How does Pseudomonas aeruginosa affect the progression of bronchiectasis?

Increasing serum miR-223-3p indicates the onset, severe development, and adverse prognosis of bronchiectasis: a retrospective study

BACKGROUND

miR-223-3p has been demonstrated as a Pseudomonas aeruginosa colonization-related miRNA in bronchiectasis (BE), but its clinical value in BE has not been revealed, which is of great significance for the clinical diagnosis and monitoring of BE. This study aimed to identify a reliable biomarker for screening BE and predicting patients' outcomes.

METHODS

The serum expression of miR-223-3p was compared between healthy individuals (n = 101) and BE patients (n = 133) and evaluated its potential in distinguishing BE patients. The severity of BE patients was estimated by BSI and FACED score, and the correlation of miR-223-3p with inflammation and severity of BE patients was evaluated by Pearson correlation analysis. BE patients were followed up for 3 years, and the predictive value of miR-223-3p in prognosis was assessed by logistic regression analysis.

RESULTS

Significant upregulation of miR-223-3p was observed in BE patients, which significantly distinguished BE patients and showed positive correlations with C-reactive protein (CRP), procalcitonin (PCT), interleukin 6 (IL-6), and neutrophil-to-lymphocyte ratio (NLR) of BE patients. Additionally, miR-223-3p was also positively correlated with BSI and FACED scores, indicating its correlation with inflammation and severity of BE. BE patients with adverse prognoses showed a higher serum miR-223-3p level, which was identified as an adverse prognostic factor and discriminated patients with different prognoses.

CONCLUSION

Increasing serum miR-223-3p can be considered a biomarker for the onset, severity, and prognosis of BE.

Establishment of portable Pseudomonas aeruginosa detection platform based on one-tube CRISPR/Cas12a combined with recombinase polymerase amplification technology

Pseudomonas aeruginosa, a common Gram-negative bacterium, is associated with diverse diseases. Its increasing resistance to antibiotics presents challenges in clinical treatment. The predominant diagnostic approach involves conventional biochemical cultures, known for their time and labor intensiveness. Despite progress in isothermal amplification studies, limitations persist, including reliance on specialized equipment, intricate primer design, and aerosol contamination. Therefore, there is a demand for enhanced clinical assays. This study successfully combined RPA and CRISPR/Cas12a techniques. Through a series of experiments involving the design and screening of lasB crRNA, the creation of lasB RPA primers, and the establishment of a streamlined RPA-CRISPR/Cas12a assay, the study developed a one-tube detection method targeting P. aeruginosa's lasB gene. The assay demonstrated inclusive behavior across standard and 21 isolates, while specifically discerning P. aeruginosa from diverse strains. Sensitivity reached 15.9 CFU/reaction. Clinical validation revealed a 97.62% concordance with traditional methods. The one-tube assay's protocol mitigated aerosol contamination. Offering precision, specificity, and sensitivity, this method shows promise for field applications in resource-scarce regions, enabling early detection and improved management of P. aeruginosa infections.

A phase 4 multicentre, 2×2 factorial randomised, double-blind, placebo-controlled trial to investigate the efficacy and safety of tobramycin inhalation solution for Pseudomonas aeruginosa eradication in bronchiectasis: ERASE

Chronic Pseudomonas aeruginosa (PA) infection significantly contributes to morbidity and mortality in bronchiectasis patients. Initiating antibiotics early may lead to the eradication of PA. Here we outline the design of a trial (ERASE; NCT06093191) assessing the efficacy and safety of inhaled tobramycin, alone or with oral ciprofloxacin, in bronchiectasis patients with a new isolation of PA. This multicentre, 2×2 factorial randomised, double-blind, placebo-controlled, parallel-group trial includes a 2-week screening period, a 12-week treatment phase (with a combination of ciprofloxacin or a placebo at initial 2 weeks) and a 24-week follow-up. 364 adults with bronchiectasis and a new PA isolation will be randomly assigned to one of four groups: placebo (inhaled saline and ciprofloxacin placebo twice daily), ciprofloxacin alone (750 mg ciprofloxacin and inhaled saline twice daily), inhaled tobramycin alone (inhaled 300 mg tobramycin and ciprofloxacin placebo twice daily) or a combination of both drugs (inhaled 300 mg tobramycin and 750 mg ciprofloxacin twice daily). The primary objective of this study is to assess the proportion of patients successfully eradicating PA in each group by the end of the study. Efficacy will be evaluated based on the eradication rate of PA at other time points (12, 24 and 36 weeks), the occurrence of exacerbations and hospitalisations, time to first pulmonary exacerbations, patient-reported outcomes, symptom measures, pulmonary function tests and the cost of hospitalisations. To date no randomised trial has evaluated the benefit of different PA eradication strategies in bronchiectasis patients. The ERASE trial will therefore generate crucial data to inform future clinical guidelines.

