Clinical outcomes and emergence of resistance of Pseudomonas aeruginosa infections treated with ceftolozane-tazobactam versus ceftazidime-avibactam.

Few studies compare outcomes of patients with difficult-to-treat resistance (DTR) Pseudomonas aeruginosa infections treated with ceftolozane-tazobactam versus ceftazidime-avibactam. A multicenter prospective study was conducted of unique patients with DTR P. aeruginosa infections from 2018 to 2023 receiving >72 h of ceftolozane-tazobactam or ceftazidime-avibactam, with confirmation that the P. aeruginosa isolate was susceptible to the agent administered by broth microdilution. Inverse probability weighting (IPW) incorporating propensity scores was utilized to ensure balanced baseline characteristics. Regression performed on the post-IPW group determined 30-day mortality and subsequent emergence of resistance (i.e., ≥4-fold increase in MIC) to the initial treatment (i.e., ceftolozane-tazobactam or ceftazidime-avibactam). Among 186 eligible patients, 102 (55%) received ceftolozane-tazobactam and 84 (45%) received ceftazidime-avibactam. In the post-IPW cohort, balance was achieved across all variables [e.g., demographics, severity of illness, severe immunocompromise, Charlson Comorbidity Index ≥5, continuous renal replacement therapy (CRRT), source of infection, combination therapy]. Thirty-day mortality was similar between the ceftolozane-tazobactam and ceftazidime-avibactam groups [21% vs 17%; adjusted odds ratio (aOR): 1.01 (95% confidence interval, CI: 0.90-1.14)]. Emergence of resistance was higher in the ceftolozane-tazobactam group [38% vs 25%; aOR: 1.89 (95% CI: 0.98-4.88)], but did not achieve statistical significance. Prolonged treatment durations and use of CRRT were associated with increased emergence of resistance (both P = 0.04). Although the survival of patients with DTR P. aeruginosa infections appears similar regardless of whether ceftolozane-tazobactam or ceftazidime-avibactam is prescribed, the emergence of resistance may be more concerning with the former. Plausible mechanistic explanations support these findings. Modifiable risk factors were identified that may mitigate this risk.

A Case of Relapse Pseudomonas aeruginosa Tricuspid Valve Endocarditis After AngioVac Vegectomy and Antibiotic Treatment in a Patient Using Intravenous Drugs.

Infective endocarditis (IE) is a bloodstream infection affecting the valves of the heart. IE is highly associated with morbidity and mortality if not properly managed. Pseudomonas aeruginosa (P. aeruginosa) as a cause of IE is extremely rare. This is a case of IE involving a male patient with a history of intravenous drug use (IVDU), secondary to P. aeruginosa, with associated relapse of bacteremia and native tricuspid valve endocarditis, complicated by septic pulmonary emboli, despite undergoing recent vegetation debulking using the AngioVac system (AngioDynamics, Inc., New York, USA) along with six weeks of IV antibiotics and no IVDU since then being on treatment.

The OprF porin as a potential target for the restoration of carbapenem susceptibility in Pseudomonas aeruginosa expressing acquired carbapenemases.

Carbapenem resistance in Pseudomonas aeruginosa is primarily due to the acquisition of carbapenemases and is often associated with a diminution of the membrane permeability. The outer membrane protein, OprD, is a well-known route, by which carbapenems, predominantly imipenem, can enter the cell, and its loss has been associated with reduced susceptibility to imipenem. In this study, we investigated the antibiotic susceptibility patterns of isogenic P. aeruginosa mutants containing various acquired ß-lactamases, including carbapenemases, in a porin-depleted background. We identified that the deletion of oprF was associated with some recovery of susceptibility to carbapenems.

Dual-species proteomics and targeted intervention of animal-pathogen interactions.

