Search Results (2,031)

Pseudomonas aeruginosa poses significant health threats due to its multidrug-resistant profile, particularly affecting immunocompromised individuals. The pathogen’s ability to produce virulence factors and antibiotic-resistant biofilms, orchestrated through quorum-sensing (QS) mechanisms, complicates conventional therapeutic interventions. This review aims to critically assess the potential of anti-QS strategies as alternatives to antibiotics against P. aeruginosa infections. Comprehensive literature searches were conducted using databases such as PubMed, Scopus, and Web of Science, focusing on studies addressing QS inhibition strategies published recently. Anti-QS strategies significantly attenuate bacterial virulence by disrupting QS-regulated genes involved in biofilm formation, motility, toxin secretion, and immune evasion. These interventions reduce the selective pressure for resistance and enhance antibiotic efficacy when used in combination therapies. Despite promising outcomes, practical application faces challenges, including specificity of inhibitors, pharmacokinetic limitations, potential cytotoxicity, and bacterial adaptability leading to resistance. Future perspectives should focus on multi-target QS inhibitors, advanced delivery systems, rigorous preclinical validations, and clinical translation frameworks. Addressing current limitations through multidisciplinary research can lead to clinically viable QS-targeted therapies, offering sustainable alternatives to traditional antibiotics and effectively managing antibiotic resistance. Full article

Background/Objectives: Hemodialysis catheter-related bloodstream infection (HD-CRBSIs) is a main cause of morbidity in hemodialysis. New preventive strategies have emerged, such as using lock solutions with antiseptic or antibiotic capacity. In this study, the antimicrobial effect was analyzed in vitro and with a catheter model of lock solutions of gentamicin (LSG), gentamicin/heparin (LSG/H), and gentamicin/citrate (LSG/C) in clinical and ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus. Methods: The formation, minimum inhibitory concentration, and minimum inhibitory concentration of the biofilm and minimum biofilm eradication concentration of the lock solutions were determined. Additionally, colony-forming unit assays were performed to evaluate the antimicrobial efficacy of the lock solutions in a hemodialysis catheter inoculation model. Results: The minimum inhibitory concentration (MIC) of planktonic cells of both P. aeruginosa and S. aureus for LSG/H and LSG/C was 4 µg/mL. In the minimum biofilm inhibitory concentration (MBIC) tests, the LSG/H was less effective than LSG/C, requiring higher concentrations for inhibition, contrary to the minimum biofilm eradication concentration (MBEC), where LSG/H was more effective. All lock solutions eradicated P. aeruginosa biofilms in the HD catheter model under standard conditions. Nevertheless, under modified conditions, the lock solutions were not as effective versus ATCC and clinical strains of S. aureus. Conclusions: Our analysis shows that the lock solutions studied managed to eradicate intraluminal mature P. aeruginosa in non-tunneled HD catheters under standard conditions. Biofilm inhibition and eradication were observed at low gentamicin concentrations, which could optimize the gentamicin concentration in lock solutions used in HD catheters. Full article

Antibiotic-resistant Pseudomonas aeruginosa presents a critical global health challenge, particularly in hospital-acquired infections. Bacteriophages offer a promising therapeutic avenue due to their ability to target and lyse resistant strains. This study characterizes Pseudomonas phage Banzai, a newly isolated Pbunavirus (family Lindbergviridae) with lytic activity against multiple P. aeruginosa isolates, including multidrug-resistant strains. Genomic analysis revealed a 66,189 bp genome, lacking antibiotic resistance or virulence factors, and suggested a headful packaging mechanism and the presence of a bidirectional component in the replication. In vivo experiments using Galleria mellonella showed therapeutic potential, significantly improving larval survival (87% at 24 h). Host range analysis revealed activity against 13 of 30 P. aeruginosa isolates, including members of O1, O3, O5 and O6 in silico predicted serogroups. Phylogenomic analyses place phage Banzai within the genus Pbunavirus, sharing 94.8% intergenomic similarity with its closest relatives, supporting its classification as a novel species. These findings highlight phage Banzai as a potential candidate for phage therapy, demonstrating genomic stability, a strictly lytic lifestyle, and in vivo efficacy. Full article