Pseudomonas aeruginosa-induced mitochondrial dysfunction inhibits proinflammatory cytokine secretion and enhances cytotoxicity in mouse macrophages in a reactive oxygen species (ROS)-dependent way

随着铜绿假单胞菌（铜绿）的耐药性逐年增强，铜绿感染已经成为公共医疗卫生的重点关注问题。线粒体自噬及其介导的线粒体功能障碍在多种细菌感染中已被报道，但线粒体功能障碍在宿主调控铜绿感染中的作用尚不明确。因此，本研究建立铜绿刺激小鼠巨噬细胞感染模型和小鼠急性铜绿感染模型，探讨铜绿是否通过诱导线粒体自噬改变线粒体功能，进而影响宿主免疫炎症反应和细胞毒性，并通过监测生存率和肺组织病理学变化进一步确定线粒体自噬在小鼠铜绿体内感染模型中的作用。结果表明，铜绿引起小鼠腹腔巨噬细胞线粒体功能障碍，并通过线粒体自噬途径清除铜绿刺激引起的活性氧（ROS）累积，从而抑制铜绿引起的促炎性细胞因子分泌并增强细胞毒性。体内实验进一步确认线粒体自噬在铜绿体内感染中的作用。

Pseudomonas aeruginosa isolation is an important predictor for recurrent hemoptysis after bronchial artery embolization in patients with idiopathic bronchiectasis: a multicenter cohort study

BACKGROUND

Nearly half of bronchiectasis patients receiving bronchial artery embolization (BAE) still have recurrent hemoptysis, which may be life-threatening. Worse still, the underlying risk factors of recurrence remain unknown.

METHODS

A retrospective cohort was conducted of patients with idiopathic bronchiectasis who received BAE from 2015 to 2019 at eight centers. Patients were followed up for at least 24 months post BAE. Based on the outcomes of recurrent hemoptysis and recurrent severe hemoptysis, a Cox regression model was used to identify risk factors for recurrence.

RESULTS

A total of 588 individuals were included. The median follow-up period was 34.0 months (interquartile range: 24.3-53.3 months). The 1-month, 1-year, 2-year, and 5-year cumulative recurrent hemoptysis-free rates were 87.2%, 67.5%, 57.6%, and 49.4%, respectively. The following factors were relative to recurrent hemoptysis: 24-h sputum volume (hazard ratio [HR] = 1.99 [95% confidence interval [95% CI]: 1.25-3.15, p = 0.015]), isolation of Pseudomonas aeruginosa (HR = 1.50 [95% CI: 1.13-2.00, p = 0.003]), extensive bronchiectasis (HR = 2.00 [95% CI: 1.29-3.09, p = 0.002]), and aberrant bronchial arteries (AbBAs) (HR = 1.45 [95% CI: 1.09-1.93, p = 0.014]). The area under the receiver operating characteristic curve of the nomogram was 0.728 [95% CI: 0.688-0.769].

CONCLUSIONS

Isolation of Pseudomonas aeruginosa is an important independent predictor of recurrent hemoptysis. The clearance of Pseudomonas aeruginosa might effectively reduce the hemoptysis recurrence rate.

Necroptosis signaling and NLRP3 inflammasome cross-talking in epithelium facilitate Pseudomonas aeruginosa mediated lung injury

Pseudomonas aeruginosa induced acute lung injury is such a serious risk to public health, but the pathological regulation remains unclear. Here, we reported that PA mediated epithelial necroptosis plays an important role in pathological process. Pharmacological and genomic ablation of necroptosis signaling ameliorate PA mediated ALI and pulmonary inflammation. Our results further proved NLRP3 inflammasome to involve in the process. Mechanism investigation revealed the cross-talking between inflammasome activation and necroptosis that MLKL-dependent necroptosis signaling promotes the change of mitochondrial membrane potential for the release of reactive oxygen species (ROS), which is the important trigger for functional inflammasome activation. Furthermore, antioxidants such as Mito-TEMPO was confirmed to significantly restrain inflammasome activation in epithelium, resulting in a reduction in PA induced pulmonary inflammation. Taken together, our findings revealed that necroptosis-triggered NLRP3 inflammasome in epithelium plays a crucial role in PA mediated injury, which could be a potential therapeutic target for pulmonary inflammation.

