Pseudomonas aeruginosa: pathogenesis, virulence factors, antibiotic resistance, interaction with host, technology advances and emerging therapeutics

A CRISPR/Cas12a-based colorimetric AuNPs biosensor for naked-eye detection of pathogenic bacteria in clinical samples

Pathogenic bacteria, such as Pseudomonas aeruginosa, pose significant threats to public health due to their multidrug resistance and association with severe infections. Rapid and reliable detection methods are crucial for timely treatment and effective infection control, especially in resource-limited settings. In this study, we developed a CRISPR/Cas12a-based colorimetric biosensor that leverages Cas12a's trans-cleavage activity to release left single-stranded DNA (lDNA). The released lDNA facilitates hybridization with clDNA-functionalized gold nanoparticles (AuNPs), resulting in a visible color change. The biosensor achieved a detection limit of 100 CFU/reaction for P. aeruginosa within 2 hours, with excellent specificity and robustness, as validated in spiked sputum and blood samples. Clinical testing using 32 blood samples (13 positive, 19 negative) confirmed its high diagnostic accuracy, achieving an AUC of 1 in ROC curve analysis. The platform's simplicity, robustness, and programmability suggest its broad potential for rapid infectious disease diagnostics, particularly in low-resource settings.

Development and analysis of chitin/cellulose reinforced galactomannan fluidic hydrogel for drug delivery application

Rising demand for advanced materials in biomedical applications has made the development of effective hydrogels a critical focus, especially for drug delivery. Herein, a novel fluidic hydrogel with high drug-loading (>95 %) capacity was developed for controlled release of acetylsalicylic acid. Nature-derived galactomannan (GM) was served as the hydrogel matrix, and chitin nanocrystals (ChNC) and cellulose nanocrystals (CNC) were used to enhance structure and antimicrobial properties. Physical crosslinking of the components were tuned to optimize the porosity, flowability, and mechanical strength of the materials, as well as improving rheology and enabling rapid self-healing within 60 s. Co-culturing experiments demonstrate excellent biocompatibility of both ChNC@GM and CNC@GM hydrogels. Moreover, ChNC@GM shows superior 82 % antimicrobial activity, and the hydrogel exhibits pH-responsive drug release. Therefore, the proposed fluidic hydrogel may act as promising material for applications fields of wound healing, drug delivery, and biomedical engineering, etc.

Isolation, identification and the pathogenicity characterization of Pseudomonas putida 1C3 and its activation on immune responses in Japanese flounder (Paralichthys olivaceus)

The outbreak of mass mortality of Japanese flounder occurred in an aquaculture farm in Hebei province of China. This study isolated and identified Pseudomonas putida as the dominant bacterium from diseased Japanese flounder (Paralichthys olivaceus) based on morphological, physiological, biochemical characteristics, 16S rRNA gene sequencing, and whole-genome sequencing. Pathogenicity assessment, histopathological analysis, and host immune response were investigated. Results demonstrated that P. putida was pathogenic, causing acute enteritis and multiple organ damage in infected fish. The median lethal dose (LD50) was determined as 2.66 × 106 CFU/g. Transcriptome analysis of the spleen at three post-infection timepoints revealed a robust immune response, with significantly upregulation of immune pathways and downregulation of metabolic functions. Key cytokines (il-1β, il-6, tnf, il-8, il-12, cxcl10, ccl2) were significantly upregulated, indicating intense immune activation. Notably, the P. putida strain exhibited a multidrug-resistant phenotype and harbored multiple drug resistance genes and virulence factors. This is the first report linking P. putida to disease in P. olivaceus, comprehensively elucidating its causative role and the host immune response in Japanese flounder culture.

The evolution of carbapenem-resistant Pseudomonas aeruginosa in the COVID-19 era: A global perspective and regional insights

OBJECTIVE

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a major contributor to healthcare-associated infections globally. The aim of this study was the impact of the COVID-19 pandemic on the genomic characteristics of P. aeruginosa, particularly clinical CRPA isolates.

METHODS

Clinical data of each patient were collected from the clinical and medical record system. Whole-genome sequencing and bioinformatics analyses were performed to characterize the antibiotic resistance genes (ARGs) and evolutionary dynamics of these isolates. Furthermore, big data analysis was employed to elucidate the genomic characteristics of P. aeruginosa genomes across different periods on a global scale. Statistical analyses were applied to ensure the reliability of the findings.

RESULTS

A total of 628 non-duplicate CRPA isolates were collected, with 256 isolates from before the COVID-19 pandemic and 372 during the pandemic. Only 26.59% of isolates carried carbapenemases, predominantly GES-14, and carbapenemase diversity decreased during the pandemic. However, the diversity of CRPA sequence types (STs) increased, with ST235 and ST244 emerging as the most prevalent clones. The Antibiotic resistance genes (ARGs) number carried by CRPA isolates significantly decreased during the pandemic (P < 0.05), with notable differences in 24 ARGs and 14 virulence factors (VFs) between prepandemic and pandemic periods (χ2 test, P < 0.05). O11 was the predominant serotype across all periods. Global analysis revealed a significant reduction in ARGs in strains from China and Australia (P < 0.01) during the pandemic. Analysis of the global epidemic clones ST244 and ST235 indicated that ARGs in ST244 P. aeruginosa increased significantly during the pandemic.

CONCLUSIONS

Our study highlights the critical need for ongoing surveillance of the evolutionary effects of the COVID-19 pandemic on clinical CRPA isolates, offering an essential theoretical basis for the development of effective and rational control strategies in clinical settings.

Potential of vB_Pa_ZCPS1 phage embedded in situ gelling formulations as an ocular delivery system to attenuate Pseudomonas aeruginosa keratitis in a rabbit model

Pseudomonas aeruginosa keratitis (or pink eye) is a challenging ocular infection that causes serious complications due to the deficiency of effective antibiotic treatment. Thus, in this study we isolated and characterized a specific bacteriophage, phage vB_Pa_ZCPS1, to be used to formulate an in situ- gel loaded bacteriophage for an in vivo rabbit infection treatment model. Phage vB_Pa_ZCPS1 is a double-stranded DNA bacterial virus, of 46,135 bp encoding 75 open reading frames (ORFs) with no antibiotic resistance genes detected. Moreover, it has a podoviral morphotype from the Caudoviricetes class with a 62.4 nm capsid and a short inflexible tail of around 18.8 nm, as indicated by the transmission electron microscope (TEM). Phage vB_Pa_ZCPS1 presented good stability to the UV exposure and a wide range of pH values from 3.0 to 11.0. In addition, the phage-bacteria dynamics study showed that phage vB_Pa_ZCPS1 was effective against P. aeruginosa, especially at low multiplicities of infections (MOIs), including 0.001, 0.01, and 0.1. Respectively, it was loaded to the characterized in situ gel composed of 14 % Pluronic F-127 and 1.5 % HPMC K4M polymer. The in situ-gel has a gelling time of 30 s ± 1, and a temperature of 33 °C ± 1, where the viscosity of the gel increases 10-fold. For the in vivo trial, the infected group treated with phage presented improved clinical outcomes, where the histopathological analysis revealed normal corneal thickness and intact corneal stratified squamous epithelium. Thus, the in situ-gel loaded phage vB_Pa_ZCPS1 could be a potential candidate approach to treat P. aeruginosa keratitis.

Transcriptional response study of auto inducer-2 regulatory system in Escherichia coli harboring blaNDM

BACKGROUND

The emergence of carbapenem resistance in gram-negative bacteria such as Escherichia coli is one of the world's most urgent public health problems. E. coli, which encounter a diverse range of niches in host can rapidly adapt to the changes in surrounding environment by coordinating their behavior via production, release and detection of signal molecules called autoinducers through a cell density dependent communication system known as quorum sensing. Here, in this study we investigated whether imipenem, and acyl homoserine lactone quorum sensing signal molecules influence the transcriptional response within lsr and lsrRK operon which are associated with auto inducer-2 mediated quorum sensing in E. coli. Two E. coli isolates carrying blaNDM were treated with 10% SDS for 20 consecutive days, resulting in the successful elimination of the blaNDM encoding plasmid from one isolate. Plasmid was extracted from the isolate and was transformed into recipient E. coli DH5α by electroporation. The native type, plasmid-cured type, transformant, and E. coli DH5α were allowed to grow under eight different inducing conditions and the transcriptional responses of lsr and lsrRK operons were studied by quantitative real-time PCR method.

RESULTS

The findings of this study highlight the distinct effects of imipenem and AHL on the transcriptional responses of the lsrB,lsrR, and lsrK genes in native type, plasmid cured type, transformant, and E. coli DH5α.

CONCLUSION

This study provides a basis for further research to elucidate different inducing conditions including antibiotics and autoinducers that could switch on the quorum sensing circuit in carbapenem non-susceptible E. coli, one of the world's most urgent public health threats.

Antibiofilm, regenerative and bone homeostasis potential of the synergistic association of synoeca-MP peptide with chlorhexidine in oral cavity opportunistic infections

OBJECTIVE

Synoeca-MP is an antimicrobial peptide that belongs to the class of defense peptides, known for their antimicrobial and immunomodulatory properties. To evaluate in vitro the association between synoeca-MP peptide and chlorhexidine, regarding their antimicrobial and antibiofilm activities, saliva stability, effect on tissue repair, bone resorption processes, and mineralized matrix formation.

DESIGN

Initially, the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiofilm concentration were determined. The synergism and degradation of synoeca-MP and chlorhexidine in human saliva were assessed. Furthermore, biocompatibility was evaluated using MTT assays, hemolytic assays, and proliferation and migration assays of periodontal ligament cells. Finally, bone homeostasis was evaluated through osteoclastogenesis assays, alkaline phosphatase determination, and mineralized matrix formation assay with SaOs-2 and ligament cells.

