L·h). These results were obtained at a temperature of 18.5 ± 0.8 °C, a current density of 350 mA/m², and a flow rate of 10 cm/d. Notably, the reactor can adapt to a wide flow-rate range of 5~20 cm/d and the operation proceeded smoothly without any blockages. Furthermore, the cathode module demonstrated enrichment of hydrogen autotrophic denitrifying bacteria (Pseudomonas, Stenotrophomonas) and heterotrophic denitrifying bacteria (Brucella, Enterobacteriaceae). Conversely, the anode module exhibited relatively high enrichment levels of aerobic microorganisms and lignin-degrading bacteria (Cellvibrio). The research results can provide novel insights and technical support for in situ remediation of groundwater nitrate contamination. Full article

Kazakhstan’s rich biodiversity includes diverse apple populations, notably the wild apple tree (Malus sieversii) prized for traits like disease resistance and adaptability, potentially aiding breeding programs. Analyzing their microbiomes offers insights into bacterial diversity and how it influences apple tree development, making it a reliable method for understanding ecological interactions. In this research, 334 apple tree samples were collected from different mountain ranges in southeastern Kazakhstan. An analysis using nanopore-based 16S rRNA sequencing showed a distinct similarity in the microbiome compositions of samples from the Zhongar and Ile Alatau mountain ranges, with a predominance of Pseudomonadaceae, Enterobacteriaceae, and Microbacteriaceae. In contrast, samples from Ketmen ridge showed a higher prevalence of Enterobacteriaceae. Alongside the less represented Pseudomonadaceae family, in the Ketmen ridge region, bacteria of the Xanthomonadaceae, Alcaligenaceae, and Brucellaceae families were also present. Across all regions, beneficial plant-associated bacteria were identified, such as Pseudomonas veronii, Stenotrophomonas geniculata, and Kocuria rhizophila, potentially enhancing plant resilience. However, opportunistic phytopathogens were also detected, including Pseudomonas viridiflava and Serratia marcescens, particularly in the Ile Alatau region. These findings highlight the complex microbial interactions in M. sieversii, thus offering key insights into host—microbe relationships that can inform apple breeding and ecological preservation efforts. Full article

The green synthesis of metal nanoparticles, mediated by extracts from various biological sources, leads to the formation of nanoparticles with unique characteristics and potential biomedical applications. In this study, a fraction of the mucus from the snail Cornu aspersum with MW > 20 kDa was used as a bioreducing and biostabilizing agent to obtain silver nanoparticles (AgNPs) in different pH media (pH 1.5, 3.5, and 7.0). The AgNPs were characterized using UV-visible spectroscopy, SEM, TEM, XRD, and FTIR. The synthesis at pH 1.5 and pH 3.5 in the presence of two reducing agents (i.e., the C. aspersum mucus fraction with MW > 20 kDa and ascorbic acid [AsA]) resulted in the formation of well-formed spherical nanoparticles (NPs) with larger sizes (20–80 nm) than the NPs obtained at pH 7.0 (20–60 nm) in the presence of only one reducing agent. Furthermore, the biosynthesized AgNPs significantly inhibited the growth of medically significant pathogens such as Gram-positive (Bacillus subtilis NBIMCC2353, Bacillus spizizenii ATCC 6633, Staphylococcus aureus ATCC 6538, and Listeria innocua NBIMCC8755) and Gram-negative (Escherichia coli ATCC8739, Salmonella enteitidis NBIMCC8691, Salmonella typhimurium ATCC 14028, Stenotrophomonas maltophilia ATCC 17666) bacteria compared to output mucus. Full article

Background/Objectives: The evidence regarding the efficacy of probiotics in chronic rhinosinusitis (CRS) is very limited, prompting the EPOS2020 steering group to advise against their use in CRS treatment. Therefore, further research to evaluate the impact of probiotics on microbial communities is particularly important. This study aimed to assess the influence of probiotic nasal rinses on nasal microbiota profiles in patients with primary CRS, granulomatosis with polyangiitis (GPA), and nasal septal perforation (NSP) using 16S rRNA sequencing. Methods: Thirty-six patients with nasal mucosal diseases, including sixteen with primary CRS, eleven with GPA, and nine with NSP, were randomly assigned to either a study group receiving nasal rinses with probiotics containing Lactobacillus plantarum and Bifidobacterium animalis, or a control group using nasal rinses with saline. Metagenomic analysis targeting the V3–V4 hypervariable region of the 16S rRNA gene was performed to characterize bacterial and archaeal populations. Results: At the genus level, the most abundant co-colonizers included Staphylococcus, Streptococcus, and Haemophilus. After one month of probiotic rinsing, a decrease in abundance of the genera Finegoldia (p = 0.010), Haemophilus (p = 0.020), Streptococcus (p = 0.027), Staphylococcus (p = 0.033), Micrococcus (p = 0.035), Corynebacterium (p = 0.049), Gemella (p = 0.055), Rubrobacter (p = 0.055), and Pseudonocardia (p = 0.058) was observed. Conversely, the abundance of probiotic species Lactobacillus plantarum and Bifidobacterium animalis increased. Moreover, increases in the genera Dolosigranulum and Stenotrophomonas were observed, although they did not reach statistical significance. Conclusions: Probiotic nasal rinses may contribute to restoring microbial homeostasis by reducing genera associated with inflammatory dysbiosis in nasal inflammatory diseases, warranting further research on their clinical benefits. Full article

