Pseudomonal Infections Research Articles

Alarming Prevalence of Nosocomial Pseudomonas aeruginosa among Patients with Infected Burn Wounds

Background: Recently, the prevalence of nosocomial Pseudomonas aeruginosa has become a concern due to its involvement in increased morbidity and mortality, especially those highly virulent strains associated with burn wounds in burn centers. Therefore, this cross-sectional study aimed to isolate and determine the prevalence of nosocomial Pseudomonas aeruginosa among burned inpatients. This study was carried out between September 2023 and March 2024. A total of 355 pus, purulent fluid and necrotic tissue swabs were obtained from burn victims with burns at the Burn Centers in Najaf City, Iraq. 85/355 (23.9%) of isolates under study were detected as Pseudomonas aeruginosa based on laboratory methods (microscopic, biochemical and culture). All test isolates appeared to grow optimally on cetrimide and chromium agar media, and colonies appeared green on these media when examined by the naked eye and greenish fluorescence under ultraviolet light. However, colonies on blood agar were bright and metallic, and the most common type of lysis was β-hemolysin followed by α-hemolysin. On Nutrient agar, most of the isolates were characterized by positive multi-pigment production 57/85 (67.1%), while 28/85 (32.9%) of the isolates were negative pigment production. Conclusion: The rate of virulent P. aeruginosa in the current study raises the degree of alarm, especially among burn patients because they do not have the means of defense that qualify them to resist this virulent pathogen. Also, the older age groups were more affected by it, which increases the levels of risk because elderly patients have weak immunity in addition to most of them being infected with other diseases such as diabetes, which increases the complications associated with burn infections. The impact of Pseudomonal infections on females in most age groups was one of the results of utmost importance and the real reasons behind it must be known. According to numerous studies and reports, the possession of this dangerous pathogen of multiple virulence factors such as its ability to form biofilms delays or prevents the patient's recovery and increases the likelihood of death in burn inpatients. Also, the possession of these virulent bacteria of a large genome makes them exceptionally adaptable and resistant to unfavorable environments.

Bacteriophage Therapy on an In Vitro Wound Model and Synergistic Effects in Combination with Beta-Lactam Antibiotics.

One of the primary opportunistic pathogens that can cause a wide range of diseases is Pseudomonas aeruginosa. This microorganism can become resistant to practically every antibacterial currently in use, including beta-lactam antibiotics. Its ability to proliferate as biofilm has been linked to, among other things, the failure of antimicrobial therapies. Due to a variety of virulence factors and host immune system modifications, P. aeruginosa is one of the most significant and common bacteria that colonize wounds and burns. A novel therapeutic option for treating these multidrug-resistant (MDR) bacterial infections is the combination of antibiotics and bacteriophages. This approach has been linked to improved biofilm penetration, a decreased selection of antibiotic and bacteriophage resistance, and an enhanced antibacterial impact. Combining the F1Pa bacteriophage and beta-lactam antibiotics reduced the viability of the mature biofilm of MDR P. aeruginosa strains and suppressed bacterial growth in vitro. F1Pa critically reduced the amount of biofilm that MDR P. aeruginosa clinical strains formed in the in vitro wound model. These findings highlight the bacteriophage F1Pa's therapeutic potential as a prophylactic topical treatment against MDR pseudomonal infections in wounds and burns.

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.

Clinical Outcomes of Ceftazidime-Avibactam versus Ceftolozane-Tazobactam in Managing Pseudomonal Infections in Patients Undergoing Renal Replacement Therapy.