RESULTS

The antimicrobial and antibiofilm activity against the tested microorganisms was confirmed. Low synergistic concentrations of the synoeca-MP and chlorhexidine combination inhibited tested microorganisms. The association of these molecules remained stable in healthy saliva. Nevertheless, it degraded as the severity of periodontal disease increased. Additionally, lower synergistic concentrations of the combination were not cytotoxic to human cells, promoted the proliferation and migration of ligament cells, inhibited osteoclastogenesis, and increased mineral matrix formation of ligament cells and SaOs-2.

CONCLUSIONS

Synoeca-MP and chlorhexidine combination shows potential for oral diseases treatment, as evidenced by its antimicrobial activity, regenerative potential, saliva stability, and bone homeostasis. It may be particularly effective for opportunistic oral infections and in conjunction with mechanical therapy.

A deadly taste: linking bitter taste receptors and apoptosis

Humans can perceive five canonical tastes: salty, sour, umami, sweet, and bitter. These tastes are transmitted through the activation of ion channels and receptors. Bitter taste receptors (Taste Family 2 Receptors; T2Rs) are a sub-family of 25 G-protein coupled receptor (GPCR) isoforms that were first identified in type II taste bud cells. T2Rs are activated by a broad array of bitter agonists, which cause an increase in intracellular calcium (Ca2+) and a decrease in cyclic adenosine 3',5'-monophosphate (cAMP). Interestingly, T2Rs are expressed beyond the oral cavity, where they play diverse non-taste roles in cell physiology and disease. Here, we summarize the literature that explores the role of T2Rs in apoptosis. Activation of T2Rs with bitter agonists induces apoptosis in several cancers, the airway epithelia, smooth muscle, and more. In many of these tissues, T2R activation causes mitochondrial Ca2+ overload, a main driver of apoptosis. This response may be a result of T2R cellular localization, nuclear Ca2+ mobilization and/or a remnant of the established immunological roles of T2Rs in other cell types. T2R-induced apoptosis could be pharmacologically leveraged to treat diseases of altered cellular proliferation. Future work must explore additional extra-oral T2R-expressing tissues for apoptotic responses, develop methods for in-vivo studies, and discover high affinity bitter agonists for clinical application.

Synchronous Sterilization and Immunoreaction Termination for Corneal Transparency Protection in Treating Pseudomonas aeruginosa Induced Bacterial Keratitis

In the treatment of infectious keratitis, therapeutic strategies often prioritize enhancing bactericidal efficacy. However, endotoxins released from Gram-negative bacteria cause inflammatory reaction, leading to corneal structural damage and scar formation. Given that polymyxin B (PMB) can bind and neutralize lipopolysaccharide (LPS), this study employs large-pore mesoporous silica nanoparticles (lMSNs) grafted with PMB as carriers for cationic antibacterial carbon quantum dots (CQDs) to prepare CQD@lMSN-PMB, which enables synchronous sterilization and endotoxin neutralization. In the acidic infectious microenvironment, the accelerated release of CQDs eliminates 99.88% bacteria within 2 h, effectively substituting immune mediated sterilization. Notably, CQD@lMSN-PMB exhibits exceptional LPS neutralization performance (2.22 µg LPS/mg CQD@lMSN-PMB) due to its high specific surface area. In an infectious keratitis model, inflammation subsides significantly within the first day of CQD@lMSN-PMB intervention and is completely resolved by day 3. By day 2, interleukin-1β, interleukin-6 and tumor necrosis factor-α in CQD@lMSN-PMB group decrease by 86.99%, 91.15%, and 77.56%, respectively, compared to the CQDs-only sterilization group. Ultimately, corneal integrity and transparency are preserved, with suppressed expressions of fibrosis-related factors including matrix metalloproteinase 9, transforming growth factor-β and α-smooth muscle actin. Therefore, this synchronous sterilization and endotoxin neutralization strategy outperforms monotherapy strategies focused solely on sterilization or endotoxin neutralization.

Optimized peptide inhibitor Aqs1C targets LasR to disrupt quorum sensing and biofilm formation in Pseudomonas aeruginosa: Insights from MD simulations and in vitro studies

Pseudomonas aeruginosa (PA) is a critical pathogen, and its antibiotic resistance is largely driven by the quorum-sensing regulator LasR. Herein, we report the design, synthesis, and characterization of Aqs1C, a mutated peptide derivative of Aqs1, optimized to inhibit LasR and its quorum-sensing pathway. By introducing a targeted mutation, Aqs1C exhibited enhanced stability and binding affinity for LasR protein compared to its predecessor, Aqs1B. Using molecular dynamics simulations (MDS), the Aqs1C-LasR complex demonstrated a marked increase in structural stability, reflected in reduced root mean square deviation (RMSD) values and lower binding free energy. Electrostatic complementarity analysis showed stronger and more favorable interactions between Aqs1C and LasR. Further, GaMD experiments were able to reproduce the binding state between Aqs1C and LasR, indicating the binding mechanism between them. These molecular insights correlated with functional in vitro assays. Aqs1C effectively inhibited quorum-sensing-associated virulence factors in PA, involving biofilm formation (77.6 % inhibition), pyocyanin production (75.7 % inhibition), protease secretion (61.1 % inhibition), and rhamnolipid production (74.1 % inhibition), at a 100 μg/mL concentration, in a comparable or superior pattern to azithromycin (AZM). Molecular modelling, MDS, and GaMD insights and in vitro assays established Aqs1C as a promising candidate for therapeutic development to mitigate PA infections through targeted quorum-sensing disruption.

A targeted and synergetic nano-delivery system against Pseudomonas aeruginosa infection for promoting wound healing

Purpose

Pseudomonas aeruginosa infection is the most common pathogen in burn wound infections, causing delayed wound healing and progression to chronic wounds. Therefore, there is an urgent need to develop antimicrobial agents that can promote wound healing for effectively treating infected wounds.

Patients and methods

Using magnetic stirring and ultrasound to synthesize Apt-pM@UCNPmSiO2-Cur-CAZ. The nanosystems were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), and ultraviolet-visible spectrophotometry (UV-Vis). Flow cytometry, bacterial LIVE/DEAD staining and scanning electron microscopy were performed to assess the in vitro antibacterial and anti-biofilm effects of the nanosystems. The wound healing potential and in vivo toxicity of the nanosystems were evaluated in a mouse skin wound model.

Results

The Apt-pM@UCNPmSiO2-Cur-CAZ synthesized exhibited uniform circular shape with a Zeta potential of -0.8 mV. In vitro, Apt-pM@UCNPmSiO2-Cur-CAZ demonstrated superior antibacterial effects compared to standalone antibiotics. Bacteria treated with Apt-pM@UCNPmSiO2-Cur-CAZ showed varying degrees of deformation and shrinkage, resulting in severe damage to the bacterial cells. Additionally, Apt-pM@UCNPmSiO2-Cur-CAZ can inhibit and eradicate bacterial biofilms, while also targeting bacteria for enhanced antibacterial efficacy. Interestingly, the NIR light could enhance the antibacterial and anti-biofilm effects of Apt-pM@UCNPmSiO2-Cur-CAZ due to the photodynamic action. In a mouse skin wound infection model, the nanosystem effectively eliminated wound bacteria, promoting the healing of Pseudomonas aeruginosa-infected wounds without significant toxic effects.

Conclusion

Apt-pM@UCNPmSiO2-Cur-CAZ is a novel targeted nano-delivery system with promising potential in combating Pseudomonas aeruginosa infections, and it may serve as a new therapeutic approach for treating skin wound infections.

tesG expression as a potential clinical biomarker for chronic Pseudomonas aeruginosa pulmonary biofilm infections

BACKGROUND

Pseudomonas aeruginosa infections in the lungs affect millions of children and adults worldwide. To our knowledge, no clinically validated prognostic biomarkers for chronic pulmonary P. aeruginosa infections exist. Therefore, this study aims to identify potential prognostic markers for chronic P. aeruginosa biofilm lung infections.

METHODS

Here, we screened the expression of 11 P. aeruginosa regulatory genes (tesG, algD, lasR, lasA, lasB, pelB, phzF, rhlA, rsmY, rsmZ, and sagS) to identify associations between clinical status and chronic biofilm infection.

RESULTS

RNA was extracted from 210 sputum samples from patients (n = 70) with chronic P. aeruginosa lung infections (mean age; 29.3-56.2 years; 33 female). Strong biofilm formation was correlated with prolonged hospital stays (212.2 days vs. 44.4 days) and increased mortality (46.2% (18)). Strong biofilm formation is associated with increased tesG expression (P = 0.001), influencing extended intensive care unit (P = 0.002) or hospitalisation stays (P = 0.001), pneumonia risk (P = 0.006), and mortality (P = 0.001). Notably, tesG expression is linked to the modulation of systemic and sputum inflammatory responses and predicts biofilm biomass.

CONCLUSIONS

This study provides the first clinical dataset of tesG expression levels as a predictive biomarker for chronic P. aeruginosa pulmonary infections.

