Current Knowledge and Future Directions in Developing Strategies to Combat Pseudomonas aeruginosa Infection

Uncovering the potentiality of quinazoline derivatives against Pseudomonas aeruginosa with antimicrobial synergy and SAR analysis

Antimicrobial resistance has emerged as a covert global health crisis, posing a significant threat to humanity. If left unaddressed, it is poised to become the foremost cause of mortality worldwide. Among the multitude of resistant bacterial pathogens, Pseudomonas aeruginosa, a Gram-negative, facultative bacterium, has been responsible for mild to deadly infections. It is now enlisted as a global critical priority pathogen by WHO. Urgent measures are required to combat this formidable pathogen, necessitating the development of novel anti-pseudomonal drugs. To confront this pressing issue, we conducted an extensive screening of 3561 compounds from the ChemDiv library, resulting in the discovery of potent anti-pseudomonal quinazoline derivatives. Among the identified compounds, IDD-8E has emerged as a lead molecule, exhibiting exceptional efficacy against P. aeruginosa while displaying no cytotoxicity. Moreover, IDD-8E demonstrated significant pseudomonal killing, disruption of pseudomonal biofilm and other anti-bacterial properties comparable to a well-known antibiotic rifampicin. Additionally, IDD-8E's synergy with different antibiotics further strengthens its potential as a powerful anti-pseudomonal agent. IDD-8E also exhibited significant antimicrobial efficacy against other ESKAPE pathogens. Moreover, we elucidated the Structure-Activity-Relationship (SAR) of IDD-8E targeting the essential WaaP protein in P. aeruginosa. Altogether, our findings emphasize the promise of IDD-8E as a clinical candidate for novel anti-pseudomonal drugs, offering hope in the battle against antibiotic resistance and its devastating impact on global health.

Nanocomposites against Pseudomonas aeruginosa biofilms: Recent advances, challenges, and future prospects

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that causes life-threatening and persistent infections in immunocompromised patients. It is the culprit behind a variety of hospital-acquired infections owing to its multiple tolerance mechanisms against antibiotics and disinfectants. Biofilms are sessile microbial aggregates that are formed as a result of the cooperation and competition between microbial cells encased in a self-produced matrix comprised of extracellular polymeric constituents that trigger surface adhesion and microbial aggregation. Bacteria in biofilms exhibit unique features that are quite different from planktonic bacteria, such as high resistance to antibacterial agents and host immunity. Biofilms of P. aeruginosa are difficult to eradicate due to intrinsic, acquired, and adaptive resistance mechanisms. Consequently, innovative approaches to combat biofilms are the focus of the current research. Nanocomposites, composed of two or more different types of nanoparticles, have diverse therapeutic applications owing to their unique physicochemical properties. They are emerging multifunctional nanoformulations that combine the desired features of the different elements to obtain the highest functionality. This review assesses the recent advances of nanocomposites, including metal-, metal oxide-, polymer-, carbon-, hydrogel/cryogel-, and metal organic framework-based nanocomposites for the eradication of P. aeruginosa biofilms. The characteristics and virulence mechanisms of P. aeruginosa biofilms, as well as their devastating impact and economic burden are discussed. Future research addressing the potential use of nanocomposites as innovative anti-biofilm agents is emphasized. Utilization of nanocomposites safely and effectively should be further strengthened to confirm the safety aspects of their application.

Unraveling the immunopotentiation of P. aeruginosa PAPI-1 encoded pilin: From immunoinformatics survey to active immunization

