Pathogen-host interactions in Pseudomonas aeruginosa pneumonia

Transcriptomics of Pseudomonas aeruginosa PA14 upon deletion of the sigma factor RpoS

We report RNA-seq data of Pseudomonas aeruginosa PA14 (UCBPP-PA14) and an isogenic rpoS-STOP mutant generated using CRISPR/Cas9 base editing. Transcriptomic profiling during exponential growth in rich medium highlights the regulatory influence of RpoS. These data enable exploration of RpoS-dependent responses in the virulent PA14 strain.

FleQ finetunes the expression of a subset of BrlR-activated genes to enable antibiotic tolerance by Pseudomonas aeruginosa biofilms

The transcriptional regulator FleQ contributes to Pseudomonas aeruginosa biofilm formation by activating the expression and biosynthesis of matrix exopolysaccharides in a manner dependent on c-di-GMP. However, little is known about the role of FleQ in the antibiotic tolerance phenotype of P. aeruginosa biofilms. Inactivation of fleQ impaired biofilm formation and rendered biofilms susceptible to tobramycin and norfloxacin. The phenotypes were similar to biofilms inactivated in sagS encoding the orphan sensor SagS that promotes the switch from planktonic to biofilm growth via BfiSR and antibiotic tolerance via BrlR. While FleQ was found to contribute to biofilm formation independently of SagS and BfiSR, FleQ instead converged with SagS-dependent regulation at the level of BrlR. This was supported by multicopy expression of sagS failing to restore biofilm antibiotic tolerance by ΔfleQ to wild-type levels (and vice versa) and by biofilms formed by the ΔfleQΔsagS double mutant being as susceptible as ΔfleQ and ΔsagS biofilms. Increased antibiotic susceptibility was independent of BrlR abundance or BrlR DNA binding but coincided with significantly reduced transcript abundance of the BrlR-activated mexCD-oprJ and PA1874-77, encoding an ABC transporter previously shown to contribute to the tolerance of biofilms to tobramycin and norfloxacin. FleQ- dependent regulation of gene expression was indirect. Co-immunoprecipitation and BACTH assays indicated FleQ to interact with SagS via its HisKA-Rec domain, likely suggesting FleQ and SagS to likely work in concert to enable biofilm antibiotic tolerance, by finetuning the expression of BrlR activated genes.IMPORTANCEIn P. aeruginosa, FleQ inversely regulates the expression of genes encoding flagella and biofilm matrix components, including exopolysaccharide (Pel, Psl) in a manner dependent on the levels of c-di-GMP. Our findings expand on the role of FleQ from regulating the transition to the biofilm mode of growth to FleQ contributing to the antimicrobial tolerance phenotype of biofilms, by FleQ affecting the expression of PA1874-77, a downstream target of the SagS-dependent transcriptional regulator BrlR. Importantly, our findings suggest FleQ works in concert with SagS, likely via FleQ-SagS protein-protein interactions, to enable the formation of inherently tolerant P. aeruginosa biofilms.

hmuSTUV operon positively regulates the alginate gene cluster to mediate the pathogenicity of Pseudomonas donghuensis HYS

Pseudomonas donghuensis HYS is highly virulent to Caenorhabditis elegans, but with mechanistic details that are not fully understood. The hmuSTUV operon was reported to participate in the synthesis of heme in Pseudomonas. However, the exact role of the hmuSTUV operon in Pseudomonas virulence has not been elucidated. In this study, we report for the first time that the hmuSTUV operon in P. donghuensis HYS causes host virulence, and that hmuS was a key gene for the toxicity of this operon. Furthermore, RNA-seq data showed that hmuS deletion inhibited alginate gene expression, thereby inhibiting biofilm formation. The hmuSTUV operon and alginate gene cluster are conserved in Pseudomonas. By constructing mutant strains carrying GFP, we found that the hmuS deletion reduced colonisation of HYS to the host gut. Moreover, the expression of the alginate gene cluster was controlled by the construction of a L-arabinose-inducible promoter. hmuS positively regulated alginate gene cluster expression, mediating bacterial virulence against C. elegans. In addition, HYS originating from the East Lake of Wuhan City was more pathogenic to zebrafish than any other pathogenic Pseudomonas, through impairment of zebrafish neurodevelopment and locomotor ability, by colonizing to the zebrafish brain. In conclusion, the hmuSTUV operon positively regulated the alg gene cluster, thereby disabling bacterial biofilm formation and colonisation to mediate bacterial pathogenicity to the host. These novel findings revealed the critical interaction between the hmuSTUV operon and the alg gene cluster in the bacterial virulence of Pseudomonas, providing new insights into Pseudomonas pathogenicity.

Type IV PilD mutant stimulates the formation of persister cells in Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa clinical isolates that lack motility do not express type IV pilin, yet the biological roles of this absence in the infection process remain poorly understood.

OBJECTIVES

We asked whether the absence of motility in these bacteria is associated with increased antibiotic persistence.

METHODS

In this study, we analysed type IV PilD protein sequences in the database and conducted antibiotic-tolerant persister cell assays.

RESULTS

We found that PilD variants were common in P. aeruginosa clinical isolates. Our results revealed that inactivation of PilD resulted in a significantly higher level of surviving persister cells following ciprofloxacin treatment. This PilD-mediated persistence did not involve previously described mechanisms, such as phenazine pyocyanin, biofilm or stringent response.

CONCLUSIONS

Our findings connect the non-motility of clinical P. aeruginosa isolates with the survival of persister cells, highlighting the clinical significance for the development of strategies to eradicate P. aeruginosa infections.

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.

Pseudomonas mendocina bacteremia: A case study from Indian subcontinent

Members of Pseudomonadaceae family are opportunistic pathogens that have been classified under various groups. Pseudomonas mendocina was first reported at Mendoza in 1970 with its first documented human infection in 1992. We present a case of bacteremia caused by Pseudomonas mendocina in 59-year-old immune-compromised patient from a tertiary-care teaching hospital. This is first reported case of bacteremia and the third case of infection caused by Pseudomonas mendocina from India. Although twenty-one cases of Pseudomonas mendocina infection have already been published from different countries.

Phage-Encoded Antimicrobial Peptide gp28 Demonstrates LL-37-Like Antimicrobial Activity Against Multidrug-Resistant Pseudomonas aeruginosa

Background

Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative bacterial pathogen commonly associated with nosocomial infections. Treatment of P. aeruginosa infections is notoriously difficult due to biofilm formation and antibiotic resistance. Antimicrobial peptides (AMPs) are thought to be promising new antimicrobials. Gp28, a phage-derived AMP, is a novel class of characterized phage AMPs with activity against Escherichia coli in a manner similar to the human peptide LL-37. LL-37 exhibits strong antimicrobial activity against P. aeruginosa as well as biofilm disruption and synergy with certain antibiotics posing the question whether gp28 could act similarly.

Methods

Antibacterial activity of gp28 against P. aeruginosa was established using growth inhibition assays, with minimum inhibitory concentration calculated. Biofilm disruption was assessed using crystal violet staining and scanning electron microscopy. Combined treatment of gp28 with tobramycin against P. aeruginosa was measured using a modified time-kill assay at sublethal concentrations.

Results

Gp28 inhibits P. aeruginosa planktonic growth, with a minimum inhibitory concentration of 109 μg mL-1 and disrupts established biofilms. We demonstrate that gp28 increases the susceptibility of P. aeruginosa to tobramycin.

Conclusions

Gp28 demonstrates potential for development as a putative therapeutic agent against a clinically resistant P. aeruginosa strain either alone or in combination with the frontline antibiotic tobramycin.

Dual-function regulator MexL as a target to control phenazines production and pathogenesis of Pseudomonas aeruginosa

Antibiotic resistance or tolerance of pathogens has become one of the global public crises. Finding new drug targets may open up a way of infection control. Phenazine pyocyanin (PYO) is an important virulence factor produced by the pathogen Pseudomonas aeruginosa. Here we show that a multidrug efflux pump repressor, MexL, acts as a transcriptional activator to enhance phenazines production via binding with a conserved DNA motif within the promoters of phenazines biosynthesis genes. Moreover, PYO functions as a self-regulating ligand of MexL for restricting its own production and the mexL knockout attenuates the virulence and antibiotics tolerance of P. aeruginosa. Based on the structure of MexL we resolve, we find two antimicrobials that can interact with MexL to reduce the PYO production and virulence of P. aeruginosa. Our in vivo studies suggest that the antimicrobials combination by using MexL-antagonists to reduce bacterial virulence and enhance the efficacy of common antibiotics can be an effective way to combat P. aeruginosa infection.