This is a retrospective study conducted at our hospital between September 2018 and March 2022. Clinical cure was the primary endpoint, while microbiologic cure, 30-day recurrence, and 30-day mortality were the secondary endpoints. In total, 45 subjects met the inclusion criteria, with 25 receiving CZA and 20 receiving C/T. The median age was 69 (52-81) and 69 (61.5-83) years, respectively, while the median weight was 70 (55.5-81.5) and 66 (57-79) kg, respectively. Clinical cure was achieved in 12 (48%) subjects in the CZA group and 12 (60%) in the C/T group (p = 0.432). Of the 36 subjects who had repeated cultures, a microbiologic cure was achieved in 14/23 (60%) subjects and 10/13 (76.9%) subjects (p = 0.273). Thirty-day recurrence was reported in 3 (12%) cases in the CZA group and 6 (30%) in the C/T group (p = 0.082). The 30-day mortality was 13 (52%) subjects in the CZA group and 10 (50%) in the C/T group (p = 0.894). The median maintenance dose of CZA was 1.88 (0.94-3.75) g and 2.25 (1.5-2.25) g for C/T. Multivariate logistic regression analysis indicated that both drugs did not differ significantly in clinical cure. Bloodstream infection (BSI) (OR = 25, 95% CI: 1.63-411.7, p = 0.021) was the only independent factor associated with clinical cure in this population. Our findings indicated that C/T and CZA did not significantly differ in achieving clinical cure in patients with MDR PSA infections undergoing RRT. Larger clinical trials are needed to confirm our findings.

Enzyme-Linked Lipid Nanocarriers for Coping Pseudomonal Pulmonary Infection. Would Nanocarriers Complement Biofilm Disruption or Pave Its Road?

Cystic fibrosis (CF) is associated with pulmonary Pseudomonas aeruginosa infections persistent to antibiotics. To eradicate pseudomonal biofilms, solid lipid nanoparticles (SLNs) loaded with quorum-sensing-inhibitor (QSI, disrupting bacterial crosstalk), coated with chitosan (CS, improving internalization) and immobilized with alginate lyase (AL, destroying alginate biofilms) were developed. SLNs (140-205 nm) showed prolonged release of QSI with no sign of acute toxicity to A549 and Calu-3 cells. The CS coating improved uptake, whereas immobilized-AL ensured >1.5-fold higher uptake and doubled SLN diffusion across the artificial biofilm sputum model. Respirable microparticles comprising SLNs in carbohydrate matrix elicited aerodynamic diameters MMAD (3.54, 2.48 µm) and fine-particle-fraction FPF (65, 48%) for anionic and cationic SLNs, respectively. The antimicrobial and/or antibiofilm activity of SLNs was explored in Pseudomonas aeruginosa reference mucoid/nonmucoid strains as well as clinical isolates. The full growth inhibition of planktonic bacteria was dependent on SLN type, concentration, growth medium, and strain. OD measurements and live/dead staining proved that anionic SLNs efficiently ceased biofilm formation and eradicated established biofilms, whereas cationic SLNs unexpectedly promoted biofilm progression. AL immobilization increased biofilm vulnerability; instead, CS coating increased biofilm formation confirmed by 3D-time lapse confocal imaging. Incubation of SLNs with mature biofilms of P. aeruginosa isolates increased biofilm density by an average of 1.5-fold. CLSM further confirmed the binding and uptake of the labeled SLNs in P. aeruginosa biofilms. Considerable uptake of CS-coated SLNs in non-mucoid strains could be observed presumably due to interaction of chitosan with LPS glycolipids in the outer cell membrane of P. aeruginosa. The biofilm-destructive potential of QSI/SLNs/AL inhalation is promising for site-specific biofilm-targeted interventional CF therapy. Nevertheless, the intrinsic/extrinsic fundamentals of nanocarrier-biofilm interactions require further investigation.

In vitro and in vivo evaluation of the biofilm-degrading Pseudomonas phage Motto, as a candidate for phage therapy.