For protection against Pseudomonas aeruginosa strains, a number of vaccine candidates have been introduced thus far. However, despite significant attempts in recent years, there are currently no effective immunogenic Bacteria components against this pathogen on the market. P. aeruginosa encoding a number of different virulence characteristics, as well as the rapid growth in multiple drug-resistant forms, has raised numerous health issues throughout the world. This pathogen expresses three different subtypes of T4P, including IVa, IVb, and Tad which are involved in various cellular processes. Highly virulent strains of P. aeruginosa can encode well-conserved PAPI-1 associated PilS2 pilus. Designing an efficient pili-based immunotherapy approach targeting P. aeruginosa pilus has remained controversial due to the variability heterogeneousness and hidden well-preserved binding site of T4aP and no approved human study is commercially based on IVa pilin. In this investigation, for the first time, through analytical immunoinformatics, we designed an effective chimeric PilS2 immunogen against numerous clinically important P. aeruginosa strains. Through active immunization against the extremely conserved region of the chimeric PilS2 pilin, we showed that PilS2 chimeric pilin whether administered alone or formulated with alum as an adjuvant could substantially stimulate humoral immunological responses in BALB/c mice. Based on these findings, we conclude that PilS2 pilin is therapeutically effective against a variety of highly virulent strains of P. aeruginosa and can act as a new immunogen for more research towards the creation of efficient immunotherapy techniques against the P. aeruginosa as a dexterous pathogen.

Role of Relebactam in the Antibiotic Resistance Acquisition in Pseudomonas aeruginosa: In Vitro Study

BACKGROUND

Pseudomonas aeruginosa shows resistance to several antibiotics and often develops such resistance during patient treatment.

OBJECTIVE

Develop an in vitro model, using clinical isolates of P. aeruginosa, to compare the ability of the imipenem and imipenem/relebactam to generate resistant mutants to imipenem and to other antibiotics. Perform a genotypic analysis to detect how the selective pressure changes their genomes.

METHODS

The antibiotics resistance was studied by microdilution assays and e-test, and the genotypic study was performed by NGS.

RESULTS

The isolates acquired resistance to imipenem in an average of 6 days, and to imipenem/relebactam in 12 days (p value = 0.004). After 30 days of exposure, 75% of the isolates reached a MIC > 64 mg/L for imipenem and 37.5% for imipenem/relebactam (p value = 0.077). The 37.5% and the 12.5% imipenem/relebactam mutants developed resistance to piperacillin/tazobactam and ceftazidime, respectively, while the 87.5% and 37.5% of the imipenem mutants showed resistance to these drugs (p value = 0.003, p value = 0.015). The main biological processes altered by the SNPs were the glycosylation pathway, transcriptional regulation, histidine kinase response, porins, and efflux pumps.

DISCUSSION

The addition of relebactam delays the generation of resistance to imipenem and limits the cross-resistance to other beta-lactams. The clinical relevance of this phenomenon, which has the limitation that it has been performed in vitro, should be evaluated by stewardship programs in clinical practice, as it could be useful in controlling multi-drug resistance in P. aeruginosa.

Primer Exchange Reaction (PER)-Based Construction of Scaffold for Low-Speed Centrifugation-Based Isolation and Quantitative Analysis of P. aeruginosa and its application in analyzing uterine secretions with intrauterine adhesion

Efficient isolation and sensitive quantification of Pseudomonas aeruginosa (P. aeruginosa) are crucial for identifying intrauterine infections and preventing the occurrence of intrauterine adhesion (IUA). However, traditional approaches, such as culture-based approach, are time-consuming. Herein, we constructed a detection scaffold by using primer exchange reaction (PER) that integrated the low-speed centrifugation-based isolation and sensitive quantification of target pathogenic bacteria. The established approach possesses several advantages, including (i) the approach is capable of simultaneous isolation and sensitive quantification of target bacteria; (ii) low-speed centrifugation or even manual equipment could be used to isolate target bacteria; and (iii) a low limit of detection was obtained as 54 cfu/mL. Based on this, the approach is a promising approach in analyzing P. aeruginosa from uterine secretions with IUA.