Chlorogenic acid inhibits Pseudomonas toxin pyocyanin and activates mitochondrial UPR to protect host against pathogen infection

Mitochondria are required for protecting host against pathogenic bacteria by activating mitochondrial unfolded protein response (UPRmt). Chlorogenic acid (CGA), a phenolic acid compound of green coffee extracts and tea has been shown to exhibit activities such as antioxidant, antibacterial, hepatoprotective, cardioprotective, anti-inflammatory, neuroprotective, anti-obesity. However, whether CGA regulates innate immunity and the underlying molecular mechanisms remain unknown. In this study, we found that CGA increased resistance to Gram-negative pathogen Pseudomonas aeruginosa PA14 in dose dependent manner. Meanwhile, CGA enhanced innate immunity in Caenorhabditis elegans by reducing intestinal bacterial burden. CGA also inhibited the proliferation of pathogenic bacteria. Importantly, CGA inhibited the production of Pseudomonas toxin pyocyanin (PYO) to protect C. elegans from P. aeruginosa PA14 infection. Furthermore, CGA activated the UPRmt and expression of antibacterial peptide genes to promote innate immunity in C. elegans via transcription factor ATFS-1(activating transcription factor associated with stress-1). Unexpectedly, CGA enhanced innate immunity independently of other known innate immune pathways. Intriguingly, CGA also protected mice from P. aeruginosa PA14 infection and activated UPRmt. Our work revealed a conserved mechanism by which CGA promoted innate immunity and boosted its therapeutic application in the treatment of pathogen infection.

Genotypic and phenotypic analyses of two distinct sets of Pseudomonas aeruginosa urinary tract isolates

Introduction. Urinary tract infections (UTIs) are associated with a high burden of morbidity, mortality and cost. Pseudomonas aeruginosa employs a myriad of virulence factors, including biofilm formation and motility mechanisms, to cause infections including persistent UTIs. P. aeruginosa is highly resistant to antibiotics, and the World Health Organization has identified it as a pathogen for which novel antimicrobials are urgently required.Gap statement. Genotypic and phenotypic characterization of P. aeruginosa from UTIs is underreported. In addition, the rise of antimicrobial resistance (AMR) is a cause for concern, particularly in many countries where surveillance is severely lacking.Aim. To identify genotypic and phenotypic characteristics of P. aeruginosa UTI isolates sourced from the UK and the state of Kuwait, with an emphasis on genotypic diversity and AMR.Methods. Twenty-three P. aeruginosa UTI isolates were sourced from the UK and Kuwait. To establish the phenotypes of UK isolates, growth analysis, biofilm formation assays, motility assays and antibiotic disc diffusion assays were performed. Whole-genome sequencing, antimicrobial susceptibility assays and in silico detection of AMR-associated genes were conducted on both sets of isolates.Results. In terms of their phenotypic characteristics and genomic composition, the UTI isolates varied. Multiple resistance genes are associated with resistance to various classes of antibiotics, such as aminoglycosides, fluoroquinolones and β-lactams, particularly in isolates from Kuwait. Extreme antibiotic resistance was detected in the isolates obtained from Kuwait, indicating that the country may be an antibiotic resistance hotspot.Conclusion. This study highlights that isolates from UTIs are diverse and can display extremely high resistance. Surveillance in countries such as Kuwait is currently limited, and this study suggests the need for greater surveillance.

Etiology of Hospital-Acquired Pneumonia (HAP) and Ventilator-Associated Pneumonia (VAP) in Tertiary-Care Hospitals in Thailand: A Multicenter, Retrospective Cohort Study

Purpose

To describe the top three causative organisms of hospital acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) in Thailand.

Patients and Methods

This multi-center retrospective cohort study included HAP/VAP patients hospitalized in 2019 in three university-affiliated hospitals and a private hospital in Bangkok, Thailand. Medical records of patients with a documented diagnosis of nosocomial pneumonia (NP) were systematically reviewed to collect data on demographic, clinical, microbiological, and 30-day readmission due to NP.

Results

A total of 240 patients were included in the study, comprises patients with VAP (62.9%), HAP (36.7%), and ventilated HAP (vHAP) (0.4%). All of the patients had late-onset NP, occurring after five days of hospitalization with median time to NP of 13 days (interquartile range [IQR] 6-25 days) from admission. The top three causative pathogens of NP were Acinetobacter baumannii (44.2%), Pseudomonas aeruginosa (34.6%), and Klebsiella pneumoniae (28.3%). A high rate of carbapenem resistance (CR) in A. baumannii (92.5%) was observed. Lower rates of CR were observed in K. pneumoniae (20.6%) and P. aeruginosa isolates (16.9%). Readmission rate due to NP within 30 days after discharge was less than 2% with median time of 4 days (IQR 3-20 days) after discharge. After diagnosis of NP, 19 patients were transferred to intensive care units with median length of stays of 11 days (IQR 3-24 days). Fifty-one percent of HAP patients received mechanical ventilation support after the diagnosis of NP with median length of mechanical ventilation use of 12 days (IQR 6-22 days).

Conclusion

A. baumannii, with its significant carbapenem resistance, presents a major HAP/VAP pathogens and imposes a substantial burden on healthcare resources in this study. Implementation of regular surveillance for causative organisms of NP and their susceptibility profiles are critical for the success of HAP/VAP management, and reducing the related burden of healthcare resources.

Comparative antibacterial activity of clove extract against Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen belonging to the γ-proteobacteria family, known to cause pneumonia linked with ventilator use and nosocomial infections. With the increasing prevalence of antibiotic-resistant bacteria, there is a pressing need to identify alternatives to conventional antibiotics. Plant-derived substances (PDSs) offer potential not only as antibacterial agents but also as modulators of antibiotic resistance. In this study, diffusion assay using disc agar, and the minimum inhibitory concentration (MIC) assay of each imipenem, amoxicillin-clavulanic acid, and clove extract was determined. The clove extract was analyzed via the UHPLC/MS, and the checkerboard assay was employed to evaluate the potential synergistic effects of combining clove extract with both antibiotics. The combination of clove extract to each antibiotic led to a significant reduction in their respective MICs. Moreover, each antibiotic exhibited synergistic effects on the fractional inhibitory concentration value (FIC) of clove extract. The analysis identified seventeen components in the clove extract, predominantly flavonoids and phenolic compounds. The antibacterial efficacy of the Syzygium aromaticum Myrtaceae extract against P. aeruginosa indicated its potential as a promising antibacterial agent capable of enhancing the effectiveness of existing medications.

Fatty Acids Derived from Royal Jelly Exert Anti-Inflammatory and Antibacterial Activities in the Treatment of Pseudomonas aeruginosa-Induced Acute Pneumonia

Pseudomonas aeruginosa, an opportunistic pathogen, commonly causes hospital-acquired pneumonia. Royal jelly fatty acids (RJFAs), a mixture of various fatty acids extracted from royal jelly, exhibit antibacterial and anti-inflammatory properties in treating many infectious diseases. Nevertheless, the therapeutic mechanisms of RJFAs in treatment of acute P. aeruginosa pulmonary infection are still unclear. Herein, we initially extracted the fatty acids from royal jelly and characterized their chemical constituents using headspace gas chromatography-mass spectrometry. Furthermore, we examined the antibacterial effect of RJFAs in vitro and explored its therapeutic effect and molecular mechanisms in treating acute P. aeruginosa pulmonary infection in vivo. The in vitro antibacterial studies revealed that RJFAs significantly inhibited P. aeruginosa growth. Moreover, the in vivo studies showed that the RJFAs effectively mitigated the lung damage and inflammation induced by P. aeruginosa through impairing neutrophil infiltration, reducing the bacterial load in lung and diminishing the production of proinflammatory cytokines, including tumor necrosis factor (TNF-α), interleukin (IL-1β), IL-6, and macrophage inflammatory protein-2 (MIP-2). In addition, the mice treated with RJFAs exhibited reduced phosphorylation of extracellular signal-regulated kinase (ERK), p38, c-Jun N-terminal kinase (JNK), c-Jun, and nuclear factor-kappa B (NF-κB) p65 in the lung tissues in comparison with that of the mice without drug treatment. These findings demonstrated that RJFAs exhibited significant antibacterial and anti-inflammatory effects in treating the P. aeruginosa-induced acute pneumonia, and the anti-inflammatory effects were exerted through suppressing the mitogen-activated protein kinase/activator protein-1 (MAPK/AP-1) pathway and NF-κB activation, suggesting a promising therapeutic potential of RJFAs against acute bacterial pneumonia.

Choline metabolism modulates cyclic-di-GMP signaling and virulence of Pseudomonas aeruginosa in a macrophage infection model

BACKGROUND

Bacterial pathogens frequently encounter host-derived metabolites during their colonization and invasion processes, which can serve as nutrients, antimicrobial agents, or signaling molecules for the pathogens. The essential nutrient choline (Cho) is widely known to be utilized by a diverse range of bacteria and may undergo conversion into the disease-associated metabolite trimethylamine (TMA). However, the impact of choline metabolism on bacterial physiology and virulence remains largely unexplored.

METHODS

Here, we employed an in vitro infection model to investigate the role of Cho in intracellular survival and virulence of Pseudomonas aeruginosa (P. aeruginosa). Additionally, a comprehensive RNA-seq based transcriptomic analysis and various phenotypic assays were performed to elucidate the impacts of Cho on P. aeruginosa.