Antimicrobial resistance (AMR) is a growing global health threat, with wild birds increasingly recognized as potential reservoirs of resistant pathogens and as sentinels of environmental AMR. This study investigated the occurrence and AMR profiles of Gram-negative bacteria isolated from wild birds that died at the Wildlife Rescue Center in Vanzago, Lombardy, in 2024. Cloacal swabs were collected from 112 birds representing various ecological categories. A total of 157 Gram-negative bacteria were isolated and identified, including clinically relevant genera and species, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Salmonella spp., Pseudomonas aeruginosa, and Acinetobacter baumannii. Antimicrobial susceptibility testing revealed resistance to first-line and critically important antimicrobials, including those exclusively authorized for human use. Notably, a phenotype compatible with Extended-Spectrum Beta-Lactamase (ESBL) production was detected in four out of ten (40%) K. pneumoniae isolates. In addition, 20 out of the 157 (12.7%) isolated bacteria phenotypically exhibited a resistance profile indicative of AmpC beta-lactamase (AmpC) production, including Enterobacter spp. and P. aeruginosa. Resistance patterns were particularly interesting in birds with carnivorous, scavenging, or migratory-associated behaviors. These findings highlight the role of wild birds in the ecology and dissemination of antimicrobial-resistant bacteria (ARB) and highlight the need for wildlife-based AMR monitoring programs as part of a One Health approach. Full article

Background: The COVID-19 pandemic has profoundly altered the clinical and microbiological landscape of respiratory tract infections (RTIs), potentially reshaping pathogen distribution and antimicrobial resistance (AMR) profiles across care settings. Objectives: The objective of this study was to assess temporal trends in respiratory bacterial pathogens, antimicrobial resistance, and polymicrobial infections across three pandemic phases—pre-COVID (2018–2019), COVID (2020–2022), and post-COVID (2022–2024)—in hospitalized and ambulatory patients. Methods: We retrospectively analyzed 1827 respiratory bacterial isolates (hospitalized patients, n = 1032; ambulatory patients, n = 795) collected at a tertiary care center in Northern Italy. Data were stratified by care setting, anatomical site, and pandemic phase. Species identification and susceptibility testing followed EUCAST guidelines. Statistical analysis included chi-square and Fisher’s exact tests. Results: In hospitalized patients, a significant increase in Pseudomonas aeruginosa (from 45.5% pre-COVID to 58.6% post-COVID, p < 0.0001) and Acinetobacter baumannii (from 1.2% to 11.1% during COVID, p < 0.0001) was observed, with 100% extensively drug-resistant (XDR) rates for A. baumannii during the pandemic. Conversely, Staphylococcus aureus significantly declined from 23.6% pre-COVID to 13.7% post-COVID (p = 0.0012). In ambulatory patients, polymicrobial infections peaked at 41.2% during COVID, frequently involving co-isolation of Candida spp. Notably, resistance to benzylpenicillin in Streptococcus pneumoniae reached 80% (4/5 isolates) in hospitalized patients during COVID, and carbapenem-resistant P. aeruginosa (CRPA) significantly increased post-pandemic in ambulatory patients (0% pre-COVID vs. 23.5% post-COVID, p = 0.0014). Conclusions: The pandemic markedly shifted respiratory pathogen dynamics and resistance profiles, with distinct trends observed in hospital and community settings. Persistent resistance phenotypes and frequent polymicrobial infections, particularly involving Candida spp. in outpatients, underscore the need for targeted surveillance and antimicrobial stewardship strategies. Full article