Decreased Sphingosine Due to Down-Regulation of Acid Ceramidase Expression in Airway of Bronchiectasis Patients: A Potential Contributor to Pseudomonas aeruginosa Infection

Purpose

To assess the metabolites associated with Pseudomonas aeruginosa infection by analyzing the microbial diversity and metabolomics in lower respiratory tract of bronchiectasis patients and to explore the therapeutic approaches for Pseudomonas aeruginosa infection.

Methods

Bronchoalveolar lavage fluid samples from bronchiectasis patients and controls were analyzed by 16S rRNA and ITS sequencing, and metabolomic analysis was performed by liquid chromatography/mass spectrometry. A co-culture model of air-liquid interface cultured human bronchial epithelial cell with Pseudomonas aeruginosa was constructed to verify the correlation between sphingosine metabolism, acid ceramidase expression, and Pseudomonas aeruginosa infection.

Results

After screening, 54 bronchiectasis patients and 12 healthy controls were included. Sphingosine levels in bronchoalveolar lavage fluid were positively correlated with lower respiratory tract microbial diversity and negatively correlated with the abundance of Pseudomonas spp. Moreover, sphingosine levels in bronchoalveolar lavage fluid and acid ceramidase expression levels in lung tissue specimens were significantly lower in bronchiectasis patients than in healthy controls. Sphingosine levels and acid ceramidase expression levels were also significantly lower in bronchiectasis patients with positive Pseudomonas aeruginosa cultures than in bronchiectasis patients without Pseudomonas aeruginosa infection. Acid ceramidase expression in air-liquid interface cultured human bronchial epithelial cell had significantly increased after 6 h of Pseudomonas aeruginosa infection, while it had decreased significantly after 24 h of infection. In vitro experiments showed that sphingosine had a bactericidal effect on Pseudomonas aeruginosa by directly disrupting its cell wall and cell membrane. Furthermore, adherence of Pseudomonas aeruginosa on bronchial epithelial cells was significantly reduced after sphingosine supplementation.

Conclusion

Down-regulation of acid ceramidase expression in airway epithelial cells of bronchiectasis patients leads to insufficient metabolism of sphingosine, which has a bactericidal effect, and consequently weakens the clearance of Pseudomonas aeruginosa; thus, a vicious circle is formed. Exogenous supplementation with sphingosine aids bronchial epithelial cells in resisting Pseudomonas aeruginosa infection.

What Is New in the Anti–Pseudomonas aeruginosa Clinical Development Pipeline Since the 2017 WHO Alert?

The spread of antibiotic-resistant bacteria poses a substantial threat to morbidity and mortality worldwide. Carbapenem-resistant Pseudomonas aeruginosa (CRPA) are considered “critical-priority” bacteria by the World Health Organization (WHO) since 2017 taking into account criteria such as patient mortality, global burden disease, and worldwide trend of multi-drug resistance (MDR). Indeed P. aeruginosa can be particularly difficult to eliminate from patients due to its combinatory antibiotic resistance, multifactorial virulence, and ability to over-adapt in a dynamic way. Research is active, but the course to a validated efficacy of a new treatment is still long and uncertain. What is new in the anti–P. aeruginosa clinical development pipeline since the 2017 WHO alert? This review focuses on new solutions for P. aeruginosa infections that are in active clinical development, i.e., currently being tested in humans and may be approved for patients in the coming years. Among 18 drugs of interest in December 2021 anti–P. aeruginosa development pipeline described here, only one new combination of β-lactam/β-lactamase inhibitor is in phase III trial. Derivatives of existing antibiotics considered as “traditional agents” are over-represented. Diverse “non-traditional agents” including bacteriophages, iron mimetic/chelator, and anti-virulence factors are significantly represented but unfortunately still in early clinical stages. Despite decade of efforts, there is no vaccine currently in clinical development to prevent P. aeruginosa infections. Studying pipeline anti–P. aeruginosa since 2017 up to now shows how to provide a new treatment for patients can be a difficult task. Given the process duration, the clinical pipeline remains unsatisfactory leading best case to the approval of new antibacterial drugs that treat CRPA in several years. Beyond investment needed to build a robust pipeline, the Community needs to reinvent medicine with new strategies of development to avoid the disaster. Among “non-traditional agents”, anti-virulence strategy may have the potential through novel and non-killing modes of action to reduce the selective pressure responsible of MDR.