RESULTS

We observed that the Cho metabolite glycine betaine (GB) effectively reduced intracellular levels of cyclic-di-GMP (c-di-GMP). Supplementation of Cho or GB in P. aeruginosa had thus affected c-di-GMP regulated phenotypes, such as pyoverdine production, biofilm formation, and mobility. Depletion of Cho metabolism through knockout of the betAB operon resulted in compromised intracellular survival of P. aeruginosa. Notably, the P. aeruginosa betAB mutant elicited a more robust protective inflammatory response compared to the wild-type strain.

CONCLUSION

Our study showed that P. aeruginosa Cho metabolism not only interferes host nutritional immunity, but also directly affect multiple virulence phenotypes through modulation of c-di-GMP signaling.

Elucidating molecular mechanism and chemical space of chalcones through biological networks and machine learning approaches

We developed a bio-cheminformatics method, exploring disease inhibition mechanisms using machine learning-enhanced quantitative structure-activity relationship (ML-QSAR) models and knowledge-driven neural networks. ML-QSAR models were developed using molecular fingerprint descriptors and the Random Forest algorithm to explore the chemical spaces of Chalcones inhibitors against diverse disease properties, including antifungal, anti-inflammatory, anticancer, antimicrobial, and antiviral effects. We generated and validated robust machine learning-based bioactivity prediction models (https://github.com/RatulChemoinformatics/QSAR) for the top genes. These models underwent ROC and applicability domain analysis, followed by molecular docking studies to elucidate the molecular mechanisms of the molecules. Through comprehensive neural network analysis, crucial genes such as AKT1, HSP90AA1, SRC, and STAT3 were identified. The PubChem fingerprint-based model revealed key descriptors: PubchemFP521 for AKT1, PubchemFP180 for SRC, PubchemFP633 for HSP90AA1, and PubchemFP145 and PubchemFP338 for STAT3, consistently contributing to bioactivity across targets. Notably, chalcone derivatives demonstrated significant bioactivity against target genes, with compound RA1 displaying a predictive pIC50 value of 5.76 against HSP90AA1 and strong binding affinities across other targets. Compounds RA5 to RA7 also exhibited high binding affinity scores comparable to or exceeding existing drugs. These findings emphasize the importance of knowledge-based neural network-based research for developing effective drugs against diverse disease properties. These interactions warrant further in vitro and in vivo investigations to elucidate their potential in rational drug design. The presented models provide valuable insights for inhibitor design and hold promise for drug development. Future research will prioritize investigating these molecules for mycobacterium tuberculosis, enhancing the comprehension of effectiveness in addressing infectious diseases.

Single cell autofluorescence imaging reveals immediate metabolic shifts of neutrophils with activation across biological systems

Neutrophils, the most abundant leukocytes in human peripheral circulation, are crucial for the innate immune response. They are typically quiescent but rapidly activate in response to infection and inflammation, performing diverse functions such as oxidative burst, phagocytosis, and NETosis, which require significant metabolic adaptation. Deeper insights into such metabolic changes will help identify regulation of neutrophil functions in health and diseases. Due to their short lifespan and associated technical challenges, the metabolic processes of neutrophils are not completely understood. This study uses optical metabolic imaging (OMI), which entails optical redox ratio and fluorescence lifetime imaging microscopy of intrinsic metabolic coenzymes NAD(P)H and FAD to assess the metabolic state of single neutrophils. Primary human neutrophils were imaged in vitro under a variety of activation conditions and metabolic pathway inhibitors, while metabolic and functional changes were confirmed with mass spectrometry, oxidative burst, and NETosis measurements. Our findings show that neutrophils undergo rapid metabolic remodeling to a reduced redox state indicated by changes in NAD(P)H lifetime and optical redox ratio, with a shift to an oxidized redox state during activation. Additionally, single cell OMI analysis reveals a heterogeneous metabolic response across neutrophils and human donors to live pathogen infection ( Pseudomonas aeruginosa and Toxoplasma gondii ). Finally, consistent OMI changes with activation were confirmed between in vitro human and in vivo zebrafish larvae neutrophils. This study demonstrates the potential of OMI as a versatile tool for studying neutrophil metabolism and underscores its use across different biological systems, offering insights into neutrophil metabolic activity and function at a single cell level.

N-Alkane Assimilation by Pseudomonas aeruginosa and Its Interactions with Virulence and Antibiotic Resistance

Pseudomonas aeruginosa strains with potential for degrading n-alkanes are frequently cultured from hydrocarbon-contaminated sites. The initial hydroxylation step of long-chain n-alkanes is mediated by the chromosomally encoded AlkB1 and AlkB2 alkane hydroxylases. The acquisition of an additional P. putida GPo1-like alkane hydroxylase gene cluster can extend the substrate range assimilated by P. aeruginosa to Collapse

Key Words

• AlkB
• MexAB-OprM
• P. aeruginosa
• alkane hydroxylase
• antibiotic resistance
• hydrocarbon pollution
• solvent tolerance

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MESH Headings Collapse

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Affiliation(s)

Balázs Libisch Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, H-2100 Gödöllő, Hungary

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16S rDNA-Based Amplicon Analysis Unveiled a Correlation Between the Bacterial Diversity and Antibiotic Resistance Genes of Bacteriome of Commercial Smokeless Tobacco Products

The distribution of bacterial-derived antibiotic resistance genes (ARGs) in smokeless tobacco products is less explored and encourages understanding of the ARG profile of Indian smokeless tobacco products. Therefore, in the present investigation, ten commercial smokeless tobacco products were assessed for their bacterial diversity to understand the correlation between the inhabitant bacteria and predicted ARGs using a 16S rDNA-based metagenome analysis. Overall analysis showed the dominance of two phyla, i.e., Firmicutes (43.07%) and Proteobacteria (8.13%) among the samples, where Bacillus (9.76%), Terribacillus (8.06%), Lysinibacillus (5.8%), Alkalibacterium (5.6%), Oceanobacillus (3.52%), and Dickeya (3.1%) like genera were prevalent among these phyla. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt)-based analysis revealed 217 ARGs which were categorized into nine groups. Cationic antimicrobial polypeptides (CAMP, 33.8%), vancomycin (23.4%), penicillin-binding protein (13.8%), multidrug resistance MDR (10%), and β-lactam (9.3%) were among the top five contributors to ARGs. Staphylococcus, Dickeya, Bacillus, Aerococcus, and Alkalibacterium showed their strong and significant correlation (p value < 0.05) with various antibiotic resistance mechanisms. ARGs of different classes (blaTEM, blaSHV, blaCTX, tetX, vanA, aac3-II, mcr-1, intI-1, and intI2) were also successfully amplified in the metagenomes of SMT samples using their specific primers. The prevalence of ARGs in inhabitant bacteria of smokeless tobacco products suggests making steady policies to regulate the hygiene of commercial smokeless tobacco products.

A multiantigenic antibacterial nanovaccine utilizing hybrid membrane vesicles for combating Pseudomonas aeruginosa infections

Bacterial infections, especially those caused by multidrug-resistant pathogens, pose a significant threat to public health. Vaccines are a crucial tool in fighting these infections; however, no clinically available vaccine exists for the most common bacterial infections, such as those caused by Pseudomonas aeruginosa. Herein, a multiantigenic antibacterial nanovaccine (AuNP@HMV@SPs) is reported to combat P. aeruginosa infections. This nanovaccine utilizes the hybrid membrane vesicles (HMVs) created by fusing macrophage membrane vesicles (MMVs) with bacterial outer membrane vesicles (OMVs). The HMVs mitigate the toxic effects of both OMVs and bacterial secreted toxins (SP) adsorbed on the surface of MMVs, while preserving their stimulating properties. Gold nanoparticles (AuNPs) are utilized as adjuvant to enhance immune response without comprising safety. The nanovaccine AuNP@HMV@SPs induces robust humoral and cellular immune responses, leading to destruction of bacterial cells and neutralization of their secreted toxins. In murine models of septicemia and pneumonia caused by P. aeruginosa, AuNP@HMV@SPs exhibits superior prophylactic efficacy compared to control groups including OMVs, or MMVs@SPs and HMV@SPs, achieving 100% survival in septicemia and > 99.9% reduction in lung bacterial load in pneumonia. This study highlights AuNP@HMV@SPs as a safe and effective antibacterial nanovaccine, targeting both bacteria and their secreted toxins, and offers a promising platform for developing multiantigenic antibacterial vaccines against multidrug-resistant pathogens.

An innovative approach to decoding genetic variability in Pseudomonas aeruginosa via amino acid repeats and gene structure profiles

Pseudomonas aeruginosa, a common pathogen in nosocomial infections, presents significant global health challenges due to its high prevalence and mortality rates. However, the origins and distribution of this bacterium remain unclear, partly due to the lack of effective gene typing methods. This situation necessitates the establishment of trustworthy and high-resolution protocol for differentiating closely related P. aeruginosa strains. In this context, the present study attempted to undertake a comparative genomic analysis of multiple P. aeruginosa strains available in the public database NCBI, with the goal of identifying potential genetic markers for measuring the genetic diversity. The preliminary comparative analysis of 816 P. aeruginosa strains revealed notable variations in two genes-specifically, the CDF family iron/cobalt efflux transporter AitP and the protease modulator HflC-across 44 strains. These variations were associated with single amino acid repeats (SHRs) that responsible for encoding histidine residue. Additionally, comparative gene map analysis revealed differential clustering patterns in the Rsx and TAXI genes among 16 strains. Interestingly, the gene structure pattern observed in TAXI groups displayed a strong correlation with the SHRs pattern in the CDF and HflC groups. In addition, the SHRs pattern of CDF and HflC were strongly correlated with MLST sequence type number. Overall, the study present a novel genetic markers based on SHRs and gene cluster patterns, offering a reliable method for genotyping of P. aeruginosa.