Anti-Biofilm Enzymes-Assisted Antibiotic Therapy against Burn Wound Infection by Pseudomonas aeruginosa

Pseudomonas aeruginosa can form biofilms at the site of burn wound, leading to infection and the failure of treatment regimens. The previous in vitro study demonstrated that a combination of the quorum-quenching enzyme AidHA147G and the extracellular matrix hydrolase PslG was effective in inhibiting biofilm and promoting antibiotic synergy. The aim of the present study was to evaluate the efficacy of this combination of enzymes in conjunction with tobramycin in treating burn wound infected with P. aeruginosa. The results showed that this treatment was effective in quorum-quenching and biofilm inhibition on infected wounds. Compared with the tobramycin treatment only, simultaneous treatment with the enzymes and antibiotics significantly reduced the severity of tissue damage, decreased the bacterial load, and reduced the expression of the inflammatory indicators myeloperoxidase (MPO) and malondialdehyde (MDA). Topical application of the enzymes also reduced the bacterial load and inflammation to some extent. These results indicate that the combined-enzyme approach is a potentially effective treatment for P. aeruginosa biofilm infections of burn wounds.

Genome-scale model of Pseudomonas aeruginosa metabolism unveils virulence and drug potentiation

Pseudomonas aeruginosa is one of the leading causes of hospital-acquired infections. To decipher the metabolic mechanisms associated with virulence and antibiotic resistance, we have developed an updated genome-scale model (GEM) of P. aeruginosa. The model (iSD1509) is an extensively curated, three-compartment, and mass-and-charge balanced BiGG model containing 1509 genes, the largest gene content for any P. aeruginosa GEM to date. It is the most accurate with prediction accuracies as high as 92.4% (gene essentiality) and 93.5% (substrate utilization). In iSD1509, we newly added a recently discovered pathway for ubiquinone-9 biosynthesis which is required for anaerobic growth. We used a modified iSD1509 to demonstrate the role of virulence factor (phenazines) in the pathogen survival within biofilm/oxygen-limited condition. Further, the model can mechanistically explain the overproduction of a drug susceptibility biomarker in the P. aeruginosa mutants. Finally, we use iSD1509 to demonstrate the drug potentiation by metabolite supplementation, and elucidate the mechanisms behind the phenotype, which agree with experimental results.

In-vitro activity of ceftolozane/tazobactam against Pseudomonas aeruginosa collected in the Study for Monitoring Antimicrobial Resistance Trends (SMART) between 2016 and 2019 in China

Ceftolozane/tazobactam (an antipseudomonal cephalosporin) in combination with a well-established β-lactamase inhibitor has not been approved to date in clinical practice in China. The aim of this study was to evaluate the in-vitro activity of ceftolozane/tazobactam and comparator agents against Pseudomonas aeruginosa with various resistance patterns. P. aeruginosa (n=2178) specimens were collected from multiple sources in seven geographic regions of China between 2016 and 2019. All isolates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and minimum inhibitory concentrations of various antimicrobial agents (ceftolozane/tazobactam, amikacin, tobramycin, ceftazidime, cefepime, colistin, levofloxacin, aztreonam, meropenem, imipenem and piperacillin/tazobactam) were determined using the Clinical and Laboratory Standards Institute's broth microdilution method. P. aeruginosa demonstrated considerably high rates of multi-drug resistance (MDR, 57.3%), extensive drug resistance (XDR, 43.5%) and difficult-to-treat resistance (DTR, 16.8%). The overall susceptibility of P. aeruginosa to ceftolozane/tazobactam was 81.9%, and ceftolozane/tazobactam showed diverse activity against the three resistant subsets, ranging from 28.5% against DTR P. aeruginosa to 68.9% against MDR P. aeruginosa. P. aeruginosa, MDR P. aeruginosa, XDR P. aeruginosa and DTR P. aeruginosa derived from the East (Jiangzhe area) region maintained significantly lower susceptibility to ceftolozane/tazobactam compared with P. aeruginosa, MDR P. aeruginosa, XDR P. aeruginosa and DTR P. aeruginosa from other regions. The susceptibility rates of P. aeruginosa isolated from diverse sources to ceftolozane/tazobactam were similar to isolates from bloodstream infections, with the highest being 88.6%. Compared with other antimicrobial agents, ceftolozane/tazobactam was more active than the β-lactams tested but was slightly less active than amikacin. Amikacin demonstrated the best activity against P. aeruginosa and the three resistant subsets. Ceftolozane/tazobactam demonstrated considerable in-vitro activity against P. aeruginosa, MDR P. aeruginosa, XDR P. aeruginosa and DTR P. aeruginosa, indicating that it could be an optional therapeutic agent against P. aeruginosa.