The textile industry’s reliance on synthetic dyes contributes significantly to pollution, highlighting the need for sustainable alternatives like biopigments. This study investigates the production and application of the biopigment prodigiosin, which was produced by Pseudomonas putida with a yield of 1.85 g/L. Prodigiosin was prepared under acidic, neutral, and alkaline conditions, resulting in varying protonation states that influenced its affinity for cotton and polyester fibers. Three surfactants (anionic, cationic, non-ionic) were tested, with non-ionic Tween 80 yielding a promising color strength (above 4) and fastness results with neutral prodigiosin at 1.3 g/L. Cotton and polyester demonstrated good washing (color difference up to 14 for cotton, 5 for polyester) and light fastness (up to 15 for cotton, 16 for polyester). Cellulose acetate, used in the conventional printing process as a thickener, produced superior color properties compared to commercial thickeners. Neutral prodigiosin achieved higher color strength, and cotton fabrics displayed halochromic properties, distinguishing them from polyester, which showed excellent fastness. Prodigiosin-printed samples also exhibited strong antimicrobial activity against Pseudomonas aeruginosa and retained halochromic properties over 10 pH cycles. These findings suggest prodigiosin as a sustainable dye alternative and pH sensor, with potential applications in biomedical materials, such as antimicrobial and pH-responsive wound dressings. Full article

This investigation examines the influence of P. dabryanus density on the growth performance of P. nigromaculatus and the structural and functional dynamics of paddy soil microbial communities within a rice–frog–loach integrated aquaculture system. Field experiments were conducted with five density gradients of P. dabryanus (0.5, 1.0, 1.5, 2.0, and 2.5 × 10⁴ individuals/667 m²), designated as RFLS0.5, RFLS1.0, RFLS1.5, RFLS2.0, and RFLS2.5, respectively. Control treatments included rice monoculture (RM) and rice–frog co-culture (RFS). These findings demonstrated that as the density of loach increased, the weight gain ratio of P. nigromaculatus showed a unimodal pattern, reaching its peak in RFLS1. Metagenomic analysis on paddy soil revealed that the RFLS1 facilitated the enrichment of nitrogen-fixing bacteria (Proteobacteria), while concurrently suppressing proliferation of the potential pathogen Pseudomonas aeruginosa and microbial markers in metal-contaminated environments of Usitatibacter rugosus. Further, functional profiling indicated that RFLS1 group reached a peak activity in amino acid metabolism (14.52 ± 0.09%) and carbohydrate metabolism (14.44 ± 0.06%) and showed a higher proportion of glycosyltransferase (GT) abundance (41.93 ± 0.02%) than other groups. In summary, the optimal stocking density of P. dabryanus in rice–frog–loach integrated systems was determined to be 1.0 × 10⁴ individuals/667 m². This density not only promotes the growth of P. nigromaculatus but also improves the structure of paddy soil microbial communities. Full article

Heavy metal-contaminated soil poses a severe threat to environmental quality and human health, calling for eco-friendly and efficient remediation strategies. This study explored the use of biochar-immobilized copper-resistant Pseudomonas aeruginosa to remediate copper-contaminated soil and promote growth of Chinese milk vetch (Astragalus sinicus L.). Indoor pot experiments compared four groups: copper-contaminated soil (control), soil with biochar, soil with free bacteria, and soil with biochar-immobilized bacteria (IM). Results showed IM had the most significant effects on soil properties: it raised pH to 7.04, reduced bioavailable copper by 34.37%, and increased catalase (3.48%) and urease (78.95%) activities. IM also altered soil bacterial communities, decreasing their richness and evenness (alpha diversity) while shifting community composition. For Chinese milk vetch, IM reduced leaf malondialdehyde (a marker of oxidative stress) by 15%, increased total dry weight by 90%, and lowered copper accumulation in roots (18.62%) and shoots (60.33%). As a nitrogen-fixing plant, the vetch’s nitrogen fixation in roots and shoots rose by 82.70% and 57.08%, respectively, under IM. These findings demonstrate that biochar-immobilized Pseudomonas aeruginosa is a promising in situ amendment for remediating copper-contaminated soil and boosting plant growth. Full article