The RNA from Pseudomonas aeruginosa Reduces Neutrophil Responses Favoring Bacterial Survival

INTRODUCTION

Epithelial and endothelial cells modulate innate immune responses in the lung, including the arrival of neutrophils (PMN), which are crucial cells for the antibacterial host defense. Cells are exposed to prokaryotic RNA (pRNA) during bacterial infections and different pRNA may promote or attenuate the inflammatory response on different immune cells. Pseudomonas aeruginosa (PAE) can cause severe pneumonia and has several immune-evading mechanisms. The aim of this study was to determine the effects of the RNA from PAE (RNAPAE) on lung epithelial, endothelial cells, and PMN, and its impact on bacterial elimination.

METHODS

Purified total RNAPAE was used as a stimulus on a human lung epithelial cell line (Calu-6), human microvascular endothelial cell line HMEC-1 and isolated healthy human PMN. Activation and cytokine secretion were evaluated. In addition, PMN elimination of live ECO or PAE was determined in the presence of RNAPAE.

RESULTS

We found that RNAPAE either induced a pro-inflammatory response on Calu-6 and HMEC-1 or PMN. Pre-stimulation of PMN with RNAPAE diminished activation and chemotaxis induced by live bacteria. Moreover, we found that RNAPAE reduced phagocytosis of live ECO. Finally, we also found that non-degraded fragments of small RNA (<200 bp) were responsible for the PMN microbicidal attenuation during PAE elimination.

CONCLUSION

Our results indicated that short fragments of RNAPAE diminished the immune response of PMN favoring bacterial survival.

Multiple antimicrobial and immune-modulating activities of cysteamine in infectious diseases

Infectious diseases are a major threat to global health and cause millions of deaths every year, particularly in developing countries. The emergence of multidrug resistance challenges current antimicrobial treatments, inducing uncertainty in therapeutic protocols. New compounds are therefore necessary. A drug repurposing approach could play a critical role in developing new treatments used either alone or in combination with standard therapy regimens. Herein, we focused on cysteamine, an aminothiol endogenously synthesized by human cells during the degradation of coenzyme-A, which is a drug approved for the treatment of nephropathic cystinosis. Cysteamine influences many biological processes due to the presence of the highly reactive thiol group. This review provides an overview of cysteamine-mediated effects on different viruses, bacteria and parasites, with a particular focus on infections caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Mycobacterium tuberculosis, non-tuberculous mycobacteria (NTM), and Pseudomonas aeruginosa. Evidences for a potential use of cysteamine as a direct antimicrobial agent and/or a host-directed therapy, either alone or in combination with other antimicrobial drugs, are described.

Cilostazol is a promising anti-pseudomonal virulence drug by disruption of quorum sensing

Resistance to antibiotics is a critical growing public health problem that desires urgent action to combat. To avoid the stress on bacterial growth that evokes the resistance development, anti-virulence agents can be an attractive strategy as they do not target bacterial growth. Quorum sensing (QS) systems play main roles in controlling the production of diverse virulence factors and biofilm formation in bacteria. Thus, interfering with QS systems could result in mitigation of the bacterial virulence. Cilostazol is an antiplatelet and a vasodilator FDA approved drug. This study aimed to evaluate the anti-virulence activities of cilostazol in the light of its possible interference with QS systems in Pseudomonas aeruginosa. Additionally, the study examines cilostazol's impact on the bacterium's ability to induce infection in vivo, using sub-inhibitory concentrations to minimize the risk of resistance development. In this context, the biofilm formation, the production of virulence factors and influence on the in vivo ability to induce infection were assessed in the presence of cilostazol at sub-inhibitory concentration. Furthermore, the outcome of combination with antibiotics was evaluated. Cilostazol interfered with biofilm formation in P. aeruginosa. Moreover, swarming motility, biofilm formation and production of virulence factors were significantly diminished. Histopathological investigation revealed that liver, spleen and kidney tissues damage was abolished in mice injected with cilostazol-treated bacteria. Cilostazol exhibited a synergistic outcome when used in combination with antibiotics. At the molecular level, cilostazol downregulated the QS genes and showed considerable affinity to QS receptors. In conclusion, Cilostazol could be used as adjunct therapy with antibiotics for treating Pseudomonal infections. This research highlights cilostazol's potential to combat bacterial infections by targeting virulence mechanisms, reducing the risk of antibiotic resistance, and enhancing treatment efficacy against P. aeruginosa. These findings open avenues for repurposing existing drugs, offering new, safer, and more effective infection control strategies.

AAV-vectored expression of monospecific or bispecific monoclonal antibodies protects mice from lethal Pseudomonas aeruginosa pneumonia

Pseudomonas aeruginosa poses a significant threat to immunocompromised individuals and those with cystic fibrosis. Treatment relies on antibiotics, but persistent infections occur due to intrinsic and acquired resistance of P. aeruginosa towards multiple classes of antibiotics. To date, there are no licensed vaccines for this pathogen, prompting the urgent need for novel treatment approaches to combat P. aeruginosa infection and persistence. Here we validated AAV vectored immunoprophylaxis as a strategy to generate long-term plasma and mucosal expression of highly protective monoclonal antibodies (mAbs) targeting the exopolysaccharide Psl (Cam-003) and the PcrV (V2L2MD) component of the type-III secretion system injectosome either as single mAbs or together as a bispecific mAb (MEDI3902) in a mouse model. When administered intramuscularly, AAV-αPcrV, AAV-αPsl, and AAV-MEDI3902 significantly protected mice challenged intranasally with a lethal dose of P. aeruginosa strains PAO1 and PA14 and reduced bacterial burden and dissemination to other organs. While all AAV-mAbs provided protection, AAV-αPcrV and AAV-MEDI3902 provided 100% and 87.5% protection from a lethal challenge with 4.47 × 107 CFU PAO1 and 87.5% and 75% protection from a lethal challenge with 3 × 107 CFU PA14, respectively. Serum concentrations of MEDI3902 were ~10× lower than that of αPcrV, but mice treated with this vector showed a greater reduction in bacterial dissemination to the liver, lung, spleen, and blood compared to other AAV-mAbs. These results support further investigation into the use of AAV vectored immunoprophylaxis to prevent and treat P. aeruginosa infections and other bacterial pathogens of public health concern for which current treatment strategies are limited.

Phylogenetic Tracing of Evolutionarily Conserved Zonula Occludens Toxin Reveals a "High Value" Vaccine Candidate Specific for Treating Multi-Strain Pseudomonas aeruginosa Infections

Extensively drug-resistant Pseudomonas aeruginosa infections are emerging as a significant threat associated with adverse patient outcomes. Due to this organism's inherent properties of developing antibiotic resistance, we sought to investigate alternative strategies such as identifying "high value" antigens for immunotherapy-based purposes. Through extensive database mining, we discovered that numerous Gram-negative bacterial (GNB) genomes, many of which are known multidrug-resistant (MDR) pathogens, including P. aeruginosa, horizontally acquired the evolutionarily conserved gene encoding Zonula occludens toxin (Zot) with a substantial degree of homology. The toxin's genomic footprint among so many different GNB stresses its evolutionary importance. By employing in silico techniques such as proteomic-based phylogenetic tracing, in conjunction with comparative structural modeling, we discovered a highly conserved intermembrane associated stretch of 70 amino acids shared among all the GNB strains analyzed. The characterization of our newly identified antigen reveals it to be a "high value" vaccine candidate specific for P. aeruginosa. This newly identified antigen harbors multiple non-overlapping B- and T-cell epitopes exhibiting very high binding affinities and can adopt identical tertiary structures among the least genetically homologous P. aeruginosa strains. Taken together, using proteomic-driven reverse vaccinology techniques, we identified multiple "high value" vaccine candidates capable of eliciting a polarized immune response against all the P. aeruginosa genetic variants tested.

In vitro activity of cefiderocol in Pseudomonas aeruginosa isolates from people with cystic fibrosis recovered during three multicentre studies in Spain

OBJECTIVES

Despite the introduction of cystic fibrosis transmembrane conductance regulator (CFTR) modulators, Pseudomonas aeruginosa is still a major pathogen in people with cystic fibrosis (pwCF). We determine the activity of cefiderocol and comparators in a collection of 154 P. aeruginosa isolates recovered from pwCF during three multicentre studies performed in 17 Spanish hospitals in 2013, 2017 and 2021.

METHODS

ISO broth microdilution was performed and MICs were interpreted with CLSI and EUCAST criteria. Mutation frequency and WGS were also performed.