The opportunistic pathogen Pseudomonas aeruginosa exploits bacterial biotin synthesis pathway to benefit its infectivity

Pseudomonas aeruginosa is an opportunistic pathogen that predominantly causes nosocomial and community-acquired lung infections. As a member of ESKAPE pathogens, carbapenem-resistant P. aeruginosa (CRPA) compromises the limited therapeutic options, raising an urgent demand for the development of lead compounds against previously-unrecognized drug targets. Biotin is an important cofactor, of which the de novo synthesis is an attractive antimicrobial target in certain recalcitrant infections. Here we report genetic and biochemical definition of P. aeruginosa BioH (PA0502) that functions as a gatekeeper enzyme allowing the product pimeloyl-ACP to exit from fatty acid synthesis cycle and to enter the late stage of biotin synthesis pathway. In relative to Escherichia coli, P. aeruginosa physiologically requires 3-fold higher level of cytosolic biotin, which can be attributed to the occurrence of multiple biotinylated enzymes. The BioH protein enables the in vitro reconstitution of biotin synthesis. The repertoire of biotin abundance is assigned to different mouse tissues and/or organ contents, and the plasma biotin level of mouse is around 6-fold higher than that of human. Removal of bioH renders P. aeruginosa biotin auxotrophic and impairs its intra-phagosome persistence. Based on a model of CD-1 mice mimicking the human environment, lung challenge combined with systemic infection suggested that BioH is necessary for the full virulence of P. aeruginosa. As expected, the biotin synthesis inhibitor MAC13772 is capable of dampening the viability of CRPA. Notably, MAC13772 interferes the production of pyocyanin, an important virulence factor of P. aeruginosa. Our data expands our understanding of P. aeruginosa biotin synthesis relevant to bacterial infectivity. In particular, this study represents the first example of an extracellular pathogen P. aeruginosa that exploits biotin cofactor as a fitness determinant, raising the possibility of biotin synthesis as an anti-CRPA target.

Temporal Hierarchy and Context-Dependence of Quorum Sensing Signal in Pseudomonas aeruginosa

The Gram-negative bacterium Pseudomonas aeruginosa can cause infections in a broad range of hosts including plants, invertebrates and mammals and is an important source of nosocomial infections in humans. We were interested in how differences in the bacteria's nutritional environment impact bacterial communication and virulence factor production. We grew P. aeruginosa in 96 different conditions in BIOLOG Gen III plates and assayed quorum sensing (QS) signaling over the course of growth. We also quantified pyocyanin and biofilm production and the impact of sub-inhibitory exposure to tobramycin. We found that while 3-oxo-C12 homoserine lactone remained the dominant QS signal to be produced, timing of PQS production differed between media types. Further, whether cells grew predominantly as biofilms or planktonic cells was highly context dependent. Our data suggest that understanding the impact of the nutritional environment on the bacterium can lead to valuable insights into the link between bacterial physiology and pathology.

Draft Genome Sequence of the Multiple Antibiotic Resistant Pseudomonas aeruginosa PAO1-UB Subline

We report the draft genome sequence and antibiotic susceptibility of Pseudomonas aeruginosa strain PAO1-UB, a subline of the common reference strain PAO1. This strain was sequenced in order to provide information on the genome dynamics of PAO1 sublines and their genes conferring resistance to multiple antibiotics.

Antibiotic resistant bacteria: current situation and treatment options to accelerate the development of a new antimicrobial arsenal

INTRODUCTION

Antibiotic resistance is one of the biggest public health threats worldwide. Currently, antibiotic-resistant bacteria kill 700,000 people every year. These data represent the near future in which we find ourselves, a "post-antibiotic era" where the identification and development of new treatments are key. This review is focused on the current and emerging antimicrobial therapies which can solve this global threat.