Whole proteome-integrated and vaccinomics-based next generation mRNA vaccine design against Pseudomonas aeruginosa-A hierarchical subtractive proteomics approach

Pseudomonas aeruginosa (P. aeruginosa) is a multidrug-resistant opportunistic pathogen responsible for chronic obstructive pulmonary disease (COPD), cystic fibrosis, and ventilator-associated pneumonia (VAP), leading to cancer. Developing an efficacious vaccine remains the most promising strategy for combating P. aeruginosa infections. In this study, we employed an advanced in silico strategy to design a highly efficient and stable mRNA vaccine using immunoinformatics tools. Whole proteome data were utilized to identify highly immunogenic vaccine candidates using subtractive proteomics. Three extracellular proteins were prioritized for T- and linear B-cell epitope prediction. Beta-definsin protein sequence was incorporated as an adjuvant at the N-terminus of the construct. A total of 3 CTL, 3 HTL, and 3 linear B cell highly immunogenic epitopes were combined using specific linkers to design this multi-peptide construct. The 5' and 3' UTR sequences, Kozak sequence with a stop codon, and signal peptides followed by a poly-A tail were incorporated into the above vaccine construct to create our final mRNA vaccine. The vaccines exhibited antigenicity scores >0.88, ensuring high antigenicity with no allergenic or toxic. Physiochemical properties analysis revealed high solubility and thermostability. Three-dimensional structural analysis determined high-quality structures. Vaccine-receptor docking and molecular dynamic simulations demonstrated strong molecular interactions, stable binding affinities, dynamic nature, and structural stability of this vaccine, with significant immunogenic responses of the immune system against the vaccine. The immunological simulation indicates successful cellular and humoral immune responses to defend against P. aeruginosa infection. Validation of the study outcomes necessitates both experimental and clinical testing.

Designing a multi-epitope vaccine against Pseudomonas aeruginosa via integrating reverse vaccinology with immunoinformatics approaches

Pseudomonas aeruginosa is a typically opportunistic pathogen responsible for a wide range of nosocomial infections. In this study, we designed two multi-epitope vaccines targeting P. aeruginosa proteins, incorporating cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and linear B lymphocyte (LBL) epitopes identified using reverse vaccinology and immunoinformatics approaches. The vaccines exhibited favorable physicochemical properties, including stability, solubility, and optimal molecular weight, suggesting their potential as viable candidates for vaccine development. Molecular docking studies revealed strong binding affinity to Toll-like receptors 1 (TLR1) and 2 (TLR2). Furthermore, molecular dynamics simulations confirmed the stability of the vaccine-TLR complexes over time. Immune simulation analyses indicated that the vaccines could induce robust humoral and cellular immune responses, providing a promising new approach for combating P. aeruginosa infections, particularly in the face of increasing antibiotic resistance.

Calprotectin elicits aberrant iron starvation responses in Pseudomonas aeruginosa under anaerobic conditions

Pseudomonas aeruginosa is an opportunistic pathogen that uses several mechanisms to survive in the iron-limiting host environment. The innate immune protein calprotectin (CP) sequesters ferrous iron [Fe(II)], among other divalent transition metal ions, to limit its availability to pathogens. CP levels are increased in individuals with cystic fibrosis (CF), a hereditary disease that leads to chronic pulmonary infection by P. aeruginosa. We previously showed that aerobic CP treatment of P. aeruginosa induces a multi-metal starvation response that alters expression of several virulence properties. However, the CF lung is a hypoxic environment due to the growth of P. aeruginosa in dense biofilms. Here, we report that anaerobic CP treatment of P. aeruginosa induces many processes associated with an aerobic iron starvation response, including decreased phenazine production and increased expression of the PrrF small regulatory RNAs (sRNAs). However, the iron starvation response elicited by CP in anaerobic conditions shows characteristics that are distinct from responses observed in aerobic growth, including a lack of siderophore production and increased induction of genes for the FeoAB Fe(II) and Phu heme uptake systems. Also distinct from aerobic conditions, CP treatment induces expression of genes for predicted manganese transporters MntH1 and MntH2 during anaerobic growth while eliciting a less robust zinc starvation response compared to aerobic conditions. Induction of mntH2 is dependent on the PrrF sRNAs, suggesting a novel example of metal regulatory cross-talk. Thus, anaerobic CP treatment results in a multi-metal starvation response with key distinctions from aerobic conditions, revealing differences in P. aeruginosa metal homeostasis during anaerobic growth.IMPORTANCEIron is critical for most microbial pathogens, and the innate immune system sequesters this metal to limit microbial growth. Pathogens must overcome iron sequestration to survive during infection. For many pathogens, iron homeostasis has primarily been studied in aerobic conditions. Nevertheless, some host environments are hypoxic, including chronic lung infection sites in individuals with cystic fibrosis (CF). Here, we use the innate immune protein calprotectin, which sequesters divalent metal ions including Fe(II), to study the anaerobic iron starvation response of a common CF lung pathogen, Pseudomonas aeruginosa. We report several distinctions of this response during anaerobiosis, highlighting the importance of carefully considering the host environment when investigating the role of nutritional immunity in host-pathogen interactions.

Molecular mechanisms and therapeutic targets of acute exacerbations of chronic obstructive pulmonary disease with Pseudomonas aeruginosa infection

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of global mortality, with acute exacerbations of COPD (AECOPD) significantly increasing the disease's morbidity and mortality. Among the pathogens implicated in AECOPD, Pseudomonas aeruginosa (P. aeruginosa) is increasingly recognized as a major co-infecting bacterium. Despite its clinical importance, the molecular mechanisms and therapeutic targets underlying AECOPD with P. aeruginosa infection remain inadequately understood.

METHODS

We employed a multi-omics approach, integrating proteomic analyses of bronchoalveolar lavage fluid (BALF) and plasma with transcriptomic analysis of peripheral blood. A discovery cohort of 40 AECOPD with P. aeruginosa infection patients and 20 healthy controls was analyzed, followed by validation in an independent cohort of 20 patients and 10 controls. Differentially expressed proteins (DEPs) and genes (DEGs) were identified and subjected to protein-protein interaction (PPI) network analysis, weighted gene co-expression network analysis (WGCNA), and immune infiltration analysis. Molecular docking simulations were conducted to explore potential therapeutic agents.

RESULTS

Our integrative analysis identified key biomarkers, which played critical roles in oxidative stress and neutrophil extracellular trap (NET) formation, both of which were pivotal in the pathogenesis of AECOPD with P. aeruginosa infection. The combined analysis of BALF, plasma, and peripheral blood underscored the interplay between local lung changes and systemic immune responses. Functional enrichment analyses highlighted significant pathways related to bacterial defense, inflammation, and immune activation. Validation in an independent cohort confirmed the diagnostic value of three key proteins (AZU1, MPO, and RETN), with high area under the curve (AUC) values in ROC analyses. Molecular docking indicated strong binding affinities of these proteins with Pioglitazone and Rosiglitazone, suggesting potential therapeutic utility.

CONCLUSIONS

This study provides a comprehensive understanding of the molecular mechanisms underlying AECOPD with P. aeruginosa infection, highlighting the pivotal roles of oxidative stress and NET formation in disease progression. The identified biomarkers offer promising diagnostic and therapeutic targets. Our findings pave the way for novel strategies to improve outcomes for AECOPD patients with P. aeruginosa infection. While the study design limits our ability to establish causality, these results provide important insights that warrant further investigation, particularly through longitudinal studies, to confirm the specific contributions of P. aeruginosa in exacerbations.

CLINICAL TRIAL NUMBER

Not applicable.

Low-speed centrifugation based isolation and self-priming mediated chain extension based fluorescent quantification of Pseudomonasaeruginosa

Infections acquired at home and hospital are rather prevalent, and the incidence of these infections has been on the rise in recent years due to the growing elderly population. Infections caused by Pseudomonas aeruginosa (P. aeruginosa) pose a significant risk to human health and are prevalent among patients in hospitals and nursing homes. Consequently, it is imperative to devise an innovative and fluorescent method for analyzing P. aeruginosa to facilitate the early identification of home-acquired pneumonia. However, it is difficult to isolate and simultaneously quantify P. aeruginosa using most of the currently available methods. We present a novel platform that combines aptamer recognition-based aggregation of target bacteria with self-priming induced chain extension for signal amplification. This approach facilitates low-speed centrifugation-based isolation and simultaneous quantification of P. aeruginosa. The chain displacement procedure is incorporated for signal amplification, providing the approach with a broad detection range of six orders of magnitude and a low detection limit of 2.4 cfu/mL. In addition to its exceptional sensitivity, the method demonstrates commendable selectivity for the detection of P. aeruginosa, rendering it a viable instrument for identifying home-acquired pneumonia caused by P. aeruginosa and facilitating the early management of P. aeruginosa infections in the emergency department.

Novel Species-Specific Primers Enable Accurate Detection and Quantification of Pseudomonas aeruginosa via qPCR

Pseudomonas aeruginosa, a notable pathogen in nosocomial infections, also emerges as a significant and often underestimated foodborne pathogen, frequently identified in diverse food categories, including meat, milk, fruits, vegetables, and water. Its resilience, virulence, and ability to form biofilms necessitate the development of novel methods for early detection of its presence in food products. This study aims to identify, design, and validate specific genetic markers for P. aeruginosa detection through quantitative PCR (qPCR) analysis. In this study, 816 publicly available genome sequences of P. aeruginosa strains were compared to identify a conserved and specific gene encoding a hypothetical protein (WP_003109295.1) in P. aeruginosa DSM 50071. Primers targeting this gene region were designed and validated for their ability to detect P. aeruginosa using qPCR, demonstrating a high level of sensitivity and specificity for P. aeruginosa among various Pseudomonas species. Further validation through standard curve analysis using three different templates such as cloned DNA, genomic DNA, and cell suspension confirmed the exceptional sensitivity and specificity of the designed primers in quantifying P. aeruginosa via qPCR. Additionally, the on-site application of these primers was validated on P. aeruginosa-inoculated carrot samples, highlighting their reliability and accuracy. The proposed direct qPCR method offers substantial advantages for the rapid, simple, and specific detection of P. aeruginosa, enhancing the efficiency of diagnostic and monitoring processes for this pathogen in food and vegetable distribution systems.

Imide-based enones: A new scaffold that inhibits biofilm formation in Gram-negative pathogens

We prepared a series of enones containing different substituents as potential antibiofilm molecules. The design considered the structural features previously found in N-acylhomoserine lactones, but it replaced the labile furanone with different imides portions. After evaluation, some of the analogs inhibited 50 % or more the formation of the biofilm from P. aeruginosa or A. baumannii; moreover, substituents attached at the phenyl ring, the size of the enone as well as the type of imide seemed relevant for the selectivity against the tested pathogens. In the end, we performed a molecular docking study using the crystallized LasR to describe the main interactions of the ligand-receptor complex and propose a plausible mechanism of action.