Background/Objectives: The increasing threat of antibiotic resistance and the declining efficiency of traditional drug discovery pipelines highlight the urgent need for novel drug targets and effective enzyme inhibitors against infectious diseases. Oligopeptidase B (OPB), a serine protease with trypsin-like specificity that processes low-molecular-weight peptides and oligopeptides, is present in bacteria and certain parasites but absent in mammals. This unique distribution makes OPB an attractive and selective target for antimicrobial drug development. Methods: Three-dimensional models of OPB from Serratia marcescens and Stenotrophomonas maltophilia, previously identified by our research group, were constructed via homology modeling using the best available OPB template from the RCSB Protein Data Bank. The S. marcescens OPB model was subjected to high-throughput virtual screening (HTVS) against the Natural Products Atlas (npatlas) database. Top-ranking compounds were further evaluated using Glide standard precision (SP) and extra precision (XP) docking protocols. Binding affinities were refined using molecular mechanics with generalized born and surface area (MM–GBSA) calculations. Molecular dynamics (MD) simulations assessed binding stability, while absorption distribution metabolism excretion and toxicity (ADMET) profiling evaluated drug-likeness and pharmacokinetic properties. Results: Ten natural product compounds demonstrated stronger binding affinities than antipain, a well-known oligopeptide-based protease inhibitor, as indicated by their more favorable MM–GBSA scores of −60.90 kcal/mol (S. marcescens) and −27.07 kcal/mol (S. maltophilia). Among these, dichrysobactin and validamycin E consistently exhibited favorable binding profiles across both OPB models. MD simulations confirmed the stability of their interactions with OPB active sites, maintaining favorable binding conformations throughout the simulation period. ADMET analysis suggested that while both compounds show promise, lead optimization is required to enhance their drug-like characteristics. Conclusions: This study identifies dichrysobactin and validamycin E as promising OPB inhibitors with potential antimicrobial activity. These findings support their further development as selective and potent agents against bacterial pathogens, including resistant strains, and underscore the need for experimental validation to confirm their efficacy and safety. Full article

Background: Active nasal surveillance culture (ANSC) is recognized to enable rapid detection of antibiotic-resistant bacteria in the intensive care unit (ICU), which can contribute to the prevention of Ventilator-associated pneumonia (VAP). This study aims to evaluate the usefulness of ANSC in assessing the development of VAP in ICU patients. Methods: Patients admitted to the Yamagata Prefectural Central Hospital ICU from January 2017 to 2018 (Term 1) or January 2020 to December 2021 (Term 2) and underwent invasive mechanical ventilation supports were eligible for this study. Nasal swab samples were collected from the patients upon their admission to the ICU. The diagnosis of VAP was made according to the criteria set by the Centers for Disease Control and Prevention. Results: A total of 467 patients (156 women) in term 1, and 312 patients (113 women) in term 2 were enrolled. The incidence of VAP in term 2 was higher than in term 1 (7.1% vs. 12.8%, respectively). ANSC isolated several causative pathogens from the patients on admission who later developed VAP. Haemophilus influenza, Streptococcus pneumoniae, Stenotrophomonas maltophilia, and Pseudomonas aeruginosa had a 100% match rate with the sputum culture, indicating a perfect relation between ANSC results and sputum culture in VAP (+) cases. Conclusions: The isolation of high-risk bacterial species by ANSC could foresee the development of VAP in ICU patients and efficiently prevent VAP in critically ill patients. Full article

Dump sites harbour microorganisms with potential for environmentally friendly industrial applications. This study assessed the lipolytic activity of municipal dumpsite-associated bacteria and evaluated the stability of the most potent isolate’s lipolytic enzyme against laundry detergents. It also examined the crude lipase’s ability to remove stains from cotton fabric. Among twelve bacteria isolated, five demonstrated notable halo zones on tributyrin agar plates. The diameters (mm) were MN38 (11 ± 1.4), MN1310 (8.5 ± 0.7), MN28 (6.5 ± 0.71), MN18 (7.0 ± 1.4), and MN310 (8.15 ± 0.21). Quantitative analysis revealed that MN38 exhibited the highest lipase activity (14.76 ± 0.27 U/mL), while MN1310 showed the lowest (6.40 ± 0.85 U/mL). Nucleotide sequence analysis identified the isolates as Raoultella terrigena veli18 (MN38), Stenotrophomonas maltophilia veli96 (MN1310), Viridibacillus sp. veli10 (MN28), Stenotrophomonas sp. veli19 (MN18), and Klebsiella sp. veli70 (MN310). The crude lipase from R. terrigena veli18 maintained 73.33%, 52.67%, 55.0%, and 54.0% of its original activity after 60 min of exposure to Sunlight, Surf, Maq, and Omo, respectively. Adding crude lipase to enzyme-free laundry detergents significantly enhanced their cleaning efficacy, completely removing oil stains from cotton fabric. This performance of R. terrigena veli18 crude lipase highlights its potential as an effective detergent bio-additive. Full article