Antioxidant and Anti-Inflammatory Effects of Thyme (Thymus vulgaris L.) Essential Oils Prepared at Different Plant Phenophases on Pseudomonas aeruginosa LPS-Activated THP-1 Macrophages

Thyme (Thymus vulgaris L.) essential oil (TEO) is widely used as an alternative therapy especially for infections of the upper respiratory tract. TEO possesses antiviral, antibacterial, and antifungal properties. The emerging antibiotic resistance of bacterial strains, including Pseudomonas aeruginosa, has prompted the urge to find alternative treatments. In the present study, we examined the anti-inflammatory and antioxidant effects of thymol, the main compound of TEO, and two TEOs prepared at the beginning and at the end of the flowering period that may make these oils promising candidates as complementary or alternative therapies against P. aeruginosa infections. The activity measurements of the antioxidant enzymes peroxidase (PX), catalase (CAT), and superoxide dismutase (SOD) as well as the determination of total antioxidant capacity of P. aeruginosa-activated THP-1 cells revealed that thymol and both TEOs increased CAT and SOD activity as well as the antioxidant capacity of the THP-1 cells. The measurements of the proinflammatory cytokine mRNA expression and secreted protein level of LPS-activated THP-1 cells showed that from the two TEOs, only TEO prepared at the beginning of the flowering period acted as a potent inhibitor of the synthesis of IL-6, IL-8, IL-β, and TNF-α. Our results suggest that not only thymol, but also the synergism or the antagonistic effects of the additional compounds of the essential oils are responsible for the anti-inflammatory activity of TEOs.

Synergistic Activity of Imipenem in Combination with Ceftazidime/Avibactam or Avibactam against Non-MBL-Producing Extensively Drug-Resistant Pseudomonas aeruginosa

Extensively drug-resistant Pseudomonas aeruginosa (XDRPA) infection is a significant public health threat due to a lack of effective therapeutic options. New β-lactam-β-lactamase inhibitor combinations, including ceftazidime-avibactam (CZA), have shown a high resistance rate to XDRPA. This study was therefore conducted to describe the underlying genomic mechanism of resistance for CZA nonsusceptible XDRPA strains that are non-metallo-β-lactamase (MBL) producers as well as to examine synergism of CZA and other antipseudomonal agents. Furthermore, the synergistic antibacterial activity of the most effective antimicrobial combination against non-MBL-producing XDRPA was evaluated through in vitro experiments. The resistance profiles of 15 CZA-resistant XDRPA strains isolated from clinical specimens in China-Japan Friendship Hospital between January 2017 to December 2020 were obtained by whole-genome sequencing (WGS) analysis. MBL genes bla_IMP-1 and bla_IMP-45 were found in 2 isolates (2/15, 13.3%); the other underlying CZA-resistance mechanisms involved the decreased OprD porin (13/13), bla_AmpC overexpression (8/13) or mutation (13/13), and upregulated efflux pumps (13/13). CZA-imipenem (CZA-IPM) combination was identified to be the most effective against non-MBL-producing XDRPA according to the results of WGS analysis and combined antimicrobial susceptibility tests, with an approximately 16.62-fold reduction in MICs compared to CZA alone. Furthermore, the results of checkerboard analysis and growth curve displayed the synergistic antimicrobial activity of CZA and IPM against non-MBL-producing XDRPA. Electron microscopy also revealed that CZA-IPM combination might lead to more cellular structural alterations than CZA or IPM alone. This study suggested that the CZA-IPM combination has potential for non-MBL-producing XDRPA with bla_AmpC overexpression or mutation, decreased OprD porin, and upregulated efflux pumps. IMPORTANCE Handling the infections by extensively drug-resistant Pseudomonas aeruginosa (XDRPA) strains is challenging due to their complicated antibiotic resistance mechanisms in immunosuppressed patients with pulmonary diseases (e.g., cystic fibrosis, chronic obstructive pulmonary disease, and lung transplant), ventilator-associated pneumonia, and bloodstream infections. The current study suggested the potentiality of the ceftazidime-avibactam-imipenem combination against XDRPA with bla_AmpC overexpression or mutation, decreased OprD porin, and/or upregulated efflux pumps. Our findings indicate the necessity of combined drug sensitivity tests against XDRPA and also lay a foundation for the development of prevention, control, and treatment strategies in XDRPA infections.