AREAS COVERED

Through a literature search using databases such as Medline and Web of Science, and search engines such as Google Scholar, different antimicrobial therapies were analyzed, including pathogen-oriented therapy, phagotherapy, microbiota and antivirulent therapy. Additionally, the development pathways of new antibiotics were described, emphasizing on the potential advantages that the combination of a drug repurposing strategy with the application of mathematical prediction models could bring to solve the problem of AMRs.

EXPERT OPINION

This review offers several starting points to solve a single problem: reducing the number of AMR. The data suggest that the strategies described could provide many benefits to improve antimicrobial treatments. However, the development of new antimicrobials remains necessary. Drug repurposing, with the application of mathematical prediction models, is considered to be of interest due to its rapid and effective potential to increase the current therapeutic arsenal.

Enhanced Biosynthesis of Fatty Acids Contributes to Ciprofloxacin Resistance in Pseudomonas aeruginosa

Antibiotic-resistant Pseudomonas aeruginosa is insensitive to antibiotics and difficult to deal with. An understanding of the resistance mechanisms is required for the control of the pathogen. In this study, gas chromatography-mass spectrometer (GC-MS)-based metabolomics was performed to identify differential metabolomes in ciprofloxacin (CIP)-resistant P. aeruginosa strains that originated from P. aeruginosa ATCC 27853 and had minimum inhibitory concentrations (MICs) that were 16-, 64-, and 128-fold (PA-R16_CIP, PA-R64_CIP, and PA-R128_CIP, respectively) higher than the original value, compared to CIP-sensitive P. aeruginosa (PA-S). Upregulation of fatty acid biosynthesis forms a characteristic feature of the CIP-resistant metabolomes and fatty acid metabolome, which was supported by elevated gene expression and enzymatic activity in the metabolic pathway. The fatty acid synthase inhibitor triclosan potentiates CIP to kill PA-R128_CIP and clinically multidrug-resistant P. aeruginosa strains. The potentiated killing was companied with reduced gene expression and enzymatic activity and the returned abundance of fatty acids in the metabolic pathway. Consistently, membrane permeability was reduced in the PA-R and clinically multidrug-resistant P. aeruginosa strains, which were reverted by triclosan. Triclosan also stimulated the uptake of CIP. These findings highlight the importance of the elevated biosynthesis of fatty acids in the CIP resistance of P. aeruginosa and provide a target pathway for combating CIP-resistant P. aeruginosa.

Repressed Central Carbon Metabolism and Its Effect on Related Metabolic Pathways in Cefoperazone/Sulbactam-Resistant Pseudomonas aeruginosa

Metabolic shift and antibiotic resistance have been reported in Pseudomonas aeruginosa. However, the global metabolic characteristics remain largely unknown. The present study characterizes the central carbon metabolism and its effect on other metabolic pathways in cefoperazone-sulbactam (SCF)-resistant P. aeruginosa (PA-R_SCF). GC-MS-based metabolomics shows a repressed central carbon metabolism in PA-R_SCF, which is confirmed by measuring expression of genes and activity of enzymes in the metabolism. Furthermore, expression of the genes that encode the enzymes for the first step of fatty acid biosynthesis, glutamate metabolism, and electron transport chain is reduced, confirmed by their enzymatic activity assay, and the key enzyme for riboflavin metabolism is also reduced, indicating the decreased metabolic flux to the four related metabolic pathways. Moreover, the role of the reduced riboflavin metabolism, being related to ROS generation, in SCF resistance is explored. Exogenous H₂O₂ potentiates SCF-mediated killing in a dose-dependent manner, suggesting that the decreased ROS resulted from the reduced riboflavin metabolism that contributed to the resistance. These results indicate that the repressed central carbon metabolism and related riboflavin metabolism contribute to SCF resistance, but increasing ROS can restore SCF sensitivity. These findings characterize the repressed central carbon metabolism and its effect on other metabolic pathways as the global metabolic features in PA-R_SCF.