RESULTS

Overall, 21.4% were MDR, 20.8% XDR and 1.3% pandrug-resistant (PDR). Up to 17% of the isolates showed a hypermutator phenotype. Cefiderocol demonstrated excellent activity; only 13 isolates (8.4%) were cefiderocol resistant by EUCAST (none using CLSI). A high proportion of the isolates resistant to ceftolozane/tazobactam (71.4%), meropenem/vaborbactam (70.0%), imipenem/relebactam (68.0%) and ceftazidime/avibactam (55.6%) were susceptible to cefiderocol. Nine out of 13 cefiderocol-resistant isolates were hypermutators (P < 0.001). Eighty-three STs were detected, with ST98 being the most frequent. Only one isolate belonging to the ST175 high-risk clone carried blaVIM-2. Exclusive mutations affecting genes involved in membrane permeability, AmpC overexpression (L320P-AmpC) and efflux pump up-regulation were found in cefiderocol-resistant isolates (MIC = 4-8 mg/L). Cefiderocol resistance could also be associated with mutations in genes related to iron uptake (tonB-dependent receptors and pyochelin/pyoverdine biosynthesis).

CONCLUSIONS

Our results position cefiderocol as a therapeutic option in pwCF infected with P. aeruginosa resistant to most recent β-lactam/β-lactamase inhibitor combinations.

Biofilm generation and antibiotic resistant profile of extensive and multidrug resistant Pseudomonas aeruginosa from burn patients in Ahvaz: A cross-sectional study

Background and Aims

Multidrug and extensive drug-resistant Pseudomonas aeruginosa was extracted from burn patients referring to burn centers in southwest Iran so that biofilm generation and antibiotic resistance could be investigated.

Methods

A specific primer was used to confirm all our considered 110 P. aeruginosa culture-positive reports on 345 burn patients. The resistance of P. aeruginosa to seven antibiotics and Colistin with minimum inhibitory concentration (MIC) was assessed. Biofilm formation was assessed by the phenotypic study of specimens under Congo red agar and microtiter plate assays.

Results

One hundred and 10 clinical P. aeruginosa isolates taken from burn wound infections were validated. Among P. aeruginosa isolates, Piperacillin, Ceftazidime, Maeropenem, Gentamycin, and Gatifloacin had the highest resistance to antibiotics, while Ticarcillin-Clavulanic acid and Ceftolozane-Tazobactam showed the least resistance. MICs were then evaluated via the E test. Seven isolates were resistant to colistin. Colistin reference MICs for multidrug-resistant P. aeruginosa prevalence was 38%, while it was 22% for extensively drug-resistant (XDR) P. aeruginosa. One P. aeruginosa was pandrug-resistant (PDR). Under Congo red agar test, 66 isolates (67%) formed biofilms and black colonies, whereas 44 isolates (50%) had red colonies. In MTP, 76% formed biofilm. 40%, 32%, 21% of the isolates were strong, moderate, and weak biofilm formers, respectively, while 43% did not form biofilms.

Conclusion

The P. aeruginosa resistance to antimicrobial agents has largely challenged the control of the infection. Accordingly, a higher resistance occurred when the isolates were transferred to the patients. Less than 50% P. aeruginosa samples generated strong biofilms. Consequently, hygienic measurements are essential to inhibit P. aeruginosa transmission to hospitalized patients.

Dual action of benzaldehydes: Inhibiting quorum sensing and enhancing antibiotic efficacy for controlling Pseudomonas aeruginosa biofilms

Quorum sensing (QS) has a central role in biofilm lifestyle and antimicrobial resistance, and disrupting these signaling pathways is a promising strategy to control bacterial pathogenicity and virulence. In this study, the efficacy of three structurally related benzaldehydes (4-hydroxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde (vanillin) and 4-hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde)) in disrupting the las and pqs systems of Pseudomonas aeruginosa was investigated using bioreporter strains and computational simulations. Additionally, these benzaldehydes were combined with tobramycin and ciprofloxacin antibiotics to evaluate their ability to increase antibiotic efficacy in preventing and eradicating P. aeruginosa biofilms. To this end, the total biomass, metabolic activity and culturability of the biofilm cells were determined. In vitro assays results indicated that the aromatic aldehydes have potential to inhibit the las and pqs systems by > 80 %. Molecular docking studies supported these findings, revealing the aldehydes binding in the same pocket as the natural ligands or receptor proteins (LasR, PQSA, PQSE, PQSR). Benzaldehydes were shown to act as virulence factor attenuators, with vanillin achieving a 48 % reduction in pyocyanin production. The benzaldehyde-tobramycin combination led not only to a 60 % reduction in biomass production but also to a 90 % reduction in the metabolic activity of established biofilms. A similar result was observed when benzaldehydes were combined with ciprofloxacin. 4-Hydroxybenzaldehyde demonstrated relevant action in increasing biofilm susceptibility to ciprofloxacin, resulting in a 65 % reduction in biomass. This study discloses, for the first time, that the benzaldehydes studied are potent QS inhibitors and also enhancers of antibiotics antibiofilm activity against P. aeruginosa.

Investigating Sulforaphane's anti-virulence and anti-quorum sensing properties against Pseudomonas aeruginosa

Background

P. aeruginosa, a significant bacterium, can cause severe illness and resistance to antibiotics. Quorum sensing (QS) systems regulate virulence factors production. Targeting QS could reduce bacteria pathogenicity and prevent antibiotic resistance. Cruciferous vegetables contain sulforaphane, known for its anti-inflammatory, antioxidant, anticancer, and antimicrobial properties.

Aim

We aimed to examine the inhibitory influences of sulforaphane, at a sub-inhibitory concentration (¼ minimum inhibitory concentration, MIC), on virulence and QS in P. aeruginosa.

Materials and methods

The sulforaphane's anti-virulence actions at sub-inhibitory concentrations were explored in vitro and in vivo. A sub-MIC concentration of sulforaphane was combined with anti-pseudomonal drugs, and the results of this combination were assessed. The virtual affinity of sulforaphane for the receptors of QS was studied, and its effect on the expression of QS genes was quantified.

Results

Sulforaphane significantly decreased the biofilm formation, motility, ability to withstand oxidative stress, and the synthesis of virulence extracellular enzymes such as proteases, hemolysins, and elastase, as well as other virulence factors like pyocyanin. In addition, sulforaphane lessened the severity of P. aeruginosa infection in mice. Sulforaphane reduced the antipseudomonal antibiotics' MICs when used together, resulting in synergistic effects. The observed anti-virulence impacts were attributed to the ability of sulforaphane to inhibit QS via suppressing the QS genes' expression.

Conclusion

Sulforaphane shows promise as a potent anti-virulence and anti-QS agent that can be used alongside conventional antimicrobials to manage severe infections effectively. Furthermore, this study paves the way for further investigation of sulforaphane and similar structures as pharmacophores for anti-QS candidates.

Can environmental nebulization of lavender essential oil (L. angustifolia) improve welfare and modulate nasal microbiota of growing pigs?

The use of phytoextracts has been proposed as a method to improve animal welfare, also in pigs, by reducing stress and anxiety and improving performances. Lavandula angustifolia (Miller) essential oil (LaEO) is an interesting calming phytoextract that could be administered by inhalation for prolonged periods of time to help pigs coping with on-farm conditions. The aim of this study was to assess the effects of daily inhalation of vaporized LaEO on pigs' welfare and health indicators, and nasal microbiota, trying to understand whether this phytoextract represents a feasible tool to improve animal welfare under intensive farming conditions. Eighty-four crossbred barrows were randomly divided into 3 experimental groups: control (C); lavender (L): 3 vaporization sessions of 10 min each of a custom made 1% solution of LaEO; sham (S): same vaporization sessions of L group but only using the solution vehicle. Experimental readouts included growth parameters, behavioural traits, tail and skin lesions, hair steroids and nasal microbiota. L group animals did not show altered growth performance and seemed calmer (increased recumbency time), with decreased amount of skin lesions also associated with lower severity class for tail lesions. They also showed decreased CORT/DHEA ratio, potentially suggesting a beneficial effect of LaEO. Inhalation of LaEO significantly affected the nasal pig microbiome by reducing its diversity. Overall, the study suggests how inhalation of Lavender essential oil may be capable of improving welfare in growing pigs, yet it is pivotal to consider the microbial modulatory capabilities of essential oils before exploiting them on larger scale.

Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa

The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical L-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using L-cysteine and/or L-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.

Antimicrobial and anti-virulence activities of 4-shogaol from grains of paradise against gram-negative bacteria: Integration of experimental and computational methods

ETHNOPHARMACOLOGICAL RELEVANCE

Bacterial resistance to antibiotics is a growing global concern, highlighting the urgent need for new antimicrobial candidates. Aframomum melegueta was traditionally used for combating urinary tract and soft tissue infections, which implies its potential as an antimicrobial agent.

AIM OF STUDY

This study was designed to explore the antibacterial and anti-virulence capabilities of 4-shogaol isolated from A. melegueta seeds versus gram-negative bacteria: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and the clinically important pathogen Pseudomonas aeruginosa.