DNA aptamers targeting P. aeruginosa RNAP

We present the first DNA aptamers designed to target the RNA polymerase (RNAP) of Pseudomonas aeruginosa. Utilizing SELEX, we identified and examined aptamers, among which the R2 aptamer demonstrated high specificity and significant binding affinity for RNAP. R2 effectively captured RNAP, making it suitable for protein tandem purification and coating applications. These results have revealed that aptamers are valuable tools for investigating P. aeruginosa RNAP.

Ciprofloxacin-Loaded Spray-Dried Lactose Particles: Formulation Optimization and Antibacterial Efficacy

Background/Objectives: Bacterial infections in the oral cavity and outer ear require effective and targeted drug delivery systems. This study details the production of drug-loaded lactose microparticles, with the aim of creating antibiotic formulations for ultimate use in combatting oral and outer ear bacterial infections. Methods: Lactose particles were prepared via spray drying and optimized with varying ciprofloxacin (cipro) loadings to maximize the drug content. The particles were characterized to evaluate their performance in terms of physicochemical properties, drug-loading efficiency, drug-release kinetics, and antibacterial activity. Results: The resulting particles exhibited spherical morphology, efficient cipro loading (in the range of 1.1-52.9% w/w) and rapid cipro release within 5 h (achieving 70-81% release). In addition, they demonstrated effective concentration-dependent antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa, with bacterial growth effectively inhibited for more than 24 h when particle concentrations reached the minimum inhibitory concentration. Conclusions: These findings highlight the potential of spray-dried cipro loaded lactose particles as an efficient approach for localized antibacterial treatment, offering a promising solution for managing bacterial infections in the oral cavity and outer ear.

Ubiquitin Ligases in Control: Regulating NLRP3 Inflammasome Activation

Ubiquitin ligases play pivotal roles in the regulation of NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, a critical process in innate immunity and inflammatory responses. This review explores the intricate mechanisms by which various E3 ubiquitin ligases exert both positive and negative influences on NLRP3 inflammasome activity through diverse post-translational modifications. Negative regulation of NLRP3 inflammasome assembly is mediated by several E3 ligases, including F-box and leucine-rich repeat protein 2 (FBXL2), tripartite motif-containing protein 31 (TRIM31), and Casitas B-lineage lymphoma b (Cbl-b), which induce K48-linked ubiquitination of NLRP3, targeting it for proteasomal degradation. Membrane-associated RING-CH 7 (MARCH7) similarly promotes K48-linked ubiquitination leading to autophagic degradation, while RING finger protein (RNF125) induces K63-linked ubiquitination to modulate NLRP3 function. Ariadne homolog 2 (ARIH2) targets the nucleotide-binding domain (NBD) domain of NLRP3, inhibiting its activation, and tripartite motif-containing protein (TRIM65) employs dual K48 and K63-linked ubiquitination to suppress inflammasome assembly. Conversely, Pellino2 exemplifies a positive regulator, promoting NLRP3 inflammasome activation through K63-linked ubiquitination. Additionally, ubiquitin ligases influence other components critical for inflammasome function. TNF receptor-associated factor 3 (TRAF3) mediates K63 polyubiquitination of apoptosis-associated speck-like protein containing a CARD (ASC), facilitating its degradation, while E3 ligases regulate caspase-1 activation and DEAH-box helicase 33 (DHX33)-NLRP3 complex formation through specific ubiquitination events. Beyond direct inflammasome regulation, ubiquitin ligases impact broader innate immune signaling pathways, modulating pattern-recognition receptor responses and dendritic cell maturation. Furthermore, they intricately control NOD1/NOD2 signaling through K63-linked polyubiquitination of receptor-interacting protein 2 (RIP2), crucial for nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we explore how various pathogens, including bacteria, viruses, and parasites, have evolved sophisticated strategies to hijack the host ubiquitination machinery, manipulating NLRP3 inflammasome activation to evade immune responses. This comprehensive analysis provides insights into the molecular mechanisms underlying inflammasome regulation and their implications for inflammatory diseases, offering potential avenues for therapeutic interventions targeting the NLRP3 inflammasome. In conclusion, ubiquitin ligases emerge as key regulators of NLRP3 inflammasome activation, exhibiting a complex array of functions that finely tune immune responses. Understanding these regulatory mechanisms not only sheds light on fundamental aspects of inflammation but also offers potential therapeutic avenues for inflammatory disorders and infectious diseases.

Luteolin inhibits inflammation and M1 macrophage polarization in the treatment of Pseudomonas aeruginosa-induced acute pneumonia through suppressing EGFR/PI3K/AKT/NF-κB and EGFR/ERK/AP-1 signaling pathways

BACKGROUND

The opportunistic pathogen Pseudomonas aeruginosa primarily causes infections in immunocompromised individuals. Luteolin, a natural flavonoid, is widely present in plants, which exerts various pharmacological activities, including anti-inflammatory and antimicrobial activities.

PURPOSE

This study aimed to explore the therapeutic efficacy of luteolin and the underlying molecular mechanisms in treating the P. aeruginosa-induced acute pneumonia.

METHODS

Network pharmacology was utilized to identify the core targets of luteolin for treating acute P. aeruginosa pneumonia. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed to dissect the potential effects of luteolin and the involved signaling pathways. Surface plasmon resonance (SPR) assay and molecular docking were employed for studying the binding affinities of luteolin with the key targets. Furthermore, we applied a mouse model of bacterial pneumonia for assessing the therapeutic effects of luteolin in vivo, and an in vitro infection model for specifically investigating the effects of luteolin on macrophages as well as the underlying mechanisms upon P. aeruginosa infection.

RESULTS

Network pharmacology identified TNF, IL-6, EGFR and AKT1 as the key targets of luteolin for treating acute P. aeruginosa pneumonia. Moreover, as revealed by GO and KEGG enrichment analysis, EGFR, MAPK and PI3K/AKT pathways were the potential pathways regulated the P. aeruginosa-induced inflammatory response. According to the in vivo results, luteolin effectively mitigated the P. aeruginosa-induced acute lung injury through reducing the pulmonary permeability, neutrophil infiltration, proinflammatory cytokine production (IL-1β, IL-6, TNF and MIP-2) and bacterial burden in lung tissues, which led to increased survival rate of mice. Furthermore, the luteolin-treated mice had diminished EGFR, PI3K, AKT, IκBα, NF-κB p65, ERK, c-Jun and c-Fos phosphorylation, down-regulated M1 macrophage marker levels (iNOS, CD86 and IL-1β) but up-regulated M2 macrophage marker levels (Ym1, CD206 and Arg1) in lung tissues. Consistently, the luteolin-pretreated macrophages exhibited reduced phosphorylation of these regulatory proteins, diminished proinflammatory cytokine production, and down-regulated expression of M1 macrophage markers, but up-regulated expression of IL-10 and M2 macrophage markers.

CONCLUSION

luteolin effectively suppressed the inflammatory responses and M1 macrophage polarization through inhibiting EGFR/PI3K/AKT/NF-κB and EGFR/ERK/AP-1 signaling pathways in the treatment of acute P. aeruginosa pneumonia. This study suggests that luteolin could be a promising candidate for development as a therapeutic agent for acute bacterial pneumonia.

Eucommia folium can be Prepared as a Tea with the Ability to Prevent and Treat Hyperuricaemia

The aim of this study was to investigate the antihyperuricaemic (HUA) effect of Eucommia folium after preparing a tea made from its leaves (abbreviated as DZ) which has the ability to prevent and treat HUA. In this study, a mouse HUA model was established via gavage of potassium oxonate and hypoxanthine, and this HUA model was treated with DZ to investigate the therapeutic effect of DZ on HUA. This study recruited 30 HUA volunteers, who drank 10 g of DZ daily for four consecutive weeks. The serum HUA levels of UA volunteers were measured once per week to observe the anti-HUA efficacy of DZ at the clinical level. Animal experiments have shown that DZ has therapeutic effects on HUA. DZ effectively reduces the levels of uric acid (UA), creatinine (Cr), and urea nitrogen (BUN) in the serum of HUA mice; decreases xanthine oxidase (XOD) activity in the serum; and alleviates damage to kidney tissues and glomeruli. Metabolomic analysis revealed that DZ affects multiple metabolites, such as orotidine, orotic acid, ureidosuccinic acid, 1-methylhistidine, and other metabolites, and these metabolites are involved mainly in pyrimidine metabolism, histidine metabolism, and riboflavin metabolism. Clinical research revealed that, after DZ was consumed, the UA levels in the HUA volunteers significantly decreased. Our research findings suggest that DZ may have a protective effect against HUA. and is in the same class of traditional Chinese medicines used in medicine and food, with extremely low toxicity and high safety. Therefore, DZ may be suitable for preparation as a functional food with anti HUA effects. CLINICAL TRIAL NUMBER: Not applicable.

Development and Characterization of LasR Immobilized Monolithic Column for Screening Active Ingredients as Quorum Sensing Inhibitors Against P. aeruginosa in Natural Products

Background and Aim

The enzyme/protein immobilized monolithic capillary combined with liquid chromatography-mass spectrometry is an efficient screening strategy for the corresponding agonist/antagonist. LasR is the potential therapeutic target since it plays a vital role in the colonization and invasion of Pseudomonas aeruginosa (P. aeruginosa). Therefore, reagents that inhibit LasR may be effective against P. aeruginosa. To screen and find LasR inhibitors rapidly, a LasR-immobilized monolithic capillary column was prepared and characterized.

