Unveiling the Launaea nudicaulis (L.) Hook medicinal bioactivities: phytochemical analysis, antibacterial, antibiofilm, and anticancer activities.

Commonly used antimicrobial agents are no longer effective due to their overuse or misuse. In addition, many medicinal plant extracts can combat infectious diseases due to their main active constituents or secondary metabolites. The current study aimed to assess the bioactivities of Launaea nudicaulis (LN) leaf extract (LE) against different multi-drug resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa) isolates. The ethyl acetate extract of a Launaea nudicaulis (LN) leaf was analyzed using GC-MS, which identified 27 key bioactive compounds. The major constituents found were as follows: 7-acetyl-6-ethyl-1,1,4,4-tetramethyltetralin, isopropyl myristate, thiocarbamic acid, N,N-dimethyl, S-1,3-diphenyl-2-butenyl ester, hahnfett, cyclopentane acetic acid, 3-oxo-2-pentyl-, methyl ester, hexadecanoic acid, and dotriacontane. Our study demonstrated that the LN leaf was a rich source of other important phytochemicals, including phenolic acids, tannins, saponins, and steroids. The relative biosafety of the L. nudicaulis LE was determined from the elevated inhibitory concentration 50 (IC50) of 262 µg/mL, as calculated from the cytotoxicity assay against the Wi-38 normal cell line. Conversely, 12.7 and 24.5 µg/mL were the recorded low IC50 values for the tested extract against the MCF-7 and Hep-G2 cancerous cell lines, respectively, reflecting its potent activity against the tested cancerous cell lines. Microbiologically, the susceptible P. aeruginosa isolates to the tested extract showed a growth inhibition zone diameter, in the well diffusion assay, ranging from 11.34 ± 0.47 to 26.67 ± 0.47 mm, and a percent inhibition (PI) value of 50-106.2%, reflecting its acceptable activity. In addition, the broth microdilution assay recorded minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in the ranges of 15.625-1,000 µg/mL and 125-1,000 µg/mL, respectively. In conclusion, the L. nudicaulis LE revealed showed promising activity and high selectivity against P. aeruginosa. Moreover, the extract exhibited natural anticancer activities with safe low concentrations, indicating its potential as a superior candidate for future studies of its active constituents.

Highly Effective Biocides against Pseudomonas aeruginosa Reveal New Mechanistic Insights Across Gram-Negative Bacteria.

Pseudomonas aeruginosa is a major nosocomial pathogen that persists in healthcare settings despite rigorous disinfection protocols due to intrinsic mechanisms conferring resistance. We sought to systematically assess cationic biocide efficacy against this pathogen using a panel of multidrug-resistant P. aeruginosa clinical isolates. Our studies revealed widespread resistance to commercial cationic disinfectants that are the current standard of care, raising concerns about their efficacy. To address this shortcoming, we highlight a new class of quaternary phosphonium compounds that are highly effective against all members of the panel. To understand the difference in efficacy, mechanism of action studies were carried out, which identified a discrete inner-membrane selective target. Resistance selection studies implicated the SmvRA efflux system (a transcriptionally regulated, inner membrane-associated efflux system) as a major determinant of resistance. This system is also implicated in resistance to two commercial bolaamphiphile antiseptics, octenidine and chlorhexidine, which was further validated herein. In sum, this work highlights, for the first time, a discrete inner-membrane specific mechanism for the bolaamphiphile class of disinfectants that contrasts with the prevailing model of indiscriminate membrane interactions of commercial amphiphiles paving the way for future innovations in disinfectant research.

Resistance patterns, virulence determinants, and biofilm genes of multidrug-resistant Pseudomonas aeruginosa isolated from fish and fish handlers.

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing.

Synergistic combinations of novel polymyxins and rifampicin with improved eradication of colistin-resistant Pseudomonas aeruginosa biofilms.