INTRODUCTION: Host-microbe interactions are important to human health and ecosystems globally, so elucidating the complex host-microbe interactions and associated protein expressions drives the need to develop sensitive and accurate biochemical techniques. Current proteomics techniques reveal information from the point of view of either the host or microbe, but do not provide data on the corresponding partner. Moreover, it remains challenging to simultaneously study host-microbe proteomes that reflect the direct competition between host and microbe. This raises the need to develop a dual-species proteomics method for host-microbe interactions. OBJECTIVES: We aim to establish a forward + reverse Stable Isotope Labeling with Amino acids in Cell culture (SILAC) proteomics approach to simultaneously label and quantify newly-expressed proteins of host and microbe without physical isolation, for investigating mechanisms in direct host-microbe interactions. METHODS: Using Caenorhabditis elegans-Pseudomonas aeruginosa infection model as proof-of-concept, we employed SILAC proteomics and molecular pathway analysis to characterize the differentially-expressed microbial and host proteins. We then used molecular docking and chemical characterization to identify chemical inhibitors that intercept host-microbe interactions and eliminate microbial infection. RESULTS: Based on our proteomics results, we studied the iron competition between pathogen iron scavenger and host iron uptake protein, where P. aeruginosa upregulated pyoverdine synthesis protein (PvdA) (fold-change of 5.2313) and secreted pyoverdine, and C. elegans expressed ferritin (FTN-2) (fold-change of 3.4057). Targeted intervention of iron competition was achieved using Galangin, a ginger-derived phytochemical that inhibited pyoverdine production and biofilm formation in P. aeruginosa. The Galangin-ciprofloxacin combinatorial therapy could eliminate P. aeruginosa biofilms in a fish wound infection model, and enabled animal survival. CONCLUSION: Our work provides a novel SILAC-based proteomics method that can simultaneously evaluate host and microbe proteomes, with future applications in higher host organisms and other microbial species. It also provides insights into the mechanisms dictating host-microbe interactions, offering novel strategies for anti-infective therapy.

Characterization of the Chromosomally Located Metallo-ß-Lactamase Genes blaIMP-45 and blaVIM-2 in a Carbapenem-Resistant Pseudomonas aeruginosa Clinical Isolate.

Objective: Characterization of the multidrug resistance (MDR) region in P. aeruginosa strain PA59 revealed the presence of antibiotic resistance genes, including blaIMP-45 and blaVIM-2, within a complex genetic landscape of mobile genetic elements. Methods: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) strains were isolated from Shanghai Changhai Hospital. Polymerase chain reaction (PCR) was used to detect the ß-lactamase genes in the isolated strains. Strains carrying two or more genes were subjected to whole-genome sequencing (WGS) and in-depth bioinformatics analysis. Results: A total of 94 CRPA strains were isolated, among which PA59 was determined to carry blaIMP-45 and blaVIM-2 genes. Compared with single-gene positive or other blaIMP and blaVIM dual-gene positive strains reported, PA59 exhibited a broader range of drug resistance. We discovered a multidrug resistant (MDR)-related region composed of various mobile elements in the PA59 chromosome. This region carried many resistance genes, including the target genes blaIMP-45 and blaVIM-2. By further comparing the mobile elements GI13 and Ph08, we speculated that this integron structure carrying blaIMP-45 and blaVIM-2 was initially integrated into the genomic island or prophage, forming a more complex genetic structure, and then further integrated into the PA59 chromosome through plasmids. Phylogenetic tree analysis showed limited sequence similarity between PA59 and other CRPA strains. Conclusions: This study identified PA59 as the first reported P. aeruginosa strain carrying both blaIMP-45 and blaVIM-2 on the chromosome. The assembly and annotation of the PA59 genome provide valuable insights into the genomic diversity and gene content of this clinically important pathogen, aiding the development of effective strategies against antibiotic resistance.

Tracking Antibiotic Resistance Trends in Central Iran Amidst the COVID-19 Pandemic From 2021 to 2023: A Comprehensive Epidemiological Study.