Methods

Firstly, the recombinant LasR protein was prepared in E. coli. Then, the LasR protein was immobilized to the surface of poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine monolithic column. The affinity and stability of prepared column was also evaluated. Furthermore, the prepared column was applied to fishing LasR inhibitor in Scutellaria baicalensis Georgi extract. The interaction of the screening compound to LasR was confirmed through molecular docking.

Results

The recombinant active LasR protein was prepared in E. coli. After purification and validation, a comparative ligand fishing monolithic column was prepared through immobilizing LasR to the surface of the poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine through amidation reaction. The LasR was successfully immobilized to the monolithic column characterizing by Fourier transform infrared spectroscopy and scanning electron microscopy. The activity of immobilized LasR was reserved as it has affinity to the nature ligand 3-oxo-C12-HSL and stablied within 24 h at 4 °C. In the Scutellaria baicalensis Georgi extract, baicalein was screened as a potential LasR inhibitor. The molecular docking results and the in vivo evaluation confirmed the activity of baicalein.

Conclusion

The proposed LasR immobilized monolithic column is a viable strategy in screening LasR inhibitors. It can be considered as a possible alternative to traditional methods for screening LasR inhibitors as drug candidates against P. aeruginosa.

Dendrobium huoshanense C. Z. Tang and S. J. Cheng can be prepared as a food with the ability to prevent and treat hyperuricaemia

Background

Hyperuricemia (HUA) is the presence of excessive uric acid (UA) in blood, which leads to an increased risk of chronic kidney disease and gout. There are about 120 million hyperuricemia patients in China, which has surpassed diabetes as the second largest chronic disease.

Objective

The aim of the present study was to investigate the hypouricemic effects of Dendrobium huoshanense C. Z. Tang and S. J. Cheng (DH), and provide a basis for its development into anti HUA products.

Methods

This study established a mouse HUA model by gavage of potassium oxonate (PIO) and hypoxanthine (HX), and treated with DH to investigate the therapeutic effect of DH on hyperuricemia. Use a biochemical assay kit to detect changes in the levels of UA, creatinine (Cr), and urea nitrogen (BUN) in mouse serum; Use ELISA kit to detect the activity of xanthine oxidase (XOD) in serum; Untargeted Metabolomics analysis was performed on the serum of each group of mice using liquid chromatography-mass spectrometry. This study recruited 23 HUA volunteers, volunteers drank 0.5 g DH daily for four consecutive weeks, with serum UA levels measured once a week.

Results

Animal experiments have shown that DH has therapeutic effects on HUA, mainly manifested as: DH effectively reduces the levels of UA, Cr, and BUN in the serum of HUA mice, lowers XOD activity in the serum, and alleviates kidney tissue and glomerular damage. Metabolomics analysis showed that there were 306 significant differences in metabolites between the Sham group, HUA model group, and DH group. Pathway analysis of these differential metabolites revealed that they were mainly involved in pyrimidine metabolism, histidine metabolism, and riboflavin metabolism. Clinical research results show that after drinking DH, UA levels in HUA volunteers significantly decreased, and most HUA volunteers' UA levels decreased to normal levels.

Conclusion

DH has the effect of preventing and treating hyperuricemia, and it belongs to the same class of traditional Chinese medicine as medicine and food, with extremely low toxicity and high safety. Therefore, DH is suitable for preparation as a product for preventing and treating HUA in functional food and other products.

Aspirin enhances the antibacterial activity of colistin against multidrug-resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) Pseudomonas aeruginosa (PSA), recently reclassified by the World Health Organization (WHO) as a high-priority antimicrobial-resistant pathogen, continues to impose a substantial global health burden due to escalating resistance and stagnant therapeutic innovation. Colistin retains critical clinical utility against MDR P. aeruginosa infections; however, its dose-limiting nephrotoxicity and neurotoxicity necessitate strategies to optimise therapeutic indices. This study investigated the molecular mechanism underlying the synergistic activity of aspirin in potentiating colistin efficacy against MDR P. aeruginosa. In vitro analyses revealed marked synergistic bactericidal activity (FIC index ≤0.5), with metabolomic profiling demonstrating suppression of key metabolic pathways integral to bacterial membrane biogenesis, including glycerophospholipid metabolism and fatty acid biosynthesis. Ultrastructural imaging confirmed irreversible disruption of membrane integrity via combined treatment. In a rat model of P. aeruginosa-induced pneumonia, colistin-aspirin co-administration demonstrated superior efficacy to monotherapy, significantly reducing pulmonary bacterial load (3 to 4-log CFU/g reduction vs colistin alone; p < 0.01), attenuating histopathological injury, and suppressing pro-inflammatory cytokine levels (IL-6, IL-8, TNF-α) by 30-47%. Critically, this synergy enabled a reduction of colistin dosing to one-sixteenth while maintaining bactericidal potency. These findings provide mechanistic insights into aspirin-mediated colistin sensitisation and evidence supporting combinatorial regimens to circumvent colistin toxicity barriers. This work establishes a rational foundation for clinical translation of repurposed aspirin-colistin therapy against MDR P. aeruginosa infections.

Chronic suppurative otitis media: disrupted host-microbial interactions and immune dysregulation

Recent research has uncovered new mechanisms that disrupt the balance between the host and microbes in the middle ear, potentially leading to dysbiosis and chronic suppurative otitis media (CSOM). Dysbiotic microbial communities, including core pathogens such as persister cells, are recognized for displaying cooperative virulence. These microbial communities not only evade the host's immune defenses but also promote inflammation that leads to tissue damage. This leads to uncontrolled disorder and pathogen proliferation, potentially causing hearing loss and systemic complications. In this discussion, we examine emerging paradigms in the study of CSOM that could provide insights into other polymicrobial inflammatory diseases. Additionally, we underscore critical knowledge gaps essential for developing a comprehensive understanding of how microbes interact with both the innate and adaptive immune systems to trigger and maintain CSOM.

Microbiota shifts in fracture-related infections and pathogenic transitions identified by 16S rDNA sequencing

Fracture-related infection (FRI) is a major challenge in orthopaedic trauma. Understanding of the microbial shift with respect to the initial contamination to infection phase is crucial. This study was to examine the wound microbiota associated with FRI in a prospective cohort study of 155 patients with Gustilo-Anderson Type II, IIIA or IIIB open fractures. Tissue samples were systematically collected from all patients during initial surgical debridement. Out of these, patients who developed infection (FRI group, n = 28) had a second tissue sampling during re-debridement. Conversely, patients who achieved normal healing and subsequently received definitive open reduction and internal fixation served as control (NH group, n = 24). Marked differences between all groups were revealed in the 16S rDNA analysis of microbial communities. The species richness was higher in the Pre-FRI group, but bacterial diversity declined significantly in the FRI group after infection onset. In the Pre-FRI and Pre-NH groups, Firmicutes were the dominating phylum, while in the FRI and NH groups, Proteobacteria and Actinobacteria appeared more prevalent, respectively. In Pre-FRI notably abundant Bacillus and Staphylococcus and in FRI, the most pathogens were Enterobacter and Pseudomonas. The NH group maintained balanced microbial diversity. These findings suggest that declining microbiota diversity and shifts towards dominant pathogens in open fracture patients may serve as early indicators of infection risk, with Bacillus potentially emerging as a predictive biomarker for FRI susceptibility.

Revitalizing Antibiotics with Macromolecular Engineering: Tackling Gram-Negative Superbugs and Mixed Species Bacterial Biofilm Infections In Vivo

The escalating prevalence of multidrug-resistant Gram-negative pathogens, coupled with dwindling antibiotic development, has created a critical void in the clinical pipeline. This alarming issue is exacerbated by the formation of biofilms by these superbugs and their frequent coexistence in mixed-species biofilms, conferring extreme antibiotic tolerance. Herein, we present an amphiphilic cationic macromolecule, ACM-AHex, as an innovative antibiotic adjuvant to rejuvenate and repurpose resistant antibiotics, for instance, rifampicin, fusidic acid, erythromycin, and chloramphenicol. ACM-AHex mildly perturbs the bacterial membrane, enhancing antibiotic permeability, hampers efflux machinery, and produces reactive oxygen species, resulting in a remarkable 64-1024-fold potentiation in antibacterial activity. The macromolecule reduces bacterial virulence and macromolecule-drug cocktail significantly eradicate both mono- and multispecies bacterial biofilms, achieving >99.9% bacterial reduction in the murine biofilm infection model. Demonstrating potent biocompatibility across multiple administration routes, ACM-AHex offers a promising strategy to restore obsolete antibiotics and combat recalcitrant Gram-negative biofilm-associated infections, advocating for further clinical evaluation as a next-generation macromolecular antibiotic adjuvant.

Inhibiting NLRP3 enhances cellular autophagy induced by outer membrane vesicles from Pseudomonas aeruginosa

The bacterium Pseudomonas aeruginosa is able to invade lung epithelial cells and survive intracellularly. During this process, it secretes outer membrane vesicles (OMVs), however, it is currently unclear how OMVs from P. aeruginosa (PA-OMVs) affect lung epithelial cells and their impact on oxidative stress, autophagy, and other physiological activities of lung epithelial cells. In this study, we found that PA-OMVs activated oxidative stress and autophagy in cells. We demonstrated that the NLRP3 (NLR family, pyrin domain containing 3) inhibitor MCC950 can enhance autophagy induced by PA-OMVs. The main function of NLRP3 is related to the body's immune response and inflammation regulation. MCC950 is the most common inhibitor of NLRP3. Additionally, we showed that PA-OMVs not only enhanced the expression of AMP-activated protein kinase, a key regulator of cellular energy homeostasis, and reactive oxygen species, which play a crucial role in cellular signaling and oxidative stress, but also significantly enhanced the expression of NLRP3. Inhibiting the expression of NLRP3 further enhanced the process of PA-OMVs induced autophagy. These results demonstrate that PA-OMVs activate both autophagy and the NLRP3 inflammasome, with NLRP3 suppressing autophagy to a certain extent, hoping to provide broad ideas for the future applications of PA-OMVs.IMPORTANCEThe discovery that lung epithelial cells exposed to outer membrane vesicles from Pseudomonas aeruginosa (PA-OMVs) activate cellular autophagy and induce protective immunity is significant. Specifically, the addition of an NLRP3 inhibitor, MCC950, has been found to decrease NLRP3 targets while simultaneously enhancing the autophagy activity induced by PA-OMVs. This finding unveils a novel theoretical framework for the development of PA-OMVs vaccines, highlighting new targets for enhancing the body's anti-infective responses. By elucidating the mechanisms through which PA-OMVs trigger autophagy and bolster immune defenses, this research opens avenues for innovative vaccine design strategies aimed at combatting infections effectively.