Infections caused by Pseudomonas aeruginosa are becoming increasingly difficult to treat due to the emergence of strains that have acquired multidrug resistance. Therefore, phage therapy has gained attention as an alternative to the treatment of pseudomonal infections. Phages are not only bactericidal but occasionally show activity against biofilm as well. In this study, we describe the Pseudomonas phage Motto, a T1-like phage that can clear P. aeruginosa infections in an animal model and also exhibits biofilm-degrading properties. The phage has a substantial anti-biofilm activity against strong biofilm-producing isolates (n = 10), with at least a twofold reduction within 24 h. To demonstrate the safety of using phage Motto, cytotoxicity studies were conducted with human cell lines (HEK 293 and RAW 264.7 macrophages). Using a previously established in vivo model, we demonstrated the efficacy of Motto in Caenorhabditis elegans, with a 90% survival rate when treated with the phage at a multiplicity of infection of 10.

Discovery of psoralen as a quorum sensing inhibitor suppresses Pseudomonas aeruginosa virulence

Pseudomonas aeruginosa is a common opportunistic pathogen with growing resistance and presents heightened treatment challenges. Quorum sensing (QS) is a cell-to-cell communication system that contributes to the production of a variety of virulence factors and is also related to biofilm formation of P. aeruginosa. Compared to traditional antibiotics which kill bacteria directly, the anti-virulence strategy by targeting QS is a promising strategy for combating pseudomonal infections. In this study, the QS inhibition potential of the compounds derived from the Traditional Chinese Medicines was evaluated by using in silico, in vitro, and in vivo analyses. The results showed that psoralen, a natural furocoumarin compound derived from Psoralea corylifolia L., was capable of simultaneously inhibiting the three main QS regulators, LasR, RhlR, and PqsR of P. aeruginosa. Psoralen had no bactericidal activity but could widely inhibit the production of extracellular proteases, pyocyanin, and biofilm, and the cell motilities of the model and clinical P. aeruginosa strains. RNA-sequencing and quantitative PCR analyses further demonstrated that a majority of QS-activated genes in P. aeruginosa were suppressed by psoralen. The supplementation of psoralen could protect Caenorhabditis elegans from P. aeruginosa challenge, especially for the hypervirulent strain PA14. Moreover, psoralen showed synergistic antibacterial effects with polymyxin B, levofloxacin, and kanamycin. In conclusions, this study identifies the anti-QS and antibiofilm effects of psoralen against P. aeruginosa strains and sheds light on the discovery of anti-pseudomonal drugs among Traditional Chinese Medicines.Key points• Psoralen derived from Psoralea corylifolia L. inhibits the virulence-related phenotypes of P. aeruginosa.• Psoralen simultaneously targets the three core regulators of P. aeruginosa QS system and inhibits the expression of a large part of downstream genes.• Psoralen protects C. elegans from P. aeruginosa challenge and enhances the susceptibility of P. aeruginosa to antibiotics.

Unveiling the potential of recently FDA-approved drugs as quorum sensing inhibitors against P. Aeruginosa using high-performance computational techniques

Through cell-to-cell communication, activation of efflux pumps, formation of biofilms, and other mechanisms, pseudomonas aeruginosa’s quorum sensing systems (QSS), notably the lasl/las-r system, contribute a vital role in the development of anti-microbial resistance (AMR). Identifying potential drugs against these targets could have significant implications for combating pseudomonal infections. The current study aims to identify promising recently FDA-approved drugs against lasl/las-r proteins. The ligands were selected from the FDA-approved drug lists of the last 5 years. Out of 202, 78 drugs were checked for interaction with lasl/las-r protein and 4 drugs revealed top binding conformations characterized by favorable energetic profiles within the active site of the las-r protein which were further assigned for 250-ns molecular dynamics (MD) simulation. The MD analysis confirmed the dynamical stability of brexanolone and oteseconazole with las-r protein. The root mean square deviation (RMSD), radius of gyration (Rg) and solvent-accessible surface area (SASA) analysis have indicated less deviation, more compactness of protein and less exposure of protein ligand complex to its surroundings as compared to the reference ligand-protein complex. The hydroxyl group in the oteseconazole whereas hydroxyl and ketone group in the brexanolone were responsible for hydrogen bonds with the active site residue of las r ptotein as indicated by ligand-protein contacts diagram. The binding energies per residue analysis revealed TYR-47 as the most contributing amino acid residue for interaction with oteseconazole and brexanolone. The identified drugs may be potential repurposing candidates against pseudomonal infections through inhibition of las-r protein. Communicated by Ramaswamy H. Sarma