MATERIALS AND METHODS

4-Shogeol was isolated from A. melegueta seeds and its MICs were determined for Acinetobacter baumannii (ATCC-17978), Pseudomonas aeruginosa (ATCC-27853), Klebsiella pneumoniae (ATCC-700603), and Serratia marcescens clinical isolate. The anti-efflux activity and effect on the bacterial cell membrane for the compound were evaluated. Furthermore, the anti-virulence activities of the compound were evaluated. The effects of 4-shogeol at sub-MIC on bacterial motility, biofilm formation, and production of virulent enzymes and pigments were assessed. The anti-quorum sensing activities of 4-shogeol were evaluated virtually and by quantification its effect on the expression of quorum sensing encoding genes. The in vivo protection assay was conducted to evaluate the effect of 4-shogaol on the P. aeruginosa capacity to induce pathogenesis in mice. Finally, the effect of shogaol-antibiotics combination was assessed.

RESULTS

The research revealed that 4-shogaol's antibacterial action primarily involves disrupting the bacterial cell membrane and efflux pumps. It also exhibited significant anti-virulence effects by reducing biofilm development and repressing virulence factors production, effectively protecting mice against P. aeruginosa infection. Furthermore, when combined with antibiotics, 4-shogaol demonstrated synergistic effects, leading to reduced minimum inhibitory concentrations (MICs) against P. aeruginosa. Its anti-virulence properties were linked to its ability to disrupt bacterial quorum sensing (QS) mechanisms, as evidenced by its interaction with QS receptors and downregulation of QS-related genes. Notably, in silico analysis indicated that 4-shogaol exhibited strong binding affinity to different P. aeruginosa QS targets.

CONCLUSION

These findings suggest that 4-shogaol holds promise as an effective anti-virulence agent that can be utilized in combination with antibiotics for treating severe infections caused by gram-positive bacteria.

SIRT1 downregulation in pneumonia is associated with an immature neutrophil response and increased disease severity

BACKGROUND

Pneumonia remains a common complication in trauma patients. Sirtuin 1 (SIRT1) is an anti-inflammatory NAD + -dependent deacetylase that has been shown to reduce the severity of ARDS in polymicrobial sepsis. The impact of SIRT1 in acute pneumonia, however, remains unknown. We hypothesized that SIRT1 deletion in pneumonia would worsen the inflammatory response and clinical severity, and that increased SIRT1 expression would be protective.

METHODS

Ten- to 14-week-old male and female SIRT1 knockout (S1KO) mice, SIRT1 overexpressor (S1OE) mice, and their wildtype (WT) littermates underwent intra-tracheal inoculation with Pseudomonas aeruginosa . Rectal temperature was recorded, SIRT1 lung protein was quantified by western blotting, Sirt1 mRNA was measured by qPCR, and lung leukocyte subpopulations were analyzed by flow cytometry. Data were analyzed by one-way ANOVA using Prism software.

RESULTS

Pneumonia created a functional SIRT1 knockdown in the lungs of WT mice by 4 hours, resulting in comparable SIRT1 levels and temperatures to the S1KO mice by 12 hours. Pneumonia also partially reduced SIRT1expression in S1OE mice, but S1OE mice still had improved thermoregulation 12 hours after pneumonia. In all groups, Sirt1 mRNA expression was not affected by infection. Sirtuin 1 deletion was associated with decreased neutrophil infiltration in the lung, as well as a shift toward a more immature neutrophil phenotype. SIRT1 deletion was also associated with decreased myeloperoxidase-positive neutrophils in the lungs following pneumonia, indicating decreased neutrophil activity. S1OE mice had no change in lung leukocyte subpopulations when compared to WT.

CONCLUSION

Pneumonia creates a functional SIRT1 knockdown in mice. SIRT1 deletion altered the early inflammatory cell response to pneumonia, resulting in a neutrophil response that would be less favorable for bacterial clearance. Despite overexpression of SIRT1, S1OE mice also developed low SIRT1 levels and exhibited only minimal improvement. This suggests increasing SIRT1 transcription is not sufficient to overcome pneumonia-induced downregulation and has implications for future treatment options. Targeting SIRT1 through increasing protein stability may promote a more efficient inflammatory cell response to pneumonia, thereby preventing subsequent lung injury.

Flip the switch: the role of FleQ in modulating the transition between the free-living and sessile mode of growth in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen causing chronic infections that are associated with the sessile/biofilm mode of growth rather than the free-living/planktonic mode of growth. The transcriptional regulator FleQ contributes to both modes of growth by functioning both as an activator and repressor and inversely regulating flagella genes associated with the planktonic mode of growth and genes contributing to the biofilm mode of growth. Here, we review findings that enhance our understanding of the molecular mechanism by which FleQ enables the transition between the two modes of growth. We also explore recent advances in the mechanism of action of FleQ to both activate and repress gene expression from a single promoter. Emphasis will be on the role of sigma factors, cyclic di-GMP, and the transcriptional regulator AmrZ in inversely regulating flagella and biofilm-associated genes and converting FleQ from a repressor to an activator.

Antimicrobial Activity of Trigonelline Hydrochloride Against Pseudomonas aeruginosa and Its Quorum-Sensing Regulated Molecular Mechanisms on Biofilm Formation and Virulence

Pseudomonas aeruginosa, a vivid biofilm-producing bacterium, is considered a dreadful opportunistic pathogen, and thus, management of biofilm-associated infections due to multidrug resistant strains by traditional drugs currently is of great concern. This study was aimed to assess the impact of trigonelline hydrochloride, a pyridine alkaloid, on P. aeruginosa PAO1, in search of an alternative therapeutant. The effect of trigonelline on colony morphology and motility was studied along with its role on biofilm and expression virulence factors. Trigonelline influenced the colony structure, motility, biofilm architecture, and the production of virulence factors in a dose-dependent manner. Alterations in quorum sending (QS)-regulated gene expression after treatment and molecular docking analysis for certain regulator proteins confirmed its effect on the QS-system network by affecting Las, Rhl, and Pqs signaling pathways and as possible molecular targets. Thus, trigonelline might be considered as a potential chemical lead to manage biofilm-associated pathogenesis or to develop other analogues with enhanced pharmacokinetic actions.

Immune-Related Molecules CD3G and FERMT3: Novel Biomarkers Associated with Sepsis

Sepsis ranks among the most common health problems worldwide, characterized by organ dysfunction resulting from infection. Excessive inflammatory responses, cytokine storms, and immune-induced microthrombosis are pivotal factors influencing the progression of sepsis. Our objective was to identify novel immune-related hub genes for sepsis through bioinformatic analysis, subsequently validating their specificity and potential as diagnostic and prognostic biomarkers in an animal experiment involving a sepsis mice model. Gene expression profiles of healthy controls and patients with sepsis were obtained from the Gene Expression Omnibus (GEO) and analysis of differentially expressed genes (DEGs) was conducted. Subsequently, weighted gene co-expression network analysis (WGCNA) was used to analyze genes within crucial modules. The functional annotated DEGs which related to the immune signal pathways were used for constructing protein-protein interaction (PPI) analysis. Following this, two hub genes, FERMT3 and CD3G, were identified through correlation analyses associated with sequential organ failure assessment (SOFA) scores. These two hub genes were associated with cell adhesion, migration, thrombosis, and T-cell activation. Furthermore, immune infiltration analysis was conducted to investigate the inflammation microenvironment influenced by the hub genes. The efficacy and specificity of the two hub genes were validated through a mice sepsis model study. Concurrently, we observed a significant negative correlation between the expression of CD3G and IL-1β and GRO/KC. These findings suggest that these two genes probably play important roles in the pathogenesis and progression of sepsis, presenting the potential to serve as more stable biomarkers for sepsis diagnosis and prognosis, deserving further study.

Understanding the effects of Haemophilus influenzae colonization on bronchiectasis: a retrospective cohort study

BACKGROUND

Bacterial colonization is an essential aspect of bronchiectasis. Although Haemophilus influenzae is a frequent colonizer in some regions, its clinical impacts are poorly understood. This study aimed to elucidate the impact of H. influenzae colonization in patients with bronchiectasis.

METHODS

This retrospective study screened adult patients diagnosed with bronchiectasis at a tertiary referral center between April 1, 2003, and May 16, 2021, in South Korea. Propensity score matching was used to match patients with and without H. influenzae colonization. We assessed the severity of bronchiectasis as per the bronchiectasis severity index, the incidence of exacerbation, differences in lung function, and all-cause mortality.

RESULTS

Out of the 4,453 patients with bronchiectasis, 79 (1.8%) were colonized by H. influenzae. After 1:2 propensity score matching, 78 and 154 patients were selected from the H. influenzae colonizer and non-colonizer groups, respectively. Although there were no significant differences between the groups regarding baseline demographics, patients colonized with H. influenzae had a higher bronchiectasis severity index (median 6 [interquartile range 4-8] vs. 4 [2-7], p = 0.002), associated with extensive radiographic involvement (52.2% vs. 37.2%, p = 0.045) and mild exacerbation without hospitalization (adjusted incidence rate ratio 0.15; 95% confidence interval 0.12-0.24). Lung function and mortality rates did not reveal significant differences, regardless of H. influenzae colonization.

CONCLUSION

H. influenzae colonization in bronchiectasis was associated with more severe disease and greater incidence of mild exacerbation, but not lung function and mortality. Attention should be paid to patients with bronchiectasis with H. influenzae colonization.