Phage-host interaction in Pseudomonas aeruginosa clinical isolates with functional and altered quorum sensing systems

Quorum sensing (QS) plays a crucial role in regulating key traits, including the upregulation of phage receptors, which leads to heightened phage susceptibility in Pseudomonas aeruginosa. As a result, higher cell densities typically increase the risk of phage invasions. This has led to speculation that bacteria may have evolved strategies to counterbalance this increased susceptibility. Additionally, non-synonymous mutations in LasR, the master regulator of QS, are common among cystic fibrosis patients, but the impact of these mutations on phage interactions remains poorly understood. Here, we systematically investigated the role of QS in shaping these interactions using bacterial strains with functional or altered QS systems. In the QS-functional strain ZS-PA-35, disruption of the Las system reduces cell susceptibility to the type IV pili-dependent phage phipa2, delaying bacterial lysis during the early logarithmic growth phase. At high cell densities, Las-induced dormancy further inhibits phage proliferation despite enhanced phage adsorption. Notably, nutrient supplementation fully restores phage proliferation in the strains with a functional Las system. In contrast, the QS-deficient strain ZS-PA-05, carrying a LasR mutation, fails to regulate phage-host interactions via QS. Moreover, our findings reveal that within mixed microbial populations, cells benefit from the presence of closely related kin, which collectively reduce prey density and limit phage-host interaction frequencies under nutrient-rich conditions. These results underscore the flexibility of QS-regulated defense strategies, highlighting their critical role in optimizing bacterial resilience against phage predation, particularly in heterogeneous communities most vulnerable to phages.IMPORTANCEBacteria have developed various strategies to combat phage infection, posing challenges to phage therapy. In this study, we demonstrate that Pseudomonas aeruginosa strains with functional or altered quorum sensing (QS) systems may adapt different survival tactics for prolonged coexistence with phages, contingent upon bacterial population dynamics. The dynamics of phage infection highlight the influence of intrinsic heterogeneity mediated by QS, which leads to the emergence of different phage-host outcomes. These variants may arise as a result of coevolutionary processes or coexistence mechanisms of mutational and non-mutational defense strategies. These insights enhance our comprehension of how bacteria shield themselves against phage attacks and further underscore the complexity of such approaches for successful therapeutic interventions.

Advancements in Escherichia coli secretion systems for enhanced recombinant protein production

Escherichia coli is inarguably one of the most studied microorganisms across the spectrum of microbiology. It is very widely used in recombinant protein production owing to its rapid growth, ease of genetic manipulation, and relatively high protein yields. Despite all of its advantages, its inability to efficiently secrete proteins naturally remains a drawback leading to protein aggregation as inclusion bodies in the cytoplasm and consequent low overall protein yield. Therefore, many approaches to mitigate this weakness and enhance extracellular secretion to increase protein yield have been devised. This review explores the natural and engineered secretion systems in E. coli, highlighting their potential for enhanced protein secretion for non-glycosylated proteins. Natural one-step (e.g., Type I and III Secretion Systems) and two-step systems (e.g., Sec and Tat pathways) are detailed alongside recent advancements in genetic engineering, mutagenesis, and synthetic biology approaches aimed at improving protein yield, folding, and secretion efficiency. Emerging technologies, such as the ESETEC® and BacSec® platforms, promise scalable and cost-effective solutions for higher protein production. Challenges, including limited cellular capabilities and protein aggregation, are addressed through innovative strategies like cell wall modification, co-expression of chaperones, and medium optimization. This review emphasizes E. coli's adaptability to industrial applications, and the promising future of recombinant protein technologies.

Two amino-substituted diphenyl fumaramide derivatives inhibit the virulence regulated by quorum sensing system of Pseudomonas aeruginosa

AIM

Pseudomonas aeruginosa employs the quorum sensing (QS) system, a sophisticated cell-to-cell communication mechanism, to modulate the synthesis and secretion of a range of virulence factors, which contribute to the establishment of acute or chronic infections in hosts. This study seeks to attenuate the virulence of P. aeruginosa by inhibiting the QS system, thereby reducing its pathogenicity as a promising alternative to traditional antibiotics.

METHODS AND RESULTS

Two compounds with an amino-substituted diphenyl fumaramide core, N1-(4-bromophenyl)-N4-(4'-oxo-3',4'-dihydro-1'H-spiro [cyclopentane-1,2'-quinazolin]-6'-yl) fumaramide (10D) and N1-(3-chloro-4-fluorophenyl)-N4-(4-oxo-3,4,4',5'-tetrahydro-1H,2'H-spiro [quinazoline-2,3'-thiophen]-6-yl) fumaramide (12A), were identified through in-silico screening. The QS inhibitory potential of both compounds was explored in vitro and in vivo. In in vitro experiments, neither compound exhibited bactericidal effects but significantly inhibited the production of QS-regulated extracellular protease and pyocyanin. Quantitative PCR analysis revealed that QS-activated genes and downstream virulence genes were transcriptionally suppressed by 10D or 12A. Molecular docking and molecular dynamics simulations predicted stable interactions between these compounds and the key QS regulators LasR and PqsR. When combined with polymyxin B, kanamycin, and levofloxacin, 10D and 12A exhibited synergistic antibacterial activity. Furthermore, compounds 10D and 12A significantly improved the survival of mice challenged with P. aeruginosa and effectively reduced the bacterial load in the lungs.

CONCLUSION

This study indicates that 10D and 12A possess considerable QS inhibitory potential, effectively attenuating the pathogenicity of P. aeruginosa. Moreover, the study offers structural insights and methodological guidance for the advancement of anti-virulence drug development.

In-vitro activity of the novel β-lactam/β-lactamase inhibitor combinations and cefiderocol against carbapenem-resistant Pseudomonas spp. clinical isolates collected in Switzerland in 2022

To evaluate the in-vitro activity of the novel commercially-available drugs, including meropenem-vaborbactam (MEV), ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), imipenem-relebactam (IPR) as well as cefiderocol (FDC), against carbapenem-resistant Pseudomonas spp. (CRP) isolates. All CRP isolates collected at the Swiss National Reference Laboratory (NARA) over the year 2022 (n = 170) have been included. Most of these isolates (n = 121) were non-carbapenemase producers. Among the 49 carbapenemase producers, 47 isolates produced metallo-β-lactamases (MBL) including NDM-1 (n = 11), VIM-like (n = 28), IMP-like (n = 7), and both NDM-1 and VIM-2 (n = 1) and two isolates produced the class A carbapenemase GES-5. Susceptibility testing was determined by broth microdilution method (BMD), or disk diffusion test, and results interpreted following EUCAST guidelines. The susceptibility rates for MEV, CZA, C/T and IPR were found to be 41%, 45%, 59% and 58%, respectively, for the whole set of isolates tested. Among non-carbapenemase producers, susceptibility rates for these β-lactam/β-lactamase inhibitors (BL/BLI) combinations were higher, determined at 55%, 61%, 83%, and 82%, respectively. The overall susceptibility of carbapenemase-producing Pseudomonas spp. to novel BL/BLI was relatively low, while 80% of these isolates demonstrated susceptibility to FDC, with a similar proportion (79%) observed among MBL producers. A total of 10 MBL-producing isolates (6%), mainly NDM-1, were found to exhibit resistance to all drugs tested, with the exception of colistin. FDC exhibited an excellent in-vitro activity against this collection of CRP recovered from Switzerland in 2022, including MBL producers. The new BL/BLI combinations displayed significant activity against non-carbapenemase CRP, with IPR and C/T showing the highest susceptibility rates.

Sputum metagenomics reveals a multidrug resistant Pseudomonas-dominant severe asthma phenotype in an Asian population

BACKGROUND AND OBJECTIVE

While the lung microbiome in severe asthma has been studied, work has employed targeted amplicon-based sequencing approaches without functional assessment with none focused on multi-ethnic Asian populations. Here we investigate the clinical relevance of microbial phenotypes of severe asthma in Asians using metagenomics.

METHODS

Prospective assessment of clinical, radiological, and immunological measures were performed in a multi-ethnic Asian severe asthma cohort (N = 70) recruited across two centres in Singapore. Sputum was subjected to shotgun metagenomic sequencing and patients followed up for a 2-year period. Metagenomic assessment of sputum microbiomes, resistomes and virulomes were related to clinical outcomes.

RESULTS

The lung microbiome in a multi-ethnic Asian cohort with severe asthma demonstrates an increased abundance of Pseudomonas species. Unsupervised clustering of sputum metagenomes identified two patient clusters: C1 (n = 52) characterized by upper airway commensals and C2 (n = 18) dominated by established respiratory pathogens including M. catarrhalis, S. aureus and most significantly P. aeruginosa. C2 patients demonstrated a significantly increased exacerbation frequency on 2-year follow up and an antimicrobial resistome characterized by multidrug resistance. Virulomes appear indistinguishable between severe asthmatics with or without co-existing bronchiectasis, and C2 patients exhibit increased gene expression related to biofilm formation, effector delivery systems and microbial motility. Independent comparison of the C2 cluster to a non-asthmatic bronchiectasis cohort demonstrates analogous airway microbial virulence patterns.