Background: The emergence of coronavirus disease in 2019 (COVID-19) appears to be having an impact on antibiotic resistance patterns. Specific circumstances during the COVID-19 era may have played a role in the spread of antimicrobial resistance (AMR). This study aimed to look at the changes in AMR patterns of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii at Al-Zahra Hospital. Materials and Methods: From March 2021 to January 2023, 3651 clinical samples were collected from patients hospitalized at Isfahan's Al-Zahra Hospital. The Clinical and Laboratory Standards Institute recommended procedures for detecting gram-negative bacteria and assessing antibiotic susceptibility were used. We divided the information into three years. Results: Highest resistance rates were seen in A. baumannii to Ciprofloxacin (98.0%) and Ampicillin-Sulbactam (97.0%). For P. aeruginosa the resistance rate for Ceftazidime (36.1), Levofloxacin (37.8), and Meropenem (47.1) dropped seriously in 2022. Conclusion: During the second year of the pandemic in central Iran, all three species studied showed rising rates of AMR. This can be attributable to two peaks within Iran on May 6, 2021 and August 27, 2021. The results of this study show that P. aeruginosa, K. pneumoniae, and A. baumannii bacteria in central Iran have a higher level of antibiotic resistance than previously studied strains before the pandemic.

The Uncommon Suspect: Pseudomonas aeruginosa and Cavitary Lung Lesions in an Immunocompetent Patient.

Cavitary lung lesions pose a formidable diagnostic challenge due to their multifaceted etiologies. While tuberculosis and other prevalent pathogens typically dominate discussions, instances of community-acquired Pseudomonas aeruginosa (P. aeruginosa) pneumonia leading to cavitation in immunocompetent individuals remain exceptionally rare. Herein, we present a compelling case of such pneumonia in a 61-year-old man with a past medical history of hypertension and coronary artery disease who presented with cough, chest pain, and subjective fever. Chest imaging revealed cavitary lung lesions, which is atypical for community-acquired pneumonia (CAP). Initial workup excluded common CAP pathogens, following which bronchoscopy with bronchoalveolar lavage (BAL) definitively diagnosed P. aeruginosa, prompting targeted antibiotic therapy. Treatment led to clinical and radiographic improvement. P. aeruginosa rarely causes CAP, especially in immunocompetent patients, and cavitary lesions further complicate diagnosis. This case highlights the importance of considering P. aeruginosa in CAP with unusual features and emphasizes the utility of bronchoscopy with BAL for diagnosis and guiding management.

Pseudomonas aeruginosa: metabolic allies and adversaries in the world of polymicrobial infections.

Pseudomonas aeruginosa (PA), an opportunistic human pathogen that is frequently linked with chronic infections in immunocompromised individuals, is also metabolically versatile, and thrives in diverse environments. Additionally, studies report that PA can interact with other microorganisms, such as bacteria, and fungi, producing unique metabolites that can modulate the host immune response, and contribute to disease pathogenesis. This review summarizes the current knowledge related to the metabolic interactions of PA with other microorganisms (Staphylococcus, Acinetobacter, Klebsiella, Enterococcus, and Candida) and human hosts, and the importance of these interactions in a polymicrobial context. Further, we highlight the potential applications of studying these metabolic interactions toward designing better diagnostic tools, and therapeutic strategies to prevent, and treat infections caused by this pathogen.

Synthesis of di-rhamnolipids by the avirulent, mono-rhamnolipid producing strain Pseudomonas aeruginosa ATCC 9027.