Safety and Efficacy of Anakinra in Haemophagocytic Lymphohistiocytosis Associated with Acute Leukaemia

Haemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition in which immune hyperactivation and dysregulation results in a cytokine storm. It may be primary or secondary to infection, autoimmune disorders or malignancies (HLH-M). Lymphoma is the most widely described association in HLH-M; there is very limited data linking acute leukaemia and HLH. Current recommended treatments for HLH-M include steroids, IVIG and etoposide-containing regimens. In contrast, the recommended treatment in HLH- Macrophage activation syndrome is anti-IL1 directed therapy such as anakinra. In 2021 NHS England approved the use of anakinra to treat HLH of any cause, but the safety and efficacy data of anakinra in HLH-M is limited. We report a retrospective review of all patients diagnosed with HLH and acute leukaemia (AML) or acute lymphoblastic leukaemia (ALL) in a single London tertiary referral centre (University College London Hospitals NHS Foundation Trust (UCLH)), between 1 January2019 and 31 December 2022. We analysed electronic health records (EHR) of all patients diagnosed with ALL or AML and cross-referenced this with records of all patients referred to the UCLH HLH MDT. This identified 468 patients with acute leukaemia, of whom 13 (2.8%) were diagnosed with HLH. For diagnostic purposes, we utilised H scores (comprising laboratory and clinical parameters providing an HLH probability for each patient) using clinical and laboratory data collected from the EHR. HLH was diagnosed in patients with a clinical suspicion of HLH and an H score of >169. Patients were treated with various types of immunosuppressive therapy (IST). Twelve (92%) received anakinra, three (17%) of whom had anakinra monotherapy whilst the remainder had anakinra with steroids (38%), steroids and IVIG (15%), or steroids, IVIG and etoposide (8%). Anakinra was given intravenously in eleven patients and subcutaneously in one, with a mean daily dose of 4.6mg/kg. All patients required critical care input during their HLH treatment. Eight (62%) were admitted to intensive care unit (ICU) on diagnosis with HLH and required ventilatory and vasopressor support; the remainder were reviewed by critical care outreach. 92% patients had an initial rapid clinicopathological response following IST, becoming afebrile, reduction in oxygen requirement and haemodynamic stability seen within 24-72 hours. One patient (8%) had an initial clinical response to anakinra, methylprednisolone and IVIG triple therapy, but displayed subsequent rapid deterioration in the context of pseudomonal infection and died of multiorgan failure. Nine patients (69%) had no clinicopathological recurrence of HLH following initial treatment. Three (23%) had an initial clinical response to IST but had subsequent biochemical and clinical relapse of HLH. These patients all had relapsed/refractory disease on HLH recurrence. Only one (8%) patient died from HLH. Eight (62%) remain in remission from leukaemia at the end of the study period. Three patients (23%) died of refractory leukaemia, whilst a fourth patient is receiving palliative care for refractory disease. Although the link between HLH and lymphoma is well characterised, there is limited data on HLH in the context of acute leukaemia. In this case series, 2.8% of the patients treated with acute leukaemia developed HLH, which is comparable to the 3% for lymphoma quoted elsewhere. Although 92% of patients had microbiological or radiological evidence of infection on HLH diagnosis, many infections involved organisms not classically associated with HLH e.g. rhinovirus, indicating that the underlying leukaemia may play a central role in HLH-M pathogenesis. This is highlighted by the relapse of HLH which occurred alongside leukaemia relapse in three patients. Treatment responses and outcomes were favourable compared to the existing literature. Tamamyan et al reported an overall survival rate of 15% in 13 patients with HLH-M. Delavigne et al reported a three-month mortality rate of 36% in AML patients presenting with HLH during induction, compared to our figure of 23% for this time period and our overall survival rate of 62%. We believe this is the first case series demonstrating the effectiveness and high overall survival of HLH-M patients with concurrent leukaemia diagnosis using anakinra. Early treatment with anakinra alongside other immunosuppression may explain the trend towards improved outcomes in our cohort.