Background/Objectives: Antimicrobial resistance (AMR) is a health related threat world-wide. Biosynthesized gold nanoparticles (AuNPs) using plant extracts have been reported to exhibit certain biological activity. This study aimed to biosynthesize AuNPs using an aqueous extract of Eruca sativa leaves and to evaluate their biocompatibility, antimicrobial activity, and antioxidant properties. Methods: AuNPs were biosynthesized using an aqueous extract of Eruca sativa leaves. Their biocompatibility was evaluated through hemolytic activity and assessments of hepatic and renal functions in rats. AuNPs were biologically evaluated as antimicrobial and antioxidant agents. Results: The AuNPs exhibited particle sizes of 27.78 nm (XRD) and 69.41 nm (AFM). Hemolysis assays on red blood cells revealed negligible hemolytic activity (<1%). Hepatic enzyme levels, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were studied. ALT, AST, and ALP levels showed no significant changes compared to the negative control. However, LDH levels were elevated at higher concentration (52.8 µg/mL), while the lower concentration (26.4 µg/mL) appeared to be safer. Renal biomarkers, urea and creatinine, showed no significant changes at either concentration, indicating minimal nephrotoxicity. The antimicrobial activity of AuNPs, plant extract, and gold salt was tested against five microorganisms: two Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae), two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and a fungal strain (Candida albicans). The AuNPs exhibited minimum inhibition concentrations (MICs) of 13.2 µg/mL against S. aureus and S. pneumoniae, 26.4 µg/mL against E. coli and C. albicans, and 39.6 µg/mL against P. aeruginosa, suggesting selectivity towards Gram-positive bacteria. Furthermore, the AuNPs demonstrated strong antioxidant activity, surpassing that of vitamin C. Conclusions: The biosynthesized AuNPs exhibited promising biocompatibility, selective antimicrobial properties, and potent antioxidant activity, supporting their potential application in combating the AMR. Full article

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/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

Infections with multidrug-resistant (MDR) organisms remain a significant cause of morbidity and mortality among liver transplant recipients, despite advances in surgical techniques and immunosuppressive therapy. This prospective observational study aimed to evaluate the impact of targeted perioperative antibiotic prophylaxis against MDR Gram-negative bacteria on postoperative infections and mortality in liver transplant recipients. Seventy-nine adult patients who underwent liver transplantation and were admitted to the ICU for more than 24 h postoperatively were included. Demographics, disease severity scores, comorbidities, and lengths of ICU and hospital stay were recorded. Colonization with carbapenem-resistant Gram-negative bacteria was assessed via preoperative and postoperative cultures from the blood, urine, rectum, and tracheal secretions. Patients were divided into two groups: those with MDR colonization or infection who received targeted prophylaxis and controls who received standard prophylaxis. Infectious complications (30.4%) occurred significantly less frequently than non-infectious ones (62.0%, p = 0.005). The most common infections were bacteremia (22.7%), pneumonia (17.7%), and surgical site infections (2.5%), with most events occurring within 15 days post-transplant. MDR pathogens isolated included Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. Although overall complication and mortality rates at 30 days and 3 months did not differ significantly between groups, the targeted prophylaxis group had fewer infectious complications (22.8% vs. 68.5%, p = 0.008), particularly bacteremia (p = 0.007). Infection-related mortality was also significantly reduced in this group (p = 0.039). These findings suggest that identification of MDR colonization and administration of targeted perioperative antibiotics may reduce septic complications in liver transplant patients. Further prospective studies are warranted to confirm benefits on outcomes and resource utilization. Full article