To construct a derivative of the avirulent Pseudomonas aeruginosa ATCC 9027 that produces high levels of di-rhamnolipid, that has better physico-chemical characteristics for biotechnological applications than mono-rhamnolipid, which is the sole type produced by ATCC 9027. We used plasmids expressing the rhlC gene, which encodes for rhamnosyl transferase II that transforms mono- to di-rhamnolipids under different promoters and in combination with the gene coding for the RhlR quorum sensing regulator, or the mono-rhamnolipid biosynthetic rhlAB operon. The plasmids tested carrying the rhlC gene under the lac promoter were plasmid prhlC and prhlRC, while prhlAB-R-C expressed this gene from the rhlA promoter, forming part of the artificially constructed rhlAB-R-C operon. We measured rhamnolipds concentrations using the orcinol method and determined the proportion of mono-rhamnolipids and di-rhamnolipids by UPLC/MS/MS. We found that the expression of rhlC in P. aeruginosa ATCC 9027 caused the production of di-rhamnolipids and that the derivative carrying plasmid prhlAB-R-C gives the best results considering total rhamnolipids and a higher proportion of di-rhamnolipids. A P. aeruginosa ATCC 9027 derivative with increased di-rhamnolipids production was developed by expressing plasmid prhlAB-R-C, that produces similar rhamnolipids levels as PAO1 type-strain and presented a higher proportion of di-rhamnolipids than this type-strain.

Minimum inhibitory and bactericidal/fungicidal concentration of commercially available products containing essential oils, zinc gluconate, or 4% chlorhexidine for Malassezia pachydermatis, Pseudomonas aeruginosa, and multi-drug resistant Staphylococcus pseudintermedius canine clinical isolates.

Skin infections are common complications in both humans and animals. Because of the increased incidence of multi-drug resistant (MDR) skin infections, essential oils have been suggested as potential alternatives to the classic antimicrobials. The goal of this study was to evaluate the minimum inhibitory and bactericidal/fungicidal concentrations (MIC and MBC/MFC) of commercially available products containing essential oils, zinc gluconate, or 4% chlorhexidine. Microbroth dilution technique was performed on clinical isolates of MDR Staphylococcus pseudintermedius (MDR-SP; n = 10), Pseudomonas aeruginosa (PA; n = 10), and Malassezia pachydermatis (MP; n = 10). For MDR-SP, essential oil-containing products showed median MICs of 1:240 and 1:320. The chlorhexidine shampoo had a MIC of 1:128,000 (0.312 µg/mL), whereas zinc gluconate products had median MICs of 1:320 and 1:160. Three essential oil-containing shampoos (MBC 1:40), the zinc gluconate (MBC 1:40), and the chlorhexidine (MBC 1:64,000 [0.625 µg/mL]) reached an MBC. For PA, essential oil-containing products showed median MICs of 1:30 and 1:80. The zinc-gluconate products had a median MIC of 1:160, whereas the chlorhexidine shampoo had a median MIC of 1:4,000 (10 µg/mL). Only the zinc-gluconate products (MBC 1:80) and the chlorhexidine shampoo (MBC 1:2,000 [20 µg/mL]) reached an MBC. For MP, essential oil-containing and zinc-gluconate products showed lower median MICs (1:4,800 and 7,200) for shampoos compared with other formulations (1:160 and 1:320), whereas the chlorhexidine shampoo had a median MIC of 1:80,000 (0.5 µg/mL). These results suggest that natural topical compounds can be an effective alternative to treat skin infections in companion animals. Further in vivo studies are needed to clinically confirm this study's results.

Molecular characterization of clinically isolated Pseudomonas aeruginosa with varying resistance to ceftazidime-avibactam and ceftolozane-tazobactam collected as a part of the ATLAS global surveillance program from 2020 to 2021.