Mesenchymal Stem Cells and Regenerative Therapy with Bilateral Gracilis Flaps for Perineal Reconstruction of a Wound Infection in the Setting of Anal Squamous Cell Carcinoma.

Many patients are affected by HIV/AIDS, and these conditions are highly prevalent worldwide. Patients with HIV/AIDS can experience debilitating wound infections that often require flap reconstruction and become challenging for surgeons to treat. In the past 5 years, mesenchymal stem cells have been tested and used as regenerative therapy to promote the growth of tissues throughout the body because of their ability to successfully promote cellular mitogenesis. To the authors' knowledge, the use of mesenchymal stem cell grafting following necrosis of a myocutaneous gracilis flap (as part of perineal wound reconstruction) has never been reported in the literature.In addition, the use of mesenchymal stem cells and regenerative medicine combined in the setting of squamous cell carcinoma of the anus with prior radiation (along with comorbid AIDS) has not been previously documented.In this report, the authors outline the case of a 60-year-old patient who had a recipient bed (perineum) complication from prior radiation therapy. Complicating the clinical picture, the patient also developed a Pseudomonal organ space infection of the pelvis leading to the failure of a vertical rectus abdominis myocutaneous flap and myocutaneous gracilis flaps. As a result, the patient underwent serial operative debridements for source control, with the application of mesenchymal stem cells, fetal bovine dermis, porcine urinary bladder xenograft, and other regenerative medicine products, achieving a highly successful clinical outcome. A procedural description for future use and replication of this method is provided.

Alleviating the virulence of Pseudomonas aeruginosa and Staphylococcus aureus by ascorbic acid nanoemulsion

The high incidence of persistent multidrug resistant bacterial infections is a worldwide public health burden. Alternative strategies are required to deal with such issue including the use of drugs with anti-virulence activity. The application of nanotechnology to develop advanced Nano-materials that target quorum sensing regulated virulence factors is an attractive approach. Synthesis of ascorbic acid Nano-emulsion (ASC-NEs) and assessment of its activity in vitro against the virulence factors and its protective ability against pathogenesis as well as the effect against expression of quorum sensing genes of Pseudomonas aeruginosa and Staphylococcus aureus isolates. Ascorbic acid Nano-emulsion was characterized by DLS Zetasizer Technique, Zeta potential; Transmission Electron Microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The antibacterial activity of ASC-NEs was tested by the broth microdilution method and the activity of their sub-MIC against the expression of quorum sensing controlled virulence was investigated using phenotypic experiments and RT-PCR. The protective activity of ASC-NEs against P. aeruginosa as well as S. aureus pathogenesis was tested in vivo. Phenotypically, ASC-NEs had strong virulence inhibitory activity against the tested bacteria. The RT-PCR experiment showed that it exhibited significant QS inhibitory activity. The in vivo results showed that ASC-NEs protected against staphylococcal infection, however, it failed to protect mice against Pseudomonal infection. These results suggest the promising use of nanoformulations against virulence factors in multidrug resistant P. aeruginosa and S. aureus. However, further studies are required concerning the potential toxicity, clearance and phamacokinetics of the nanoformulations.

Piperacillin-tazobactam dosing in anuric acute kidney injury patients receiving continuous renal replacement therapy.