Glucose-Potentiated Amikacin Killing of Cefoperazone/Sulbactam Resistant Pseudomonas aeruginosa

Multidrug-resistant Pseudomonas aeruginosa has become one of global threat pathogens for human health due to insensitivity to antibiotics. Recently developed reprogramming metabolomics can identify biomarkers, and then, the biomarkers were used to revert the insensitivity and elevate antibiotic-mediated killing. Here, the methodology was used to study cefoperazone/sulbactam (SCF)-resistant P. aeruginosa (PA-R_SCF) and identified reduced glycolysis and pyruvate cycle, a recent clarified cycle providing respiratory energy in bacteria, as the most key enriched pathways and the depressed glucose as one of the most crucial biomarkers. Further experiments showed that the depression of glucose was attributed to reduction of glucose transport. However, exogenous glucose reverted the reduction to elevate intracellular glucose via activating glucose transport. The elevated glucose fluxed to the glycolysis, pyruvate cycle, and electron transport chain to promote downstream proton motive force (PMF). Consistently, exogenous glucose did not promote SCF-mediated elimination but potentiated aminoglycosides-mediated killing since aminoglycosides uptake is PMF-dependent, where amikacin was the best one. The glucose-potentiated amikacin-mediated killing was effective to both lab-evolved PA-R_SCF and clinical multidrug-resistant P. aeruginosa. These results reveal the depressed glucose uptake causes the reduced intracellular glucose and expand the application of metabolome-reprogramming on selecting conventional antibiotics to achieve the best killing efficacy.

A panel of diverse Pseudomonas aeruginosa clinical isolates for research and development

Objectives

Pseudomonas aeruginosa is a leading cause of community- and hospital-acquired infections. Successful treatment is hampered by its remarkable ability to rapidly develop resistance to antimicrobial agents, primarily through mutation. In response, WHO listed carbapenem-resistant P. aeruginosa as a Priority 1 (Critical) pathogen for research and development of new treatments. A key resource in developing effective countermeasures is access to diverse and clinically relevant strains for testing. Herein we describe a panel of 100 diverse P. aeruginosa strains to support this endeavour.

Methods

WGS was performed on 3785 P. aeruginosa isolates in our repository. Isolates were cultured from clinical samples collected from healthcare facilities around the world between 2003 and 2017. Core-genome MLST and high-resolution SNP-based phylogenetic analyses were used to select a panel of 100 strains that captured the genetic diversity of this collection. Antibiotic susceptibility testing was also performed using 14 clinically relevant antibiotics.

Results

This 100-strain diversity panel contained representative strains from 91 different STs, including genetically distinct strains from major epidemic clones ST-111, ST-235, ST-244 and ST-253. Seventy-one distinct antibiotic susceptibility profiles were identified ranging from pan-susceptible to pan-resistant. Known resistance alleles as well as the most prevalent mutations underlying the antibiotic susceptibilities were characterized for all isolates.

Conclusions

This panel provides a diverse and comprehensive set of P. aeruginosa strains for use in developing solutions to antibiotic resistance. The isolates and available metadata, including genome sequences, are available to industry, academia, federal and other laboratories at no additional cost.

Sub-Inhibitory Antibiotic Exposure and Virulence in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a prime opportunistic pathogen, one of the most important causes of hospital-acquired infections and the major cause of morbidity and mortality in cystic fibrosis lung infections. One reason for the bacterium's pathogenic success is the large array of virulence factors that it can employ. Another is its high degree of intrinsic and acquired resistance to antibiotics. In this review, we first summarise the current knowledge about the regulation of virulence factor expression and production. We then look at the impact of sub-MIC antibiotic exposure and find that the virulence-antibiotic interaction for P. aeruginosa is antibiotic-specific, multifaceted, and complex. Most studies undertaken to date have been in vitro assays in batch culture systems, involving short-term (<24 h) antibiotic exposure. Therefore, we discuss the importance of long-term, in vivo-mimicking models for future work, particularly highlighting the need to account for bacterial physiology, which by extension governs both virulence factor expression and antibiotic tolerance/resistance.