Ceftazidime-avibactam (CZA) and ceftolozane-tazobactam (C/T) are important agents for treating multidrug-resistant P. aeruginosa infections. In this study, we evaluated the molecular characteristics of 300 globally collected clinical P. aeruginosa isolates non-susceptible (NS) to CZA, C/T, or both agents. Isolates were CZA-NS and C/T-NS (n = 57), CZA-susceptible (S) and C/T-NS (n = 145), or CZA-NS and C/T-S (n = 98) selected from the Antimicrobial Testing Leadership and Surveillance (ATLAS) surveillance program from 2020 to 2021. Characterization was by whole-genome sequencing. Analysis was performed to identify ß-lactamase genes and mutations that impact efflux regulation, AmpC regulation, and target binding (PBP3). Of the 57 CZA-NS+C/T-NS isolates, 64.9% carried a metallo-ß-lactamase (MBL), and a cumulative 84.2% carried any non-intrinsic ß-lactamase [i.e., not Pseudomonas-derived cephalosporinase (PDC) or OXA-50-like]. Of the 145 CZA-S+C/T-NS isolates, 26.2% carried an extended-spectrum ß-lactamase (ESBL) and no carbapenemase, 17.9% carried a serine-carbapenemase, and 42.1% were negative for non-intrinsic ß-lactamases. Of 98 CZA-NS+C/T-S isolates, 34.7% carried mutations previously described as causing an upregulation of the MexAB-OprM efflux pump, while only 9.2% carried a non-intrinsic ß-lactamase, and no resistance mechanism was identified in 29.6% of these isolates. MBLs were present in most isolates NS to both agents. More than half of the CZA-S+C/T-NS isolates carried serine ß-lactamases. The most frequently identified resistance mechanism identified in CZA-NS+C/T-S isolates was a marker indicating the upregulation of MexAB-OprM. No mechanism was identified that is thought to support resistance to these agents in numerous isolates. This may be due in part to the fact that whole genome sequencing (WGS) cannot directly measure gene expression of chromosomal resistance mechanisms.

Revitalizing common drugs for antibacterial, quorum quenching, and antivirulence potential against Pseudomonas aeruginosa: in vitro and in silico insights.

In the post-antibiotic era, antivirulence therapies are becoming refractory to the clinical application of existing antimicrobial regimens. Moreover, in an attempt to explore alternate intervention strategies, drug repurposing is gaining attention over development of novel drugs/antimicrobials. With the prevalence of multidrug resistance and high medical burden associated with Pseudomonas aeruginosa, there is an urgent need to devise novel therapeutics to combat this bacterial pathogen. In this context, the present study was undertaken to scrutinize the anti-quorum sensing (QS) and antivirulence potential of commonly consumed drugs such as fexofenadine (FeX), ivermectin (IvM), nitrofurantoin (NiT), levocetrizine (LvC), atorvastatin (AtS), and aceclofenac (AcF), against P. aeruginosa. The methodology involved assessment of antibacterial activity against P. aeruginosa PAO1 and quorum quenching (QQ) potential using Agrobacterium tumefaciens NTL4 biosensor strain. The antivirulence prospects were investigated by estimating the production of hallmark virulence factors in P. aeruginosa accompanied by molecular docking to predict drug associations with the QS receptors. Interestingly, all the drugs harbored antibacterial, anti-QS, and antivirulence potential in vitro, which consequently disrupted QS circuits and attenuated pseudomonal virulence phenotypically by significantly lowering the production of pyocyanin, hemolysin, pyochelin, and total bacterial protease in vitro. Moreover, the findings were validated by computational studies that predicted strong molecular interactions between the test drugs and QS receptors of P. aeruginosa. Hence, this study is the first to suggest the prospect of repurposing FeX, IvM, NiT, LvC, AtS, and AcF against P. aeruginosa.

Mucin adhesion of serial cystic fibrosis airways Pseudomonas aeruginosa isolates.

The chronic airway infections with Pseudomonas aeruginosa are the major co-morbidity in people with cystic fibrosis (CF). Within CF lungs, P. aeruginosa persists in the conducting airways together with human mucins as the most abundant structural component of its microenvironment. We investigated the adhesion of 41 serial CF airway P. aeruginosa isolates to airway mucin preparations from CF sputa. Mucins and bacteria were retrieved from five modulator-naïve patients with advanced CF lung disease. The P. aeruginosa isolates from CF airways and non-CF reference strains showed a strain-specific signature in their adhesion to ovine, porcine and bovine submaxillary mucins and CF airway mucins ranging from no or low to moderate and strong binding. Serial CF clonal isolates and colony morphotypes from the same sputum sample were as heterogeneous in their affinity to mucin as representatives of other clones thus making 'mucin binding' one of the most variable intraclonal phenotypic traits of P. aeruginosa known to date. Most P. aeruginosa CF airway isolates did not adhere more strongly to CF airway mucins than to plastic surfaces. The strong binders, however, exhibited a strain-specific affinity gradient to O-glycans, CF airway and mammalian submaxillary mucins.