CONCLUSION

Sputum metagenomics demonstrates a multidrug-resistant Pseudomonas-dominant severe asthma phenotype in Asians, characterized by poor clinical outcome including increased exacerbations which is independent of co-existing bronchiectasis.

Targeting Pseudomonas aeruginosa PAO1 pathogenicity: The role of Glycyrrhiza glabra in inhibiting virulence factors and biofilms

Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative opportunistic pathogen posing serious risks to immunocompromised individuals due to its virulence factors and biofilm formation. This study evaluated the efficacy of methanol extract of Glycyrrhiza glabra (G. glabra) in mitigating P. aeruginosa PAO1 pathogenesis through in-vitro assays, including Minimum Inhibitory Concentration (MIC), biofilm assay, growth curve analysis, pyocyanin quantification, and molecular docking. The extract inhibited PAO1 growth at 5 mg/mL and demonstrated significant antibiofilm activity at sub-MIC levels, reducing biofilm formation by 50.22 %, 22.13 %, and 11.53 % at concentrations of 1.25 mg/mL, 0.625 mg/mL, and 0.312 mg/mL, respectively. Pyocyanin production was also significantly suppressed. Molecular docking revealed that 4-(4-Trifluoromethyl-benzoylamino)-benzoic acid and betulinic acid, identified in the extract, exhibited strong binding affinities (-6.4 kcal/mol and -6.9 kcal/mol) to the QS regulator 7XNJ. These findings underscore the potential of G. glabra as an antipathogenic agent against P. aeruginosa, warranting further investigation into its clinical applications.

Pollution profiles, pathogenicity, and toxicity of bioaerosols in the atmospheric environment of urban general hospital in China

Airborne microorganisms in hospitals present significant health risks to both patients and employees. However, their pollution profiles and associated hazards in different hospital areas remained largely unknown during the extensive use of masks and disinfectants. This study investigated the characteristics of bioaerosols in an urban general hospital during the COVID-19 pandemic and found that airborne bacteria and fungi concentrations range from 87 ± 35 to 1037 ± 275 CFU/m3 and 21 ± 15 to 561 ± 132 CFU/m3, respectively, with the outpatient clinic and internal medicine ward showing the highest levels. The operating room (OR) and clinical laboratory (LA) had lower bioaerosol levels but higher microbial activities, suggesting that disinfection procedures used to clean bioaerosols may change them into a viable but non-culturable state. The dominant fungi were Cladosporium, Aspergillus, and Penicillium, while the most common viruses were human associated gemykibivirus 2 and human alpha herpesvirus 1. Besides, the dominant pathogens were Staphylococcus aureus, Salmonella enterica, and Pseudomonas aeruginosa. Bacitracin and macrolides resistance genes bacA and ermC were the most prevalent subtypes of antibiotic resistance genes. Compared to the control sample, hospital-acquired bioaerosols, particularly from the outpatient examination room and emergency room can trigger higher levels of inflammatory factors and cell toxicity but lower cell proliferation rates. Lower cell toxicity was observed in low-risk areas (intensive care unit, LA, and OR). This study provides a new method for assessing bioaerosol health risks and enhances understanding of nosocomial and opportunistic infections and their control.

Novel antimicrobial strategies for diabetic foot infections: addressing challenges and resistance

AIMS

This review examines the challenges posed by Diabetic Foot Infections (DFIs), focusing on the impact of neuropathy, peripheral arterial disease, immunopathy, and the polymicrobial nature of these infections. The aim is to explore the factors contributing to antimicrobial resistance and assess the potential of novel antimicrobial treatments and drug delivery systems in improving patient outcomes.

METHOD

A comprehensive analysis of existing literature on DFIs was conducted, highlighting the multifactorial pathogenesis and polymicrobial composition of these infections. The review delves into the rise of antimicrobial resistance due to the overuse of antimicrobials, biofilm formation, and microbial genetic adaptability. Additionally, it considers glycemic control, patient adherence, and recurrence rates as contributing factors to treatment failure. Emerging therapies, including new antimicrobial classes and innovative drug delivery systems, were evaluated for their potential efficacy.

RESULTS

DFIs present unique treatment challenges, with high rates of antimicrobial resistance and poor response to standard therapies. Biofilm formation and the genetic adaptability of pathogens worsen resistance, complicating treatment. Current antimicrobial therapies are further hindered by poor glycemic control and patient adherence, leading to recurrent infections. Novel antimicrobial classes and innovative delivery systems show promise in addressing these challenges by offering more targeted, effective treatments. These new approaches aim to reduce resistance and improve treatment outcomes.

CONCLUSION

DFIs remain a clinical challenge due to their multifactorial nature and antimicrobial resistance. The development of novel antimicrobials and drug delivery systems is crucial to improving patient outcomes and combating resistance. Future research should focus on enhancing treatment efficacy, reducing resistance, and addressing patient adherence to reduce the burden of DFIs.

Antibiotic resistance genes and virulence factors in the plastisphere in wastewater treatment plant effluent: Health risk quantification and driving mechanism interpretation

Microplastics (MPs) are ubiquitous in wastewater treatment plants (WWTPs) and provide a unique niche for the spread of pollutants. To date, risk assessments and driving mechanisms of pathogens, antibiotic resistance genes (ARGs), and virulence factors (VFs) in the plastisphere are still lacking. Here, the microbiota, ARGs, VFs, their potential health risks, and biologically driving mechanisms on polythene (PE), polyethylene terephthalate (PET), poly (butyleneadipate-co-terephthalate) and polylactic acid blends (PBAT/PLA), PLA MPs, and gravel in WWTP effluent were investigated. The results showed that plastisphere and gravel biofilm harbored more distinctive microorganisms, promoting the uniqueness of pathogens, ARGs, and VFs compared to WWTP effluent. The abundance of major pathogens, ARGs, and VFs in the plastisphere was 1.01-1.35 times higher than that in the effluent. The high health risk of ARGs (HRA) calculated by fully considering the abundance, clinical relevance, pathogenicity, accessibility and mobility, and the high proportion of resistance contigs with mobile genetic elements confirmed that the plastisphere posed the highest potential health risk. Candidatus Microthrix and Candidatus Promineifilum were the essential hosts of ARGs and VFs in the plastisphere and gravel biofilm, respectively. High metabolic activity such as amino acid metabolism and biosynthesis of secondary metabolites, and highly expressed key genes increased the synthesis of ARGs and VFs. The primary mechanisms driving ARG enrichment in the plastisphere were enhanced microbial metabolic activity, increased frequency of horizontal gene transfer, heightened antibiotic inactivation and efflux, and reduced cell permeability. This study provided new insights into the ARGs, VFs, and health risks of the plastisphere and emphasized the importance of strict control of wastewater discharge.

Novel therapeutic strategy: Nrf2 activation in targeting senescence-related changes in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide, largely driven by the accumulation of senescent bronchial epithelial cells, which contribute to inflammation and tissue remodeling. This study investigates the therapeutic potential of nuclear factor erythroid 2-related factor 2 (Nrf2) activation in targeting senescence-related changes to alleviate COPD progression.

Methods

Single-cell transcriptome analysis, in vitro COPD cell models, and a COPD mouse model were utilized to examine the effects of Nrf2 activation. Specifically, the study focused on the impact of Nrf2 on senescent ciliated epithelial cells and the associated secretory phenotype. Respiratory function tests and lung pathology assessments were conducted to evaluate the intervention's efficacy in the mouse model.

Results

The study identified a significant presence of senescent ciliated epithelial cells in COPD patients, contributing to disease progression. Nrf2 activation in vitro reduced senescence markers, enhanced cell proliferation, and decreased inflammatory cytokines. In vivo, Nrf2 activation significantly improved lung function and reduced pathological damage in the COPD mouse model.

Conclusions

The findings underscore the potential of Nrf2 activation as a therapeutic strategy to mitigate COPD progression by modulating the senescence-associated secretory phenotype (SASP). This study suggests that Nrf2 activators could offer a promising approach to improving clinical outcomes for COPD patients.

Design, Synthesis, and Biological Evaluation of Asymmetrical Disulfides Based on Garlic Extract as Pseudomonas aeruginosa pqs Quorum Sensing Inhibitors

Pseudomonas aeruginosa is a widely encountered bacterium linked to the deterioration of food products and represents a notable concern for public health safety. Disulfides serve as significant pharmacologically active scaffolds exhibiting antibacterial, antiviral, and anticancer properties; however, reports on their activity as quorum sensing inhibitors (QSIs) against P. aeruginosa are limited. In our work, asymmetrical disulfides were designed and synthesized, utilizing natural products, such as allicin, ajoene, diallyl disulfide (DADS), hordenine, and cinnamic acid, as lead compounds. By screening for lasB, rhlA, and pqsA promoter activity, two highly effective QSIs were identified. Compounds 7d and 4c show effectiveness in reducing the synthesis of different virulence factors, the creation of biofilms, and movement capabilities. Subsequent validation using the Galleria mellonella larvae model confirmed their robust in vivo efficacy. Moreover, their combination with antibiotics markedly augmented the antibacterial activity. Mechanism studies employed by transcriptome analysis, quantitative reverse transcription-PCR (qRT-PCR), surface plasmon resonance, and molecular docking demonstrate that compound 7d disrupts the quorum sensing system by interacting with PqsR. These findings suggest that our disulfide derivatives hold promise for treating P. aeruginosa infections.