Neutrophil side fluorescence: a new indicator for predicting the severity of patients with bronchiectasis

Background

Neutrophilic inflammation in the airway is a hallmark of bronchiectasis. Neutrophil extracellular traps (NETs) have been reported to play an important role in the occurrence and development of bronchiectasis. Neutrophil side fluorescence is one of the characteristics of neutrophils that can reflect the activation of neutrophils and the formation of NETs.

Objective

To explore the relationship between the values of neutrophil side fluorescence (NEUT-SFL) in the peripheral blood of bronchiectasis patients, and the severity of the disease.

Methods

82 patients with bronchiectasis from the Department of Respiratory and Critical Medicine, at the Third Affiliated Hospital of Southern Medical University and were scored with Bronchiectasis Severity Index (BSI) (2019–2021). The clinical data such as the value of NEUT-SFL, neutrophil count, C-reactive protein, and procalcitonin levels were collected and retrospectively analyzed. NEUT-SFL values neutrophil count from 28 healthy subjects were also used to ascertain cut-off values.

Results

Based on the BSI scores, patients were divided into three categories as mild (32%), moderate (29%), and severe (39%). Our results showed that the values of NEUT-SFL were higher in bronchiectasis patients compared to healthy controls. The levels of NEUT-SFL positively correlated with the high BSI scores in patients (P = 0.037, r = 0.23) and negatively correlated with the lung function in these patients (r = − 0.35, P = 0.001). The area under the ROC curve was 0.813, the best cut-off was 42.145, indicating that NEUT-SFL values > 42.145 can potentially predict the severity of bronchiectasis.

Conclusions

The values of NEUT-SFL in the peripheral blood can be used for predicting the severity of bronchiectasis.

Influence of Comorbidities and Airway Clearance on Mortality and Outcomes of Patients With Severe Bronchiectasis Exacerbations in Taiwan

Bronchiectasis is characterized by systemic inflammation and multiple comorbidities. This study aimed to investigate the clinical outcomes based on the bronchiectasis etiology comorbidity index (BACI) score in patients hospitalized for severe bronchiectasis exacerbations. We included non-cystic fibrosis patients hospitalized for severe bronchiectasis exacerbations between January 2008 and December 2016 from the Chang Gung Research Database (CGRD) cohort. The main outcome was the 1-year mortality rate after severe exacerbations. We used the Cox regression model to assess the risk factors of 1-year mortality. Of 1,235 patients who were hospitalized for severe bronchiectasis exacerbations, 641 were in the BACI < 6 group and 594 in the BACI ≥ 6 group. The BACI ≥ 6 group had more previous exacerbations and a lower FEV₁. Pseudomonas aeruginosa (19.1%) was the most common bacterium, followed by Klebsiella pneumoniae (7.5%). Overall, 11.8% of patients had respiratory failure and the hospital mortality was 3.0%. After discharge, compared to the BACI < 6 group, the BACI ≥ 6 group had a significantly higher cumulative incidence of respiratory failure and mortality in a 1-year follow-up. The risk factors for 1-year mortality in a multivariate analysis include age [hazard ratio (HR) 4.38, p = 0.01], being male (HR 4.38, p = 0.01), and systemic corticosteroid usage (HR 6.35, p = 0.001), while airway clearance therapy (ACT) (HR 0.50, p = 0.010) was associated with a lower mortality risk. An increased risk of respiratory failure and mortality in a 1-year follow-up after severe exacerbations was observed in bronchiectasis patients with multimorbidities, particularly older age patients, male patients, and patients with a history of systemic corticosteroid use. ACT could effectively improve the risk for 1-year mortality.

Inhaled antibiotics for treatment of adults with non-cystic fibrosis bronchiectasis: A systematic review and meta-analysis

BACKGROUND

Inhaled antibiotics (IA) in non-cystic fibrosis bronchiectasis (NCFB) are recommended by some clinical practice guidelines for prevention or treatment of NCFB exacerbations.