Metapopulation model of phage therapy of an acute Pseudomonas aeruginosa lung infection.

Infections caused by multidrug resistant (MDR) pathogenic bacteria are a global health threat. Bacteriophages ("phage") are increasingly used as alternative or last-resort therapeutics to treat patients infected by MDR bacteria. However, the therapeutic outcomes of phage therapy may be limited by the emergence of phage resistance during treatment and/or by physical constraints that impede phage-bacteria interactions in vivo. In this work, we evaluate the role of lung spatial structure on the efficacy of phage therapy for Pseudomonas aeruginosa infections. To do so, we developed a spatially structured metapopulation network model based on the geometry of the bronchial tree, including host innate immune responses and the emergence of phage-resistant bacterial mutants. We model the ecological interactions between bacteria, phage, and the host innate immune system at the airway (node) level. The model predicts the synergistic elimination of a P. aeruginosa infection due to the combined effects of phage and neutrophils, given the sufficient innate immune activity and efficient phage-induced lysis. The metapopulation model simulations also predict that MDR bacteria are cleared faster at distal nodes of the bronchial tree. Notably, image analysis of lung tissue time series from wild-type and lymphocyte-depleted mice revealed a concordant, statistically significant pattern: infection intensity cleared in the bottom before the top of the lungs. Overall, the combined use of simulations and image analysis of in vivo experiments further supports the use of phage therapy for treating acute lung infections caused by P. aeruginosa, while highlighting potential limits to therapy in a spatially structured environment given impaired innate immune responses and/or inefficient phage-induced lysis. IMPORTANCE: Phage therapy is increasingly employed as a compassionate treatment for severe infections caused by multidrug-resistant (MDR) bacteria. However, the mixed outcomes observed in larger clinical studies highlight a gap in understanding when phage therapy succeeds or fails. Previous research from our team, using in vivo experiments and single-compartment mathematical models, demonstrated the synergistic clearance of acute P. aeruginosa pneumonia by phage and neutrophils despite the emergence of phage-resistant bacteria. In fact, the lung environment is highly structured, prompting the question of whether immunophage synergy explains the curative treatment of P. aeruginosa when incorporating realistic physical connectivity. To address this, we developed a metapopulation network model mimicking the lung branching structure to assess phage therapy efficacy for MDR P. aeruginosa pneumonia. The model predicts the synergistic elimination of P. aeruginosa by phage and neutrophils but emphasizes potential challenges in spatially structured environments, suggesting that higher innate immune levels may be required for successful bacterial clearance. Model simulations reveal a spatial pattern in pathogen clearance where P. aeruginosa are cleared faster at distal nodes of the bronchial tree than in primary nodes. Interestingly, image analysis of infected mice reveals a concordant and statistically significant pattern: infection intensity clears in the bottom before the top of the lungs. The combined use of modeling and image analysis supports the application of phage therapy for acute P. aeruginosa pneumonia while emphasizing potential challenges to curative success in spatially structured in vivo environments, including impaired innate immune responses and reduced phage efficacy.

Interspecies surfactants serve as public goods enabling surface motility in Pseudomonas aeruginosa.