Background: Increased prevalence of antimicrobial resistance coupled with a lack of new antibiotics against Gram-negative bacteria emphasize the imperative for novel therapeutic strategies. Colistin-resistant Pseudomonas aeruginosa constitutes a challenge, where conventional treatment options lack efficacy, in particular for biofilm-associated infections. Previously, synergy of colistin with other antibiotics was explored as an avenue for the treatment of colistin-resistant infections, and recently we reported our efforts towards colistin analogs capable of combating planktonic colistin-resistant strains. Aims: The aim of the present study was to investigate whether analogs of polymyxin B with improved potency in wild-type and moderate resistant Gram-negative pathogens would retain similarly increased activity in highly colistin-resistant clinical P. aeruginosa isolates (in planktonic and biofilm growth) when applied alone and in combination with rifampicin. Materials and methods: In this in vitro study, we tested three analogs of polymyxin B prepared by solid-phase peptide synthesis. Antimicrobial susceptibility testing was performed by measurement of minimum inhibitory concentrations via the broth microdilution method. Interactions between two antimicrobials was quantified in a checkerboard broth microdilution assay by calculating the fractional inhibitory concentration index for each combination. For testing of antibiofilm activity a previously described model with alginate beads encapsulating a biofilm culture was applied. The minimum biofilm eradication concentrations (MBECs) were evaluated, and the fractional biofilm eradication concentration indices were calculated. Three recently identified colistin analogs (CEP932, CEP936 and CEP938) were tested against three isogenic pairs of colistin-susceptible and colistin-resistant P. aeruginosa clinical isolates as well as the reference strain PAO1. Results: For bacteria in planktonic growth CEP938 retained almost full potency in all three resistant isolates, while exhibiting similar activity as colistin in susceptible isolates. Against biofilms CEP938 was slightly more potent against PAO1 as compared to colistin, while also retaining activity against a biofilm of the colistin-resistant strain 41,782/98. Next, synergy between CEP938 and the antibiotic rifampicin was explored. Interestingly, CEP938 did not exhibit synergy with rifampicin in planktonic cultures. Importantly, for colistin-resistant biofilms the CEP938-rifampicin combination demonstrated activity superior to that found for the colistin-rifampicin combination. Conclusions: The present study showed in vitro efficacy of CEP938 against both colistin-susceptible and colistin-resistant P. aeruginosa biofilms as well as an ability of CEP938 to synergize with rifampicin in biofilm eradication.

Enhanced denitrification by sunlight-hematite: A neglected nitrogen flow pattern in red soil.

Mineral-microbe interactions in the Earth's Critical Zone significantly influence elemental biogeochemical cycling and energy flow processes. This study addresses the key scientific question of how semiconducting minerals drive microbial nitrogen cycling. In the red soil environment, the presence of semiconducting minerals enhances the denitrification process mediated by facultative microorganisms (Pseudomonas aeruginosa PAO1) with denitrifying activity. Compared to darkness, light significantly enhanced the synergistic denitrification kinetic process of red soil and Pseudomonas aeruginosa PAO1 (1.87 times). Cyclic voltammetry shows that the P. aeruginosa PAO1-red soil synergistic system exhibits distinct redox peaks under light. The constant potential current curve and electrochemical impedance spectroscopy measurements reveal a high photocurrent density (1.0 µA/cm2) and minimal polarization resistance (102 Ω) under this condition. These findings confirm that the sunlight-red soil-P. aeruginosa PAO1 synergistic process has excellent electron generation and migration capacity, active redox reactions, and good electron compatibility. Additionally, the photoelectrons of semiconductive minerals in red soil profoundly impact the metabolic processes of microbial denitrification functional genes. Using real-time polymerase chain reaction (qPCR) gene array technology, the abundance of nitrogen metabolism functional genes in P. aeruginosa PAO1 increased by 200 % during the light-red soil synergistic process. Notably, denitrification-related genes (ureC, nirS1, gdhA, and nosZ2) were significantly upregulated. This study confirms that semiconducting minerals are involved in the nitrogen cycle pathway of microbial denitrification and supplements the theory of mineral-microbial synergistic element biogeochemical cycling in the natural environment.

Antibacterial activity and mechanism of colistin-loaded polymeric nanoparticles for combating multidrug-resistant Pseudomonas aeruginosa biofilms: A synergistic approach.

Multidrug-resistant P. aeruginosa (MDR-P. aeruginosa), associated with elevated morbidity, mortality, and readmission rates, presents a formidable challenge to eradication due to its robust resistance to antimicrobial agents and biofilm formation. Herein, self-assembling nanoparticles (NO-PE/PLL NPs) comprised of NO donor-conjugated γ-polyglutamic acid (GSNO-PGA), epsilon-poly-l-lysine (PLL) and colistin were fabricated. The negatively charged NO-PE/PLL NPs exhibited effective penetration through airway mucus, reaching the infection site where GSNO-PGA released NO in response to glutathione within biofilm. PLL worked synergistically with colistin (fractional inhibitory concentration index: 0.281), reducing the minimum inhibitory concentration (MIC) of colistin from 2 to 0.5 µg/mL. Benefiting from this synergistic antibacterial action and NO-mediated biofilm disruption, NO-PE/PLL NPs achieved a 99.99 % eradication rate against MDR-P. aeruginosa biofilms. Additionally, NO-PE/PLL NPs efficiently inhibited endotoxins-stimulated inflammation response. In a chronic pulmonary infection model, NO-PE/PLL NPs displayed the highest eradication efficiency (99.78 %) to infected mice, while having no adverse effects on their major organs or pulmonary functions. These results highlight NO-PE/PLL NPs as a promising therapeutic strategy for treating recalcitrant infections caused by MDR-P. aeruginosa biofilms.