Inactivation of Nitrite-Dependent Nitric Oxide Biosynthesis Is Responsible for Overlapped Antibiotic Resistance between Naturally and Artificially Evolved Pseudomonas aeruginosa

Metabolic flexibility of Pseudomonas aeruginosa could lead to new strategies to combat bacterial infection. The present study used gas chromatography-mass spectrometry (GC-MS)-based metabolomics to investigate global metabolism in naturally and artificially evolved strains with cefoperazone-sulbactam (SCF) resistance (AP-R_CLIN-EVO and AP-R_LAB-EVO, respectively) from the same parent strain (AP-R_CLIN). Inactivation of the pyruvate cycle and nitric oxide (NO) biosynthesis was identified as characteristic features of SCF resistance in both evolved strains. Nitrite-dependent NO biosynthesis instead of an arginine-dependent NO pathway is responsible for the reduced NO, which is attributed to lower nitrite and electrons from the oxidation of NADH to NAD⁺ provided by the pyruvate cycle. Exogenous fumarate, NADH, nitrate, and nitrite promoted the NO level and thereby potentiated SCF-mediated killing. Unexpectedly, fumarate caused the elevation of nitrite, while nitrite/nitrate resulted in the increase of Cyt bc1 complex (providing electrons). These interesting findings indicate that the nitrite-dependent NO biosynthesis and the pyruvate cycle are mutual to promote NO metabolism. In addition, the NO-potentiated sensitivity to SCF was validated by NO donor sodium nitroprusside. These results reveal an endogenous NO-mediated SCF resistance and develop its reversion by metabolites in P. aeruginosa.

IMPORTANCE Infections with Pseudomonas aeruginosa have become a real concern among hospital-acquired infections, especially in cystic fibrosis patients and immunocompromised individuals. Control of the pathogen is challenging due to antibiotic resistance. Since bacterial metabolic state impacts sensitivity and resistance to antibiotics, exploring and disclosing bacterial metabolic mechanisms can be used to develop a metabolome-reprogramming approach to elevate bacterial sensitivity to antibiotics. Therefore, GC-MS-based metabolomics is used to explore the similarities and differences of metabolomes between naturally and artificially evolved cefoperazone-sulbactam (SCF)-resistant P. aeruginosa (AP-R_CLIN-EVO and AP-R_LAB-EVO, respectively) from the same parent strain (AP-R_CLIN). It identifies the depressed nitrite-dependent nitric oxide (NO) biosynthesis as the most overlapping characteristic feature between AP-R_CLIN-EVO and AP-R_LAB-EVO. This is because the pyruvate cycle fluctuates, thereby generating fewer NADH and providing fewer electrons for nitrite-dependent NO biosynthesis than the control. Interestingly, exogenous fumarate, NADH, nitrate, and nitrite as well as NO donor sodium nitroprusside promote NO generation to elevate sensitivity to SCF. These results highlight the way to understand metabolic mechanisms of antibiotic resistance and explore metabolic modulation to combat the bacterial pathogen.

Skin manifestations of Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

Pseudomonas aeruginosa is an opportunistic pathogen with considerable morbidity and mortality, particularly in vulnerable hosts. Skin manifestations are common, either representing local inoculation or secondary skin seeding following bloodstream infections. As patients with various predisposing conditions are expanding, we sought to review the most recent published evidence regarding epidemiology, risk factors and diagnosis of skin manifestations of P. aeruginosa.

RECENT FINDINGS

New data exist on epidemiology and diagnosis of skin infections; systemic infections are impacted by multidrug-resistance issues and host immune status.

SUMMARY

Green nail syndrome, toe web infection, hot tub folliculitis, hot hand-foot infection and external otitis are the most common infections originating from the skin per se. Local treatments are the cornerstone and prognosis is favorable in immunocompetent hosts. Ecthyma gangrenosum and P. aeruginosa subcutaneous nodules are usually associated with bloodstream infections and occur primarily in immunocompromised hosts. Necrotizing skin and soft tissue infections occur in diabetic, alcoholic and immunocompromised patients; management requires a multidisciplinary team with surgical approach. Burn wound infections may also be challenging, requiring a specialized team. In all the four latter types of P. aeruginosa skin infections portending significant morbidity and mortality, systemic antibiotics are an integral part of the treatment.