In most natural environments, bacteria live in polymicrobial communities where secreted molecules from neighboring species alter bacterial behaviors, including motility, but such interactions are understudied. Pseudomonas aeruginosa is a motile opportunistic pathogen that exists in diverse multispecies environments, such as the soil, and is frequently found in human wound and respiratory tract co-infections with other bacteria, including Staphylococcus aureus. Here, we show that P. aeruginosa can co-opt secreted surfactants from other species for flagellar-based surface motility. We found that exogenous surfactants from S. aureus, other bacteria, and interkingdom species enabled P. aeruginosa to switch from swarming to an alternative surface spreading motility on semi-solid surfaces and allowed for the emergence of surface motility on hard agar where P. aeruginosa was otherwise unable to move. Although active flagellar function was required for surface spreading, known motility regulators were not essential, indicating that surface spreading may be regulated by an as yet unknown mechanism. This motility was distinct from the response of most other motile bacterial species in the presence of exogenous surfactants. Mutant analysis indicated that this P. aeruginosa motility was similar to a previously described mucin-based motility, "surfing," albeit with divergent regulation. Thus, our study demonstrates that secreted surfactants from the host as well as neighboring bacterial and interkingdom species act as public goods facilitating P. aeruginosa flagella-mediated surfing-like surface motility, thereby allowing it to access different environmental niches. IMPORTANCE: Bacterial motility is an important determinant of bacterial fitness and pathogenesis, allowing expansion and invasion to access nutrients and adapt to new environments. Here, we demonstrate that secreted surfactants from a variety of foreign species, including other bacterial species, infection hosts, fungi, and plants, facilitate surface spreading motility in the opportunistic pathogen Pseudomonas aeruginosa that is distinct from established motility phenotypes. This response to foreign surfactants also occurs in Pseudomonas putida, but not in more distantly related bacterial species. Our systematic characterization of surfactant-based surface spreading shows that these interspecies surfactants serve as public goods to enable P. aeruginosa to move and explore environmental conditions when it would be otherwise immotile.

Study on Molecular Epidemiology of Carbapenem resistant Pseudomonas aeruginosa and Related Genes of Quorum sensing Signal System.

This study aims to investigate the drug resistance, regulation mechanism of quorum sensing system, expression of related virulence genes, and epidemiological characteristics of carbapenem-resistant Pseudomonas aeruginosa (CRPA).In this study,Polymerase chain reaction amplification was performed to evaluate carbapenemase genes, oprD gene, quorum sensing system, and related virulence genes. Bacterial genotypes were analyzed using multilocus sequence typing and evolutionary analysis was conducted based on the goeBURST algorithm. The results demonstrated that a total of 47 CRPA strains were collected in this study, primarily from respiratory specimens in the ICU. Drug sensitivity results showed that the resistance rates of the 47 CRPA strains were highest for imipenem (97.87%). The loss of oprD may be the main factor contributing to carbapenem resistance in our hospital's CRPA strains.All isolates tested positive for the quorum sensing system genes lasI and rhlI/R, and the virulence gene lasB was detected in all isolates, while the algD gene was detected in 19.15% of the isolates. Among the 47 strains, 6 were untypeable, and the 41 strains with 28 different sequence types were clustered into three clonal complexes (BG1, BG2, and BG3).In conclusion, the CRPA isolates from our hospital exhibit high genetic diversity, with the deletion of the oprD gene possibly being the primary determinant of carbapenem resistance in Pseudomonas aeruginosa.Moreover, Las and RhI systems play a key role in quorum sensing signal system. Further research and development of drugs targeting quorum sensing signaling system may provide valuable guidance for the treatment of CRPA.

Strategies for Quorum Sensing inhibition as a tool for controlling Pseudomonas aeruginosa infections.

Antibiotic resistance is one of the most important concerns in global health today. Thus, a growing number of different infections are becoming harder to treat with conventional drugs and this is aggravated by the fact that fewer new antibiotics are being developed. In this context, strategies based on blocking or attenuating virulence pathways could position as very interesting therapeutic approaches since they do not focus on bacteria eradication, which should reduce the selective pressure exerted on the pathogen. This virulence depletion can be achieved by inhibiting the conserved quorum sensing (QS) system, a mechanism that enables bacteria to communicate one another in a density dependent manner. QS regulates gene expression leading to the activation of some important processes such as virulence and biofilm formation among others. Therefore, this review points out the approaches reported so far for disrupting different steps of the QS system of the multiresistant pathogen Pseudomonas aeruginosa. With this aim, the authors describe different types of molecules (enzymes, natural and synthetic small molecules, antibodies…) already identified as P. aeruginosa quorum quenchers (QQs) or QS inhibitors (QSIs) grouped according to the QS circuit that they block (Las, Rhl, Pqs and some examples from the controversial pathway Iqs). The importance of the discovery of new QSIs and QQs is expected to help on reducing antibiotic doses or at least to act as adjuvants to increase antibiotic treatment effect. Moreover, this article also highlights the advantages and possible drawbacks of each strategy and it also summarizes future perspectives in the field.