New Therapeutic Options in Pulmonal Diseases: Sphingolipids and Modulation of Sphingolipid Metabolism

Sphingolipids are crucial molecules in the respiratory airways. As in most other tissues and organs, in the lung sphingolipids play an essential role as structural constituents as they regulate barrier function and fluidity of cell membranes. A lung-specific feature is the occurrence of sphingolipids as minor structural components in the surfactant. However, sphingolipids are also key signaling molecules involved in airway cell signaling and their dynamical formation and metabolism are important for normal lung physiology. Dysregulation of sphingolipid metabolism and signaling is involved in altering lung tissue and initiates inflammatory processes promoting the pathogenesis of pulmonal diseases including cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and asthma.In the present review, the important role of specific sphingolipid species in pulmonal diseases will be discussed. Only such an understanding opens up the possibility of developing new therapeutic strategies with the aim of correcting the imbalance in sphingolipid metabolism and signaling. Such delivery strategies have already been studied in animal models of these lung diseases, demonstrating that targeting the sphingolipid profile represents new therapeutic opportunities for lung disorders.

The Anti-Virulence Activities of the Antihypertensive Drug Propranolol in Light of Its Anti-Quorum Sensing Effects against Pseudomonas aeruginosa and Serratia marcescens

The development of bacterial resistance is an increasing global concern that requires discovering new antibacterial agents and strategies. Bacterial quorum sensing (QS) systems play important roles in controlling bacterial virulence, and their targeting could lead to diminishing bacterial pathogenesis. In this context, targeting QS systems without significant influence on bacterial growth is assumed as a promising strategy to overcome resistance development. This study aimed at evaluating the anti-QS and anti-virulence activities of the β-adrenoreceptor antagonist propranolol at sub-minimal inhibitory concentrations (sub-MIC) against two Gram-negative bacterial models Pseudomonas aeruginosa and Serratia marcescens. The effect of propranolol on the expression of QS-encoding genes was evaluated. Additionally, the affinity of propranolol to QS receptors was virtually attested. The influence of propranolol at sub-MIC on biofilm formation, motility, and production of virulent factors was conducted. The outcomes of the propranolol combination with different antibiotics were assessed. Finally, the in vivo protection assay in mice was performed to assess propranolol's effect on lessening the bacterial pathogenesis. The current findings emphasized the significant ability of propranolol at sub-MIC to reduce the formation of biofilms, motility, and production of virulence factors. In addition, propranolol at sub-MIC decreased the capacity of tested bacteria to induce pathogenesis in mice. Furthermore, propranolol significantly downregulated the QS-encoding genes and showed significant affinity to QS receptors. Finally, propranolol at sub-MIC synergistically decreased the MICs of different antibiotics against tested bacteria. In conclusion, propranolol might serve as a plausible adjuvant therapy with antibiotics for the treatment of serious bacterial infections after further pharmacological and pharmaceutical studies.

Alveolar macrophage modulation via the gut-lung axis in lung diseases

Several studies have demonstrated great potential implications for the gut-lung axis in lung disease etiology and treatment. The gut environment can be influenced by diet, metabolites, microbiotal composition, primary diseases, and medical interventions. These changes modulate the functions of alveolar macrophages (AMs) to shape the pulmonary immune response, which greatly impacts lung health. The immune modulation of AMs is implicated in the pathogenesis of various lung diseases. However, the mechanism of the gut-lung axis in lung diseases has not yet been determined. This mini-review aimed to shed light on the critical nature of communication between the gut and AMs during the development of pulmonary infection, injury, allergy, and malignancy. A better understanding of their crosstalk may provide new insights into future therapeutic strategies targeting the gut-AM interaction.

Discovery of highly neutralizing human antibodies targeting Pseudomonas aeruginosa

Drug-resistant Pseudomonas aeruginosa (PA) poses an emerging threat to human health with urgent need for alternative therapeutic approaches. Here, we deciphered the B cell and antibody response to the virulence-associated type III secretion system (T3SS) in a cohort of patients chronically infected with PA. Single-cell analytics revealed a diverse B cell receptor repertoire directed against the T3SS needle-tip protein PcrV, enabling the production of monoclonal antibodies (mAbs) abrogating T3SS-mediated cytotoxicity. Mechanistic studies involving cryoelectron microscopy identified a surface-exposed C-terminal PcrV epitope as the target of highly neutralizing mAbs with broad activity against drug-resistant PA isolates. These anti-PcrV mAbs were as effective as treatment with conventional antibiotics in vivo. Our study reveals that chronically infected patients represent a source of neutralizing antibodies, which can be exploited as therapeutics against PA.

DnaJ-induced miRNA-146a negatively regulates the expression of IL-8 in macrophages

As a member of the damage-associated molecular patterns, heat shock proteins (HSPs) are widely recognized for their role in initiating innate immune responses. These highly conserved proteins are expressed ubiquitously in both prokaryotes and eukaryotes. In this study, our aim was to investigate how DnaJ, a HSP40 homolog derived from Pseudomonas aeruginosa (P. aeruginosa), influences the regulation of IL-8 expression in macrophages. Treatment with DnaJ served as a stimulus, inducing a more robust expression of IL-8 compared to other HSP homologs, including DnaK, GroEL, and HtpG. This effect was achieved through the activation of the NF-κB signaling pathway. Interestingly, DnaJ treatment also significantly increased the expression of microRNA-146a (miR-146a), which appears to play a role in modulating the expression of innate defense genes. As a consequence, pre-treatment with DnaJ led to a reduction in the extent of IL-8 induction in response to P. aeruginosa treatment. Notably, this reduction was counteracted by transfection of a miR-146a inhibitor, highlighting the involvement of miR-146a in P. aeruginosa-mediated induction of IL-8 expression. Therefore, this study uncovers the role of DnaJ in triggering the expression of miR-146a, which, in turn, modulates the excessive expression of IL-8 induced by P. aeruginosa infection.

A score to predict Pseudomonas aeruginosa infection in older patients with community-acquired pneumonia

BACKGROUND

In Thailand, the incidence of community-acquired pseudomonal pneumonia among 60- to 65-year-olds ranges from 10.90% to 15.51%, with a mortality rate of up to 19.00%. Antipseudomonal agents should be selected as an empirical treatment for elderly patients at high risk for developing this infection. The purpose of this study was to identify risk factors and develop a risk predictor for Pseudomonas aeruginosa infection in older adults with community-acquired pneumonia (CAP).

METHODS

A retrospective data collection from an electronic database involved the elderly hospitalized patients with P. aeruginosa- and non-P. aeruginosa-causing CAP, admitted between January 1, 2016, and June 30, 2021. Risk factors for P. aeruginosa infection were analysed using logistic regression, and the instrument was developed by scoring each risk factor based on the beta coefficient and evaluating discrimination and calibration using the area under the receiver operating characteristic curve (AuROC) and observed versus predicted probability (E/O) ratio.

RESULTS

The inclusion criteria were met by 81 and 104 elderly patients diagnosed with CAP caused by P. aeruginosa and non-P. aeruginosa, respectively. Nasogastric (NG) tube feeding (odd ratios; OR = 40.68), bronchiectasis (B) (OR = 4.13), immunocompromised condition (I) (OR = 3.76), and other chronic respiratory illnesses (r) such as atelectasis, pulmonary fibrosis, and lung bleb (OR = 2.61) were the specific risk factors for infection with P. aeruginosa. The "60-B-r-I-NG" risk score was named after the 4 abbreviated risk variables and found to have good predicative capability (AuROC = 0.77) and accuracy comparable to or near true P. aeruginosa infection (E/O = 1). People who scored at least two should receive empirically antipseudomonal medication.

CONCLUSIONS

NG tube feeding before admission, bronchiectasis, immunocompromisation, atelectasis, pulmonary fibrosis and lung bleb were risk factors for pseudomonal CAP in the elderly. The 60-B-r-I-NG was developed for predicting P. aeruginosa infection with a high degree of accuracy, equal to or comparable to the existing P. aeruginosa infection. Antipseudomonal agents may be started in patients who are at least 60 years old and have a score of at least 2 in order to lower mortality and promote the appropriate use of these medications.

Dual-action gallium-flavonoid compounds for combating Pseudomonas aeruginosa infection

The opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa) causes infections that are difficult to treat, which is due to the bacterial natural resistance to antibiotics. The bacterium is also able to form a biofilm that protects the bacterium from clearance by the human immune system and leads to chronic infection. Herein, we synthesized and characterized a novel gallium compound that interferes with both the iron metabolism and quorum sensing system of P. aeruginosa to achieve a significant bactericidal activity. The compound could substantially reduce the secretion of bacterial virulence factors as well as eliminate biofilm formation. Integrative omics analysis indicates that this compound can significantly disturb the gene transcription and metabolism of P. aeruginosa. The effectiveness of the gallium compound was further validated in mammalian cell and murine skin infection models. Our study offers a new strategy to design new gallium-based antimicrobials to combat P. aeruginosa infection.