To determine appropriate dosing of piperacillin-tazobactam in critically ill patients receiving continuous renal replacement therapy (CRRT). The databases of PubMed, Embase, and ScienceDirect were searched. We used the Medical Subject Headings of "piperacillin-tazobactam," "CRRT," and "pharmacokinetics" or related terms or synonym to identify the studies for reviews. A one-compartment pharmacokinetic model was conducted to predict piperacillin levels for the initial 48 h of therapy. The pharmacodynamic target was 50% of free drug level above the minimum inhibitory concentration (MIC) and 4 times of the MIC. The dose that achieved at least 90% of the probability of target attainment was defined as an optimal dose. Our simulation study reveals that the dosing regimen of piperacillin-tazobactam 12 g/day is appropriate for treating Pseudomonal infection with KDIGO recommended effluent rate of 25-35 mL/kg/h. The MIC values of each setting were an important factor to design piperacillin-tazobactam dosing regimens. The Monte Carlo simulation can be a useful tool to evaluate drug dosing in critically ill acute kidney injury patients receiving CRRT when limited pharmacokinetic data are a concern. Clinical validation of these results is needed.

Formulation and Biological Evaluation of Quorum Sensing Inhibitor-Based Nanoemulsion against Resistant Pseudomonal Infections

Antimicrobial resistance has raised a serious concern due to the lack of therapeutics to control pathogenic infections. Pseudomonas aeruginosa is considered a multidrug-resistant pathogen and a leading cause of hospital-acquired infections. Anti-virulence approach mainly focuses on targeting bacterial virulence despite its growth and proves effective against such drug-resistant pathogens. In this study, we select a novel flavonoid compound, 7,8-dihydroxyflavone (DHF), which has been reported as a quorum sensing inhibitor (QSI) of P. aeruginosa, performed its in-silico studies to observe its binding affinity and potential interactions with the target protein (2UV0) and further developed it as a nano drug formulation (DHF-NF), and performed its in-vitro and in-vivo evaluation. The prepared DHF-NF was examined for its efficacy in the prevention of wound-associated surface infections of P. aeruginosa in rats. The DHF-NF was prepared by using homogenization and examined for several physical parameters. The prepared DHF-NF had a spherical shape and smooth topology. The microbiological assays demonstrated the inhibitory potential of DHF-NF in a dose-dependent manner. The histological analysis of Pseudomonas infected tissue of rat skin showed significant activity in animal group treated with DHF-NF as compared to control groups. The microbiological and in-vivo evaluation results revealed that the compound, DHF, showed strong inhibitory potential and suggest that the DHF-NF could be utilized as novel anti-QS and anti-biofilm therapeutics against Pseudomonal surface infections.

α-Terpineol synergizes with gentamicin to rescue Caenorhabditis elegans from Pseudomonas aeruginosa infection by attenuating quorum sensing-regulated virulence

AimsThis study scrutinized α-Terpineol (α-T) for its anti-virulence and anti-fouling potential against P. aeruginosa PAO1 in conjunction with gentamicin (GeN) using in-vitro, in-silico, and in-vivo approaches. Main methodsThe quorum quenching (QQ) potential of the drug combination was studied using a quorum sensing (QS) biosensor strain and tested for synergy using chequerboard and time-kill kinetics assays. The effect of α-T and GeN on bacterial motility, QS-regulated virulence factor production, and biofilm formation was assessed in P. aeruginosa PAO1 along with molecular docking analysis. The protective effects of α-T-GeN combination were also examined in a Caenorhabditis elegans infection model through slow-killing (SK) assays. Key findingsThe drug combination displayed synergy, enhanced QQ activity, and suppressed AHL production in PAO1. At sub-inhibitory concentrations, the drug combination suppressed the expression of genes regulating QS and pseudomonal virulence, thereby inhibiting the production of virulence factors in PAO1. The drug combination compromised all forms of pseudomonal motility, strongly inhibited biofilm formation, and successfully eradicated preformed biofilms. Based on these findings, it is concluded that GeN (alone) does not harbor any QQ properties, but enhances the QQ potential of α-T. Moreover, combinational treatment protected C. elegans from pseudomonal infection and improved survival rates by 73 % at 96 h. SignificanceFor the first time, the molecular mechanism responsible for the anti-QS activity of α-T was unraveled through a comprehensive investigation, thereby asserting its potential as an anti-virulent drug against P. aeruginosa.