Glycomimetics as Candidates for Treatment and Prevention of Catheter-associated Biofilms Formed by Pseudomonas aeruginosa.

Bacteria develop biofilms for protection and persistent colonization. Biofilms of pathogenic bacteria can lead to serious medical problems. Bacterial biofilms on catheters used in the treatment of urinary tract diseases represent a major challenge for antibiotic therapy. Several attempts to eradicate biofilms using classical antibiotics and various alternatives, including antibiotic treatment of surfaces, surfaces that release silver ions, and surfaces with anti-adhesive properties, have not shown clinical efficacy in biofilm prevention or removal. Pseudomonas aeruginosa is one of the most problematic biofilm-forming uropathogens and accounts for approximately 10% of urinary tract infections. Novel glycomimetics that inhibit bacterial lectins have shown promising results in the prevention of P. aeruginosa biofilms and in interference with bacterial virulence. This mini-review summarizes the status of glycomimetic development and provides a perspective on their use in clinical practice. PATIENT SUMMARY: For patients with recurrent urinary tract infections and patients needing long-term catheter use to manage urinary problems, biofilms formed by bacteria can be a problem and are difficult to treat. New compounds that mimic carbohydrates, called glycomimetics, have shown promise in inhibiting these bacteria and the biofilms they form. More research on these compounds is needed before they can be used to treat patients.

Flagellum-deficient Pseudomonas aeruginosa is more virulent than non-motile but flagellated mutants in a cystic fibrosis mouse model.

Loss of the flagellum marks the pathoadaptation of Pseudomonas aeruginosa to the cystic fibrosis (CF) airway environment during lung disease. Losing the flagellum is advantageous to the bacterium as the flagellum can be recognized by immune cells. The primary purpose of the flagellum is, however, to provide motility to the bacterium. Our goal was to determine whether the loss of flagellar motility or the loss of flagellum expression contributes to P. aeruginosa lung infection in CF. To address this, wild-type and gut-corrected FABP-human cystic fibrosis transmembrane conductance regulator (hCFTR) mice deficient in the murine Cftr gene were infected intratracheally with lethal doses of wild-type or flagellum-deficient P. aeruginosa. While there was no significant difference in the survival of wild-type mice after infection with either of the bacterial strains, a significantly higher mortality was observed in FABP-hCFTR mice infected with flagellum-deficient P. aeruginosa, compared to mice infected with their flagellated counterparts. When FABP-hCFTR mice were infected with isogenic, motility-deficient flagellated mutants, animal survival and lung bacterial titers were similar to those observed in mice infected with the wild-type bacterium. Airway levels of neutrophils and the amount neutrophil elastase were similar in mice infected with either the wild-type bacteria or the flagellum-deficient P. aeruginosa. Our results show that FABP-hCFTR mice have a different response to flagellum loss in P. aeruginosa compared to wild-type animals. The loss of flagellum expression, rather than the loss of motility, is the main driver behind the increased virulence of flagellum-deficient P. aeruginosa in CF. These observations provide new insight into P. aeruginosa virulence in CF.IMPORTANCEPseudomonas aeruginosa, a major respiratory pathogen in cystic fibrosis, is known to lose its flagellum during the course of infection in the airways. Here, we show that the loss of flagellum leads to a more enhanced virulence in Cftr-deficient cystic fibrosis mice than in control animals. Loss of flagellum expression, rather than the loss of flagellar swimming motility, represents the main driver behind this increased virulence suggesting that this appendage plays a specific role in P. aeruginosa virulence in cystic fibrosis airways.