Photodynamic inactivation (aPDI) involves the interaction of three components: non-toxic photosensitizer molecules (PS), low-intensity visible light, and molecular oxygen. This interaction leads to the generation of toxic reactive oxygen species. The present work demonstrated the efficacy of light-induced antimicrobial photodynamic inactivation against Pseudomonas aeruginosa and Pseudomonas putida using 5-aminolevulinic acid (5-ALA) as a prodrug to produce the photosensitizer protoporphyrin IX. The photoeradication efficiency of these pathogens under blue (405 nm; 45 mW cm⁻²) and red (635 nm; 53 mW cm⁻²) light was investigated. Results showed that at least 30 min of blue light irradiation was necessary to achieve a 99.999% reduction of P. aeruginosa, whereas red light was less effective. P. putida exhibited limited susceptibility under similar conditions. To enhance aPDI efficiency, exogenous glucose was added alongside 5-ALA, which significantly increased the photodynamic efficacy—particularly against P. aeruginosa—leading to complete eradication after just 5 min of exposure. Spectroscopic analyses confirmed that glucose increased the levels of protoporphyrin IX, which correlated with enhanced photodynamic efficacy. Furthermore, multiple aPDI exposure reduced key virulence factors, including alkaline protease activity, biofilm formation, and swarming motility (in P. aeruginosa). These findings suggest that 5-ALA-mediated photodynamic inactivation offers a promising strategy to improve efficacy against resistant Gram-negative pathogens. Full article

Many bacteria, such as Pseudomonas aeruginosa, have encoded many toxins like RhsP2 that target non-coding RNAs (ncRNAs) in a similar mechanism to ART components; bacterial RNA loses its function of amino acid translation. A virtual screening approach was used to investigate RhsP2, which targets 16s rRNAs and then disrupts the translation of bacterial amino acids to proteins. Rifamycin is the bioreference as it forms a stable complex with the bacterial RNA in its active sites. Using different docking software can determine the best predicted conformations between RhsP2/16S and rRNA, and analyzing the docking score for both Affinity Binding and the root mean square deviation (RMSD) of particle coordinates helps choose the most appropriate drugs by using tools such as bioinformatics platforms and databases. Full article

The holistic use of Moringa oleifera Lam. seeds is not as popular amongst rural South Africans. This study screened for the phytochemicals, antimicrobial, and antioxidant potentials as well identifying the compounds in the oils of South African Moringa seed oils using cost-effective thin layer chromatography bioautography and dot blot assays, because fewer studies have been conducted using seed samples from this country. The results obtained indicated that the best oil extract yield (24.04%) was obtained for hexane from 60.10 g of powdered seeds. The yield of the other extracts ranged from 6.2 to 9.5%. Positive test results were obtained for terpenoids, steroids, alkaloids, flavonoids, phenols, and tannins, with potentially good antioxidant properties for scavenging free radicals from 2,2-diphenyl-1-picrylhydrazyl (DPPH) and good antimicrobial activity against Acinetobacter baumannii (BAA 747), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 27853), and Pseudomonas aeruginosa (ATCC 27853), with the best zone of inhibition of 314.2 mm² obtained for oil extracted with hexane, followed by dichloromethane, methanol, and acetone oil extracts, respectively. The best minimum inhibitory concentration (MIC) of 0.032 mg/mL against P. aeruginosa was recorded for the hexane oil, compared with ciprofloxacin, which had an MIC of 0.0039 mg/mL against the same pathogen. The identification of the in-oil compounds proposed to mitigate inhibitory activity against the test microbes was carried out through GC-MS analysis matching our results with the GC-MS library. These compounds included ursane-3,16-diol, azetidin-2-one, 1-benzyl-4à-methyl, dibutyl phthalate, 4-methyl-2,4-bis(p-hydroxyphenyl)pent-1-ene, 1H-pyrrole-2,5-dione, 3-ethyl-4-methyl, octopamine rhodoxanthin, 29,30-dinorgammacerane-3,22-diol, 21,21-dimethy, cholan-24-oic acid, 3,7-dioxo, and benzyl alcohol. These are in addition to the stability-indicating marker compounds like oleic acid (54.9%), 9-Octadecenoic acid (z)-, methyl ester (23.3%), n-hexadecanoic acid (9.68%), among others observed over a five year period. Full article