METHODS

We performed a systematic review and meta-analysis to evaluate the efficacy and safety of IA use for treatment of adults with NCFB and Pseudomonas aeruginosa chronic bronchial infection. The search was performed in the Cochrane Library, PubMed, and Web of Science databases from 2000 to 2019. Studies of IA for treatment of stable or exacerbated NCFB adults (≥18 years) with P. aeruginosa infection were considered eligible. PROSPERO Registration number: CRD42019136154.

RESULTS

Twelve trials (2476 participants) were included. IA therapy increased P. aeruginosa eradication from sputum in patients with exacerbations (OR: 3.19, 95%CI: 1.70-5.99) with similar effects on stable patients (OR: 7.22, 95%CI: 2.81-18.59), and a trend to reduced emergence of new respiratory pathogens (OR: 0.58, 95%CI: 0.28-1.18). IA achieved significant reduced exacerbation rates (RR: 0.90; 95%CI: 0.82-0.98) in stable patients, with a number needed to treat (NNT) of 59, but no significant changes in FEV₁, mortality, hospitalizations or quality of life were identified. In stable patients, IA use increased antimicrobial resistance (RR: 2.10, 95%CI: 1.35-3.27) at the end of therapy, with a number needed to treat of 6.

CONCLUSIONS

IA therapy achieved a statistically significant eradication of P. aeruginosa from sputum, with a 10% reduction of exacerbations in stable patients. This effect has to be balanced with significant increases in antimicrobial resistance. Our meta-analysis failed to show a significant benefit in terms of patient-centered outcomes.

Bronchiolitis Obliterans and Primary Ciliary Dyskinesia: What Is the Link?

Bronchiolitis obliterans (BO) is a rare form of chronic obstructive lung disease characterized by obliteration of the small airways caused by inflammation and fibrosis. In children, BO most commonly appears following a severe lower respiratory tract infection. This phenomenon has been described as post-infectious BO (PIBO). PIBO presents with dyspnea, tachypnea, and persistent hypoxemia, as well as characteristic radiographic findings on high-resolution CT (HRCT) of the lungs. A few DNAH1 genetic variants have been postulated to have a role in the development of BO in patients with primary ciliary dyskinesia (PCD), but there is limited evidence regarding this, and etiologies are uncertain. PCD is a genetically heterogeneous autosomal recessive disorder characterized by ciliary dysfunction that causes impaired mucociliary clearance, leading to bronchiectasis and recurrent lower respiratory tract infections due to several pathogenic organisms including Pseudomonas aeruginosa. The link between rare PCD genetic variants and BO remains undetermined. We report the first case in Puerto Rico with Pseudomonal PIBO as the initial presentation of PCD; the patient was a four-year-old male. We also engage in a comparison of our case with previously reported cases of PIBO in PCD patients.

Facile antibacterial materials with turbine-like structure for P. aeruginosa infected scald wound healing

Pseudomonas aeruginosa (P. aeruginosa) is a popular hospital pathogen and the major cause of morbidity and mortality in patients with cystic fibrosis (CF) and impaired immune system. Herein, we designed and synthesized a series of organic molecules MTEBT-n (n = 1, 2, 3) to specifically and effectively kill P. aeruginosa. Hydrophobic triphenylamine was selected as the skeleton, and hydrophilic primary ammonium salts that can easily penetrate the cell walls of Gram-negative bacteria and accumulate in the bacteria were used to adjust the hydrophilic-hydrophobic ratio of the molecules, resulting in different antibacterial activity. As the hydrophilic-hydrophobic ratio increased in the structures from MTEBT-1 to MTEBT-3, the antibacterial activity of the three molecules were gradually enhanced with killing effects of 25%, 75% and 95% against P. aeruginosa, respectively. The antibacterial mechanisms of MTEBT-n were demonstrated to destroy the bacterial membrane, which could effectively prevent the development of drug resistance. In addition, MTEBT-3 with the highest antibacterial activity could inhibit P. aeruginosa biofilm very well, and heal the P. aeruginosa infected scald wounds. This work provides a potential organic antimicrobial material for clinical antimicrobial therapy of P. aeruginosa infection, and offers a molecular engineering strategy for designing new antimicrobials.