Insight into the outer membrane asymmetry of P. aeruginosa and the role of MlaA in modulating the lipidic composition, mechanical, biophysical, and functional membrane properties of the cell envelope.

In Gram-negative bacteria, the outer membrane (OM) is asymmetric, with lipopolysaccharides (LPS) in the outer leaflet and glycerophospholipids (GPLs) in the inner leaflet. The asymmetry is maintained by the Mla system (MlaA-MlaBCDEF), which contributes to lipid homeostasis by removing mislocalized GPLs from the outer leaflet of the OM. Here, we ascribed how Pseudomonas aeruginosa ATCC 27853 coordinately regulates pathways to provide defense against the threats posed by the deletion of mlaA. Especially, we explored (i) the effects on membrane lipid composition including LPS, GPLs, and lysophospholipids, (ii) the biophysical properties of the OM such as stiffness and fluidity, and (iii) the impact of these changes on permeability, antibiotic susceptibility, and membrane vesicles (MVs) generation. Deletion of mlaA induced an increase in total GPLs and a decrease in LPS level while also triggering alterations in lipid A structures (arabinosylation and palmitoylation), likely to be induced by a two-component system (PhoPQ-PmrAB). Altered lipid composition may serve a physiological purpose in regulating the mechanobiological and functional properties of P. aeruginosa. We demonstrated an increase in cell stiffness without alteration of turgor pressure and inner membrane (IM) fluidity in ∆mlaA. In addition, membrane vesiculation increased without any change in OM/IM permeability. An amphiphilic aminoglycoside derivative (3',6-dinonyl neamine) that targets P. aeruginosa membranes induced an opposite effect on ∆mlaA strain with a trend toward a return to the situation observed for the WT strain. Efforts dedicated to understanding the crosstalk between the OM lipid composition, and the mechanical behavior of bacterial envelope, is one needed step for designing new targets or new drugs to fight P. aeruginosa infections.IMPORTANCEPseudomonas aeruginosa is a Gram-negative bacterium responsible for severe hospital-acquired infections. The outer membrane (OM) of Gram-negative bacteria acts as an effective barrier against toxic compounds, and therefore, compromising this structure could increase sensitivity to antibiotics. The OM is asymmetric with the highly packed lipopolysaccharide monolayer at the outer leaflet and glycerophospholipids at the inner leaflet. OM asymmetry is maintained by the Mla pathway resulting in the retrograde transport of glycerophospholipids from the OM to the inner membrane. In this study, we show that deleting mlaA, the membrane component of Mla system located at the OM, affects the mechanical and functional properties of P. aeruginosa cell envelope. Our results provide insights into the role of MlaA, involved in the Mla transport pathway in P. aeruginosa.

Evaluation of Antimicrobial Resistance Patterns of Pseudomonas aeruginosa Strains Isolated among COVID-19 Patients in Brazil Typed by Fourier-Transform Infrared Spectroscopy.

This study aimed to characterize Pseudomonas aeruginosa strains isolated from hospitalized patients during the COVID-19 pandemic. This was achieved using phenotypic and molecular techniques, including their antimicrobial resistance profile and biofilm formation. Eighteen strains were isolated from a hospital in Rio de Janeiro, Brazil, and identified by VITEK®2, MALDI-TOF/MS (VITEK MS® and MALDI Biotyper®), and 16S rRNA sequencing. Fourier-transform infrared (FTIR) spectroscopy, antimicrobial susceptibility testing, and biofilm formation and disinfectant tolerance tests were applied to evaluate the virulence characteristics of the strains. VITEK®2 (≥99%), VITEK MS® (≥82.7%), and MALDI Biotyper® (score ≥ 2.01) accurately identified the P. aeruginosa strains, but 16S rRNA sequencing did not differentiate the species P. aeruginosa from P. paraeruginosa. FTIR typing identified three different clusters, but no correlation between the phenotypical or antimicrobial susceptibility testing patterns was found. Most strains exhibited resistance to various antimicrobials. The exceptions were sensitivity to amikacin and norfloxacin, and consequently, these could be considered potential treatment options. Most strains (n = 15, 83.3%) produced biofilms on polystyrene. Sodium hypochlorite treatment (0.5%/15 min) was shown to be the most effective disinfectant for biofilm elimination. P. aeruginosa biofilm formation and tolerance to disinfectants demonstrate the need for effective cleaning protocols to eliminate contamination by this organism in the hospital environment and medical equipment.