Using model systems to unravel host-Pseudomonas aeruginosa interactions

Using model systems in infection biology has led to the discoveries of many pathogen-encoded virulence factors and critical host immune factors to fight pathogenic infections. Studies of the remarkable Pseudomonas aeruginosa bacterium that infects and causes disease in hosts as divergent as humans and plants afford unique opportunities to shed new light on virulence strategies and host defence mechanisms. One of the rationales for using model systems as a discovery tool to characterise bacterial factors driving human infection outcomes is that many P. aeruginosa virulence factors are required for pathogenesis in diverse different hosts. On the other side, many host signalling components, such as the evolutionarily conserved mitogen-activated protein kinases, are involved in immune signalling in a diverse range of hosts. Some model organisms that have less complex immune systems also allow dissection of the direct impacts of innate immunity on host defence without the interference of adaptive immunity. In this review, we start with discussing the occurrence of P. aeruginosa in the environment and the ability of this bacterium to cause disease in various hosts as a natural opportunistic pathogen. We then summarise the use of some model systems to study host defence and P. aeruginosa virulence.

Proteomic analysis of ceftazidime and meropenem-exposed Pseudomonas aeruginosa ATCC 9027

BACKGROUND

Pseudomonas aeruginosa is well known for its intrinsic ability to resist a wide range of antibiotics, thus complicates treatment. Thus, understanding the response of the pathogen to antibiotics is important for developing new therapies. In this study, proteomic response of P. aeruginosa to the commonly used anti-pseudomonas antibiotics, ceftazidime (Caz) and meropenem (Mem) was investigated.

METHODS

P. aeruginosa ATCC 9027, an antibiotic-susceptible strain, was exposed to sub-MIC values of antibiotics either Caz or Mem for 14 days to obtain E1 strains and then cultured in antibiotic-free environments for 10 days to obtain E2 strains. Proteomes of the initial and E1, E2 strains were identified and comparatively analyzed using isobaric tags for relative and absolute quantitation (iTRAQ) in cooperation with nano LC-MS/MS. Noted up and down-regulated proteins were confirmed with quantitative reverse transcriptase PCR (qRT-PCR).

RESULTS

Overall, 1039 and 1041 proteins were identified in Caz and Mem-exposed strains, respectively. Upon antibiotic exposure, there were 7-10% up-regulated (Caz: 71, Mem: 85) and down-regulated (Caz: 106, Mem: 69) proteins (1.5-fold change cut-off). For both Caz and Mem, the DEPs were primarily the ones involved in metabolic process, membrane, virulence, protein synthesis, and antibiotic resistance in which proteins involved in antibiotics resistance tended to be up-regulated while proteins involved in protein synthesis and metabolic process were down-regulated. Noted proteins included beta-lactamase AmpC which was up-regulated and OprD which was down-regulated in both the antibiotic-exposed strains. Besides, biofilm formation related proteins TssC1 and Hcp1 in Caz- exposed strains and the membrane/ periplasmic proteins Azu and PagL in Mem-exposed strains were found significantly down-regulated. qRT-PCR results confirmed the expression change of AmpC, Hcp1 and OprD proteins.

CONCLUSION

Exposure of Pseudomonas aeruginosa to sub-MIC values of Caz and Mem resulted in around 10% change in its proteome. Not only proteins with confirmed roles in antibiotic resistance mechanisms changed their expression but also virulence- associated proteins. Both Caz and Mem response involved up-regulation of AmpC and down-regulation of OprD. While TssC1 and Hcp1 were responsible for Caz response, Azu and PagL were more likely involved in Mem response.

Relocating Glyceryl Trinitrate as an Anti-Virulence Agent against Pseudomonas aeruginosa and Serratia marcescens: Insights from Molecular and In Vivo Investigations

The problem of antibiotic resistance is a global critical public health concern. In light of the threat of returning to the pre-antibiotic era, new alternative approaches are required such as quorum-sensing (QS) disruption and virulence inhibition, both of which apply no discernible selective pressure on bacteria, therefore mitigating the potential for the development of resistant strains. Bearing in mind the significant role of QS in orchestrating bacterial virulence, disrupting QS becomes essential for effectively diminishing bacterial virulence. This study aimed to assess the potential use of sub-inhibitory concentration (0.25 mg/mL) of glyceryl trinitrate (GTN) to inhibit virulence in Serratia marcescens and Pseudomonas aeruginosa. GTN could decrease the expression of virulence genes in both tested bacteria in a significant manner. Histopathological study revealed the ability of GTN to alleviate the congestion in hepatic and renal tissues of infected mice and to reduce bacterial and leukocyte infiltration. This study recommends the use of topical GTN to treat topical infection caused by P. aeruginosa and S. marcescens in combination with antibiotics.

Murepavadin induces envelope stress response and enhances the killing efficacies of β-lactam antibiotics by impairing the outer membrane integrity of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that can cause a variety of acute and chronic infections. The bacterium is highly resistant to numerous antibiotics. Murepavadin is a peptidomimetic antibiotic that blocks the function of P. aeruginosa lipopolysaccharide (LPS) transport protein D (LptD), thus inhibiting the insertion of LPS into the outer membrane. In this study, we demonstrated that sublethal concentrations of murepavadin enhance the bacterial outer membrane permeability. Proteomic analyses revealed the alteration of protein composition in bacterial inner and outer membranes following murepavadin treatment. The antisigma factor MucA was upregulated by murepavadin. In addition, the expression of the sigma E factor gene algU and the alginate synthesis gene algD was induced by murepavadin. Deletion of the algU gene reduces bacterial survival following murepavadin treatment, indicating a role of the envelope stress response in bacterial tolerance. We further demonstrated that murepavadin enhances the bactericidal activities of β-lactam antibiotics by promoting drug influx across the outer membrane. In a mouse model of acute pneumonia, the murepavadin-ceftazidime/avibactam combination showed synergistic therapeutic effect against P. aeruginosa infection. In addition, the combination of murepavadin with ceftazidime/avibactam slowed down the resistance development. In conclusion, our results reveal the response mechanism of P. aeruginosa to murepavadin and provide a promising antibiotic combination for the treatment of P. aeruginosa infections.IMPORTANCEThe ever increasing resistance of bacteria to antibiotics poses a serious threat to global public health. Novel antibiotics and treatment strategies are urgently needed. Murepavadin is a novel antibiotic that blocks the assembly of lipopolysaccharide (LPS) into the Pseudomonas aeruginosa outer membrane by inhibiting LPS transport protein D (LptD). Here, we demonstrated that murepavadin impairs bacterial outer membrane integrity, which induces the envelope stress response. We further found that the impaired outer membrane integrity increases the influx of β-lactam antibiotics, resulting in enhanced bactericidal effects. In addition, the combination of murepavadin and a β-lactam/β-lactamase inhibitor mixture (ceftazidime/avibactam) slowed down the resistance development of P. aeruginosa. Overall, this study demonstrates the bacterial response to murepavadin and provides a new combination strategy for effective treatment.

The Association between Early Gram-Negative Bacteria in Tracheal Aspirate Cultures and Severe Bronchopulmonary Dysplasia among Extremely Preterm Infants Requiring Prolonged Ventilation

OBJECTIVE

The study aimed to evaluate the association between bronchopulmonary dysplasia (BPD) development at 36 weeks' postmenstrual age (PMA) and Gram-negative bacteria in tracheal aspirate cultures among extremely preterm infants.

STUDY DESIGN

This study has a retrospective cohort. Patients were 155 infants aged less than or equal to 26 gestational weeks who were admitted to the neonatal intensive care unit of Osaka Women's and Children's Hospital from 2009 to 2018. Primary outcome was respiratory outcomes expressed as BPD development.Multivariable logistic regression analysis was used to identify neonatal and bacterial factors associated with BPD.

RESULTS

After adjusting for gestational age, birth weight, sex, chorioamnionitis, Gram-positive cocci (GPC) and Gram-negative rods (GNRs) in tracheal aspirate cultures within 28 days after birth, GNRs were significantly associated with BPD development (odds ratio [OR]: 3.88, 95% confidence interval [CI]: 1.68-8.94). In contrast, GPCs were not associated with BPD development (OR: 0.47, 95% CI: 0.05-1.61).

CONCLUSION

Gram-negative bacteria in tracheal cultures within 28 days of birth are associated with BPD development in infants aged less than or equal to 26 gestational weeks.

KEY POINTS

· BPD is a factor for morbidity in extremely preterm infants.. · Respiratory infection is an adverse outcome of BPD.. · GNRs in tracheal cultures soon after birth disturb BPD development.. · GPC was not associated with BPD development..

Mitochondrial Dysfunction in Bacterial Infections

Mitochondria are critical in numerous cellular processes, including energy generation. Bacterial pathogens target host cell mitochondria through various mechanisms to disturb the host response and improve bacterial survival. We review recent advances in the understanding of how bacteria cause mitochondrial dysfunction through perturbations in mitochondrial cell-death pathways, energy production, mitochondrial dynamics, mitochondrial quality control, DNA repair, and the mitochondrial unfolded protein response. We also briefly highlight possible therapeutic approaches aimed at restoring the host mitochondrial function as a novel strategy to enhance the host response to bacterial infection.