[Current microbiological aspects of community respiratory infection beyond COVID-19]

From a microbiological point of view, both empirical and targeted antimicrobial treatment in respiratory infection is based on the sensitivity profile of isolated microorganisms and the possible resistance mechanisms that they may present. The latter may vary in different geographic areas according to prescription profiles and vaccination programs. Beta-lactam antibiotics, fluoroquinolones, and macrolides are the most commonly used antimicrobials during the exacerbations of chronic obstructive pulmonary disease and community-acquired pneumonia. In their prescription, different aspects such as intrinsic activity, bactericidal effect or their ability to prevent the development of resistance must be taken into account. The latter is related to the PK/PD parameters, the mutant prevention concentration and the so-called selection window. More recently, the potential ecological impact has grown in importance, not only on the intestinal microbiota, but also on the respiratory one. Maintaining the state of eubiosis requires the use of antimicrobials with a low profile of action on anaerobic bacteria. With their use, the resilience of the bacterial populations belonging to the microbiota, the state of resistance of colonization and the collateral damage related to the emergence of resistance to the antimicrobials in pathogens causing the infections and in the bacterial populations integrating the microbiota.

Bacterial Interactions with Aspergillus fumigatus in the Immunocompromised Lung

The immunocompromised airways are susceptible to infections caused by a range of pathogens which increases the opportunity for polymicrobial interactions to occur. Pseudomonas aeruginosa and Staphylococcus aureus are the predominant causes of pulmonary infection for individuals with respiratory disorders such as cystic fibrosis (CF). The spore-forming fungus Aspergillus fumigatus, is most frequently isolated with P. aeruginosa, and co-infection results in poor outcomes for patients. It is therefore clinically important to understand how these pathogens interact with each other and how such interactions may contribute to disease progression so that appropriate therapeutic strategies may be developed. Despite its persistence in the airways throughout the life of a patient, A. fumigatus rarely becomes the dominant pathogen. In vitro interaction studies have revealed remarkable insights into the molecular mechanisms that drive agonistic and antagonistic interactions that occur between A. fumigatus and pulmonary bacterial pathogens such as P. aeruginosa. Crucially, these studies demonstrate that although bacteria may predominate in a competitive environment, A. fumigatus has the capacity to persist and contribute to disease.

It's Not Easy Being Green: A Narrative Review on the Microbiology, Virulence and Therapeutic Prospects of Multidrug-Resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is the most frequent cause of infection among non-fermenting Gram-negative bacteria, predominantly affecting immunocompromised patients, but its pathogenic role should not be disregarded in immunocompetent patients. These pathogens present a concerning therapeutic challenge to clinicians, both in community and in hospital settings, due to their increasing prevalence of resistance, and this may lead to prolonged therapy, sequelae, and excess mortality in the affected patient population. The resistance mechanisms of P. aeruginosa may be classified into intrinsic and acquired resistance mechanisms. These mechanisms lead to occurrence of resistant strains against important antibiotics-relevant in the treatment of P. aeruginosa infections-such as β-lactams, quinolones, aminoglycosides, and colistin. The occurrence of a specific resistotype of P. aeruginosa, namely the emergence of carbapenem-resistant but cephalosporin-susceptible (Car-R/Ceph-S) strains, has received substantial attention from clinical microbiologists and infection control specialists; nevertheless, the available literature on this topic is still scarce. The aim of this present review paper is to provide a concise summary on the adaptability, virulence, and antibiotic resistance of P. aeruginosa to a readership of basic scientists and clinicians.

Impact of Pseudomonas aeruginosa Infection on Patients with Chronic Inflammatory Airway Diseases

Pseudomonas aeruginosa (P. aeruginosa) is a ubiquitous and opportunistic microorganism and is considered one of the most significant pathogens that produce chronic colonization and infection of the lower respiratory tract, especially in people with chronic inflammatory airway diseases such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), and bronchiectasis. From a microbiological viewpoint, the presence and persistence of P. aeruginosa over time are characterized by adaptation within the host that precludes any rapid, devastating injury to the host. Moreover, this microorganism usually develops antibiotic resistance, which is accelerated in chronic infections especially in those situations where the frequent use of antimicrobials facilitates the selection of “hypermutator P. aeruginosa strain”. This phenomenon has been observed in people with bronchiectasis, CF, and the “exacerbator” COPD phenotype. From a clinical point of view, a chronic bronchial infection of P. aeruginosa has been related to more severity and poor prognosis in people with CF, bronchiectasis, and probably in COPD, but little is known on the effect of this microorganism infection in people with asthma. The relationship between the impact and treatment of P. aeruginosa infection in people with airway diseases emerges as an important future challenge and it is the most important objective of this review.