Antimicrobial Treatment of Pseudomonas aeruginosa Severe Sepsis.

Pseudomonas aeruginosa is a pathogen often encountered in a healthcare setting. It has consistently ranked among the most frequent pathogens seen in nosocomial infections, particularly bloodstream and respiratory tract infections. Aside from having intrinsic resistance to many antibiotics, it rapidly acquires resistance to novel agents. Given the high mortality of pseudomonal infections generally, and pseudomonal sepsis particularly, and with the rise of resistant strains, treatment can be very challenging for the clinician. In this paper, we will review the latest evidence for the optimal treatment of P. aeruginosa sepsis caused by susceptible as well as multidrug-resistant strains including the difficult to treat pathogens. We will also discuss the mode of drug infusion, indications for combination therapy, along with the proper dosing and duration of treatment for various conditions with a brief discussion of the use of non-antimicrobial agents.

Green nail syndrome complicated by pseudomonal keratitis in a teenager with artificial nails.

Green nail syndrome (GNS) is a pseudomonal nail infection that presents with characteristic green nail discoloration. It typically affects patients with preexisting nail conditions or chronic exposure to wet environments but can also be seen with local trauma. Our patient presented with a pseudomonal corneal ulcer of the left eye and was incidentally found to have GNS, which developed after home artificial nail application. This unusual case of extensive pediatric GNS illustrates a rare and serious infectious complication of prolonged artificial nails.

In vivo, in vitro and molecular docking studies reveal the anti-virulence property of hispidulin against Pseudomonas aeruginosa through the modulation of quorum sensing

Pseudomonas aeruginosa is an audacious infectious agent involved in multiple persistent and incurable diseases in hosts through quorum sensing mediated pathways. Thus, compounds targeting quorum sensing (QS) can reduce the pathogenesis and virulence. The present study attempts to elucidate the QS inhibition properties of hispidulin against P. aeruginosa PAO1. Hispidulin (HPD) at its sub-inhibitory concentration (75 μg/ml) decreased violacein and pyocyanin pigment production of reporter bacteria and test bacteria to 81.92 ± 1.90 and 71.69 ± 3.46%, respectively. HPD supressed the virulence and biofilm development as similar to the positive control, baicalein. The pathogenesis of P. aeruginosa was effectively reduced in the infected worm model. The infected C. elegans showed 80.43% survival on the 6th day in presence of sub-MIC of HPD. In addition, HPD reduced the transcription of genes regulated by Las and Rhl networks including the receptor proteins and autoinducer producing genes which validated the anti-QS potential of the flavonoid. Computational studies revealed competitive binding of HPD with LasR protein and a weak interaction with RhlR. The results suggested the ability of HPD to block QS regulatory networks of P. aeruginosa. The potential lead obtained through this study can be utilized in the near future to design and develop anti-pathogenic agents to treat pseudomonal infections.

Chemical Composition and Antibacterial Activity of Liquid and Volatile Phase of Essential Oils against Planktonic and Biofilm-Forming Cells of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen causing life-threatening, hard-to-heal infections associated with the presence of a biofilm. Essential oils (EOs) are promising agents to combat pseudomonal infections because of the alleged antimicrobial activity of their volatile fractions and liquid forms. Therefore, the purpose of this paper was to evaluate the antibacterial efficacy of both volatile and liquid phases of seven EOs (thyme, tea tree, basil, rosemary, eucalyptus, menthol mint, lavender) against P. aeruginosa biofilm and planktonic cells with the use of a broad spectrum of analytical in vitro methods. According to the study results, the antibacterial activity of EOs in their liquid forms varied from that of the volatile fractions. Overall, liquid and volatile forms of rosemary EO and tea tree EO displayed significant antibiofilm effectiveness. The outcomes indicate that these particular EOs possess the potential to be used in the therapy of P. aeruginosa infections.