High prevalence of carbapenem-resistant Pseudomonas aeruginosa and identification of a novel VIM-type metallo-β-lactamase, VIM-92, in clinical isolates from northern China

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) has become a serious global health concern due to the limited treatment options. The primary resistance mechanism in CRPA involves the production of metallo-β-lactamases (MBLs), making MBL-producing P. aeruginosa a significant component of CRPA cases. To understand the prevalence of CRPA in hospitals in northern China, we conducted a preliminary screening and identification of CRPA in 143 clinical isolates of P. aeruginosa collected from various departments of a tertiary hospital between 2021 and 2023, analyzing CRPA resistance trends in certain regions of northern China during this period. We identified 71 CRPA isolates that exhibited high carbapenem resistance and phylogenetic tree analysis revealed that ST244 CRPA isolates had widely spread across various departments of the same hospital over three consecutive years. We also identified two VIM-producing isolates, PJK40 and PJK43, both of which carried the same novel VIM-type metallo-β-lactamase, VIM-92, encoded by a newly identified gene, bla VIM-92, closely related to bla VIM-24. bla VIM-92 was embedded in class 1 integrons within the Tn1403 transposon. The bla VIM-92-carrying plasmid, pPJK40, was found to resemble the pJB37 megaplasmid. The expression of VIM-92 and VIM-24 in DH5α and PAO1 revealed similar effects of the MICs of β-lactams, except for aztreonam. The high prevalence of CRPA in clinical settings, and the identification of VIM-92, highlights the urgent need for ongoing surveillance of CRPA and emerging MBL variants in P. aeruginosa.

A VgrG2b fragment cleaved by caspase-11/4 promotes Pseudomonas aeruginosa infection through suppressing the NLRP3 inflammasome

The T6SS of Pseudomonas aeruginosa plays an essential role in the establishment of chronic infections. Inflammasome-mediated inflammatory cytokines are crucial for host defense against bacterial infections. We found that P. aeruginosa infection activates the non-canonical inflammasome in macrophages, yet it inhibits the downstream activation of the NLRP3 inflammasome. The VgrG2b of P. aeruginosa is recognized and cleaved by caspase-11, generating a free C-terminal fragment. The VgrG2b C-terminus can bind to NLRP3, inhibiting the activation of the NLRP3 inflammasome by rejecting NEK7 binding to NLRP3. Administration of a specific peptide that inhibits caspase-11 cleavage of VgrG2b significantly improves mouse survival during infection. Our discovery elucidates a mechanism by which P. aeruginosa inhibits host immune response, providing a new approach for the future clinical treatment of P. aeruginosa infections.

Kaempferol Mitigates Pseudomonas aeruginosa-Induced Acute Lung Inflammation Through Suppressing GSK3β/JNK/c-Jun Signaling Pathway and NF-κB Activation

Background: Pseudomonas aeruginosa, one of the common bacterial pathogens causing nosocomial pneumonia, is characterized as highly pathogenic and multidrug-resistant. Kaempferol (KP), a natural flavonoid, has been shown to exhibit effectiveness in treating infection-induced lung injury. Methods: We applied network pharmacology to explore the underlying mechanisms of KP in treating P. aeruginosa pneumonia and further validated them through a mouse model of acute bacterial lung infection and an in vitro macrophage infection model. Results: The in vivo studies demonstrated that treatment with KP suppressed the production of proinflammatory cytokines, including TNF, IL-1β, IL-6, and MIP-2, and attenuated the neutrophil infiltration and lesions in lungs, leading to an increased survival rate of mice. Further studies revealed that KP treatment enhanced the phosphorylation of GSK3β at Ser9 and diminished the phosphorylation of JNK, c-Jun, and NF-κB p65 in lungs in comparison to the mice without drug treatment. Consistently, the in vitro studies showed that pretreatment with KP reduced the activation of GSK3β, JNK, c-Jun, and NF-κB p65 and decreased the levels of the proinflammatory cytokines in macrophages during P. aeruginosa infection. Conclusions: KP reduced the production of proinflammatory cytokines by inhibiting GSK3β/JNK/c-Jun signaling pathways and NF-κB activation, which effectively mitigated the P. aeruginosa-induced acute lung inflammation and injury, and elevated the survival rates of mice.

Snapshots of Pseudomonas aeruginosa SOS response reveal structural requisites for LexA autoproteolysis

Antimicrobial resistance poses a severe threat to human health and Pseudomonas aeruginosa stands out among the pathogens responsible for this emergency. The SOS response to DNA damage is crucial in bacterial evolution, influencing resistance development and adaptability in challenging environments, especially under antibiotic exposure. Recombinase A (RecA) and the transcriptional repressor LexA are the key players that orchestrate this process, determining either the silencing or the active transcription of the genes under their control. By integrating state-of-the-art structural approaches with in vitro binding and functional assays, we elucidated the molecular events activating the SOS response in P. aeruginosa, focusing on the RecA-LexA interaction. Our findings identify the conserved determinants and strength of the interactions that allow RecA to trigger LexA autocleavage and inactivation. These results provide the groundwork for designing novel antimicrobial strategies and exploring the potential translation of Escherichia coli-derived approaches, to address the implications of P. aeruginosa infections.

Pseudomonas aeruginosa aggregates elicit neutrophil swarming

Pseudomonas aeruginosa, a gram-negative multidrug-resistant (MDR) opportunist, belongs to the ESKAPE group of pathogens associated with the highest risk of mortality. Neutrophil swarming is a host defense strategy triggered by larger threats, where neutrophil swarms contain and clear damage/infection. Current ex vivo models designed to study neutrophil-pathogen interactions largely focus on individual neutrophil engagement with bacteria and fail to capture neutrophil swarming. Here, we report an ex vivo model that reproducibly elicits neutrophil swarming in response to bacterial aggregates. A rapid and robust swarming response follows engagement with pathogenic targets. Components of the type III secretion system (T3SS), a critical P. aeruginosa virulence determinant, are involved in swarm interaction. This ex vivo approach for studying neutrophil swarming in response to large pathogen targets constitutes a valuable tool for elucidating host-pathogen interaction mechanisms and for evaluating novel therapeutics to combat MDR infections.

The virulence trait and genotype distribution amongst the Pseudomonas aeruginosa clinical strains

BACKGROUND

Pseudomonas aeruginosa is notorious for its complex virulence system and rapid adaptive drug resistance. This study aimed to compare the prevalence and genotype distribution of virulence genes in multidrug-sensitive and multidrug-resistant clinical strains of Pseudomonas aeruginosa. It is possible to better understand the genetic characteristics of Pseudomonas aeruginosa and carry out effective treatment and prevention measures.

METHODS

The genes phzS, aprA, plcH, toxA, pilA and exoU were detected amongst 184 clinical strains, whose cytotoxicity and biofilm formation ability were evaluated as well. Phenotypic screening for drug susceptibility was conducted by standard antimicrobial susceptibility test and interpreted according to standards established by CLSI.

RESULTS

A total of 94 multidrug-sensitive and 90 multidrug-resistant isolates were included in this study. Statistically significant relationship was observed in the frequency of the toxA (p = 0.002) and plcH (p = 0.001) genes between multidrug-resistant and multidrug-sensitive strains. Moreover, thirteen genotypes were observed in multidrug-sensitive strains, and seven of them were included in multidrug-resistant groups. There was statistically significant correlation found between the presence of genotype IV (p = 0.001) and genotype VII (p = 0.001) in two subgroups. Additionally, It was found that genotype III isolates exhibited most obvious cytotoxicity, and multidrug-resistant isolates of genotype III showed the most significant cytotoxicity. Moreover, the strains of strong biofilm-formation accounted for a relatively high proportion in genotype III and VI groups.

CONCLUSION

These virulence genes could form abundant genotype varieties, whose overall number is greater in multi-sensitive strains. In addition, particular genotypes were characteristically distributed and exhibited different cytotoxicity and biofilm-formation abilities.

Risk Factors for Development and Mortality of Carbapenem-Resistant Pseudomonas aeruginosa Bloodstream Infection in a Chinese Teaching Hospital: A Seven-Year Retrospective Study

Objective

Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative opportunistic pathogen, which can cause acute and chronic infections, often resulting in high mortality. The aim of this study was to investigate the risk factors for the development and mortality of patients with carbapenem-resistant P. aeruginosa bloodstream infection (CRPA BSI).

Methods

A total of 112 patients with CRPA BSI and 112 patients with carbapenem-sensitive P. aeruginosa (CSPA) BSI were included from a Chinese teaching hospital from January 2017 to December 2023 in this retrospective cohort study. The detection rate, antimicrobial susceptibility of P. aeruginosa and clinical characteristics of these patients were investigated. Multivariable logistic regression analysis was used to identify risk factors for the development and outcomes of CRPA BSI.

Results

In the past 7 years, 7480 blood samples of P. aeruginosa were cultured in the hospital. The detection rates of CRPA, multidrug resistant P. aeruginosa (MDRPA), and difficult-to-treat resistant P. aeruginosa (DTRPA) BSI increased annually (26% to 47%, 10% to 36% and 5% to 15%, respectively). CRPA showed high resistance to conventional antibiotics. Chronic lung disease (OR 3.953, 95% CI 1.131-13.812), transplantation (OR 2.837, 95% CI 1.036-7.770), multi-organ failure (OR 4.815, 95% CI 1.949-11.894), pre-infection within CRPA (OR 9.239, 95% CI 3.441-24.803), and exposure to carbapenems within 90 days (OR 2.734, 95% CI 1.052 -7.106) were independent risk factors for the development of CRPA bacteremia. Sepsis or septic shock (OR 8.774, 95% CI 3.140-24.515, p = 0.001) were independent risk factors of mortality.

Conclusion

Chronic lung disease, transplantation, multi-organ failure, prior CRPA infection, and prior carbapenems exposure are independent risk factors for the development of CRPA bacteremia. Sepsis or septic shock increases 28-day mortality. To investigate the molecular mechanisms of carbapenem-resistance of P. aeruginosa, standardize antibiotic usage, and assess risk factors for the development and mortality of CRPA BSI are beneficial to control infection and reduce death.