Eugenol-Functionalized Magnetite Nanoparticles Modulate Virulence and Persistence in Pseudomonas aeruginosa Clinical Strains

Efficient antibiotics to cure Pseudomonas aeruginosa persistent infections are currently insufficient and alternative options are needed. A promising lead is to design therapeutics able to modulate key phenotypes in microbial virulence and thus control the progression of the infectious process without selecting resistant mutants. In this study, we developed a nanostructured system based on Fe₃O₄ nanoparticles (NPs) and eugenol, a natural plant-compound which has been previously shown to interfere with microbial virulence when utilized in subinhibitory concentrations. The obtained functional NPs are crystalline, with a spherical shape and 10-15 nm in size. The subinhibitory concentrations (MIC 1/2) of the eugenol embedded magnetite NPs (Fe₃O₄@EUG) modulate key virulence phenotypes, such as attachment, biofilm formation, persister selection by ciprofloxacin, and the production of soluble enzymes. To our knowledge, this is the first report on the ability of functional magnetite NPs to modulate P. aeruginosa virulence and phenotypic resistance; our data highlights the potential of these bioactive nanostructures to be used as anti-pathogenic agents.

The Genetics of Prey Susceptibility to Myxobacterial Predation: A Review, Including an Investigation into Pseudomonas aeruginosa Mutations Affecting Predation by Myxococcus xanthus

Bacterial predation is a ubiquitous and fundamental biological process, which influences the community composition of microbial ecosystems. Among the best characterised bacterial predators are the myxobacteria, which include the model organism Myxococcus xanthus. Predation by M. xanthus involves the secretion of antibiotic metabolites and hydrolytic enzymes, which results in the lysis of prey organisms and release of prey nutrients into the extracellular milieu. Due to the generalist nature of this predatory mechanism, M. xanthus has a broad prey range, being able to kill and consume Gram-negative/positive bacteria and fungi. Potential prey organisms have evolved a range of behaviours which protect themselves from attack by predators. In recent years, several investigations have studied the molecular responses of a broad variety of prey organisms to M. xanthus predation. It seems that the diverse mechanisms employed by prey belong to a much smaller number of general "predation resistance" strategies. In this mini-review, we present the current state of knowledge regarding M. xanthus predation, and how prey organisms resist predation. As previous molecular studies of prey susceptibility have focussed on individual genes/metabolites, we have also undertaken a genome-wide screen for genes of Pseudomonas aeruginosa which contribute to its ability to resist predation. P. aeruginosa is a World Health Organisation priority 1 antibiotic-resistant pathogen. It is metabolically versatile and has an array of pathogenic mechanisms, leading to its prevalence as an opportunistic pathogen. Using a library of nearly 5,500 defined transposon insertion mutants, we screened for "prey genes", which when mutated allowed increased predation by a fluorescent strain of M. xanthus. A set of candidate "prey proteins" were identified, which shared common functional roles and whose nature suggested that predation resistance by P. aeruginosa requires an effective metal/oxidative stress system, an intact motility system, and mechanisms for de-toxifying antimicrobial peptides.

Pseudomonas aeruginosa elastase (LasB) as a therapeutic target

Why is P. aeruginosa LasB elastase an attractive target for antivirulence therapy and what is the state-of-the art in LasB inhibitor design and development?

Genome Sequence of Clinical Strain Pseudomonas aeruginosa NRD619

Here, we report the complete genome sequence of the multidrug-resistant (MDR) strain Pseudomonas aeruginosa NRD619, assembled via long- and short-read hybrid assembly. P. aeruginosa is a Gram-negative bacterial pathogen that is a significant public health burden. NRD619 was isolated from a left ventricular assist device (LVAD) draining sinus tract.

Here, we report the complete genome sequence of the multidrug-resistant (MDR) strain Pseudomonas aeruginosa NRD619, assembled via long- and short-read hybrid assembly. P. aeruginosa is a Gram-negative bacterial pathogen that is a significant public health burden. NRD619 was isolated from a left ventricular assist device (LVAD) draining sinus tract.