Gentamicin Augments the Quorum Quenching Potential of Cinnamaldehyde In Vitro and Protects Caenorhabditis elegans From Pseudomonas aeruginosa Infection.

The quorum sensing (QS) circuitry of Pseudomonas aeruginosa represents an attractive target to attenuate bacterial virulence and antibiotic resistance. In this context, phytochemicals harboring anti-virulent properties have emerged as an alternative medicine to combat pseudomonal infections. Hence, this study was undertaken to investigate the synergistic effects and quorum quenching (QQ) potential of cinnamaldehyde (CiNN) in combination with gentamicin (GeN) against P. aeruginosa. The QQ activity of this novel combination was evaluated using a QS reporter strain and synergism was studied using chequerboard assays. Further, the genotypic and phenotypic expression of pseudomonal virulence factors was examined alongside biofilm formation. The combination of CiNN and GeN exhibited synergy and promising anti-QS activity. This drug combination was shown to suppress AHL production and downregulate the expression of critical QS genes in P. aeruginosa PAO1. Molecular docking revealed strong interactions between the QS receptors and CiNN, asserting its QQ potential. Bacterial motility was compromised along with a significant reduction in pyocyanin (72.3%), alginate (58.7%), rhamnolipid (33.6%), hemolysin (82.6%), protease (70.9%), and elastase (63.9%) production. The drug combination successfully eradicated preformed biofilms and inhibited biofilm formation by abrogating EPS production. Our findings suggest that although GeN alone could not attenuate QS, but was able to augment the anti-QS potential of CiNN. To validate our results using an infection model, we quantified the survival rates of Caenorhabditis elegans following PAO1 challenge. The combination significantly rescued C. elegans from PAO1 infection and improved its survival rate by 54% at 96 h. In summary, this study is the first to elucidate the mechanism behind the QQ prospects of CiNN (augmented in presence of GeN) by abrogating AHL production and increasing the survival rate of C. elegans, thereby highlighting its anti-virulent properties.

Hypoxia-sensitive adjuvant loaded liposomes enhance the antimicrobial activity of azithromycin via phospholipase-triggered releasing for Pseudomonas aeruginosa biofilms eradication

Robust biofilms and the complex airway environment with thick sputum, local hypoxia and persistent inflammation induce the intractability of chronic pulmonary infections caused by Pseudomonas aeruginosa (P. aeruginosa). Herein, we proposed a type of antibiotic-adjuvant liposomes (NANO@PS-LPs), co-incorporating azithromycin (AZI), adjuvant (2-nitroimidazole derivative, 6-NIH) and biofilm dispersant (nitric oxide donor, DETA NONOate). NANO@PS-LPs possessing negatively-charged surface and good hydrophilicity could easily penetrate through the sputum layer, then disassembled triggered by overexpressed phospholipase A2 (PLA2) in the microenvironment around biofilms. Nitric oxide produced by DETA NONOate promoted P. aeruginosa biofilms dispersal. 6-NIH was reduced to 2-aminomidazole derivative (6-AIH) under a hypoxic condition, and hence acted as an AZI adjuvant to enhance the antibacterial activity of AZI. It was found that NANO@PS-LPs could significantly eliminate mature P. aeruginosa biofilms, effectively kill dispersed bacteria, inhibit the metabolism of survivors and prevent P. aeruginosa adherence to airway epithelial cells, accordingly restrain recurrent infections. Additionally, NANO@PS-LPs performed a remarkable advantage in killing AZI-resistant P. aeruginosa and removing their biofilms. In summary, NANO@PS-LPs present a potential nano-strategy to treat stubborn pseudomonal pulmonary infections and overcome correlative drug resistance.