Emergence of NDM-1-Producing Pseudomonas aeruginosa Nosocomial Isolates in Attica Region of Greece.

Here, we report on the emergence and spread of multidrug-resistant NDM-1-producing P. aeruginosa isolates from patients hospitalized in the Attica region, Greece, in 2022 to provide data on their resistome, their virulome, the genetic environment of blaNDM-1, and their molecular epidemiology. A total of 17 carbapenem-resistant P. aeruginosa isolates identified as NDM-producers by immunochromatography at the hospital level were sent to the Central Public Health Laboratory, in the frame of the laboratory surveillance of carbapenem-resistant pathogens, for further characterization. The initial screening for genetic AMR determinants was carried out by PCR and the MDR Direct Flow Chip assay. Typing was performed by MLST and DLST, the latter in a subset of isolates. Further analysis was performed by whole-genome sequencing (WGS) of six isolates from both hospitals to analyze their entire genomes and elucidate their genetic relatedness. All isolates were allocated to international high-risk clones, sixteen to ST773 and one to ST308. Five ST773 and the sole ST308 isolate were found to harbor the blaNDM-1 gene, along with various other ARGs integrated into their chromosomes, as well as with a wide variety of virulence genes. The blaNDM-1 gene was located in the integrative and conjugative elements ICE6600-like and ICETn43716385 in ST773 and ST308 isolates, respectively. Single-nucleotide polymorphism analysis of the five ST773 isolates indicated their clonal spread in both hospitals. These results suggested that two different molecular events contributed to the emergence of NDM-1-producing P. aeruginosa isolates in Athenian hospitals, highlighting the need for ongoing surveillance.

Structure-Based Discovery of Symmetric Disulfides from Garlic Extract as Pseudomonas aeruginosa Quorum Sensing Inhibitors.

Microorganisms are the most common cause of food spoilage. Pseudomonas aeruginosa is a common foodborne pathogen that causes food spoilage and poses a serious threat to food safety. As a crucial target in antitoxicity strategies, the quorum sensing (QS) system shows promising potential for further development. The garlic extract diallyl disulfide exhibits inhibitory activity against the QS system of P. aeruginosa, with disulfide bonds serving as the active component. However, the biological activity of other symmetric disulfides has not been investigated in this capacity. The study synthesized 39 disulfide bond-containing analogs and evaluated their activity as quorum sensing inhibitors (QSIs). The results showed that p-hydroxyphenyl substitution can replace the allyl groups while maintaining strong biological activity. The virulence factors production was reduced by compound 2i, with the strongest inhibitory effect being observed on elastase production. Synergistic inhibition was observed in the presence of antibiotics like ciprofloxacin and tobramycin. 2i successfully inhibited P. aeruginosa infection in the Galleria mellonella larvae model. Primary mechanism studies using transcriptome, surface plasmon resonance and molecular docking suggested that 2i inhibits the QS system by targeting the LasR protein. Thus, compound 2i could be used in developing QSIs for the control of P. aeruginosa infections.

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.

Simultaneous clonal spread of NDM-1-producing Pseudomonas aeruginosa ST773 from Ukrainian patients in the Netherlands and Spain.

Objectives: We describe the clonal spread of New Delhi metallo-ß-lactamase (NDM) 1-producing Pseudomonas aeruginosa isolates belonging to the ST773 clone in Spain and the Netherlands, associated with the transfer of Ukrainian patients during the war. Methods: Between March and December 2022, nine NDM-1-producing P. aeruginosa ST773 isolates were recovered from nine Ukrainian patients evacuated to two Spanish (n = 3) and five Dutch (n = 6) hospitals. Antimicrobial susceptibility testing was studied (Sensititre, Microscan, EUCAST-2023). Whole genome sequencing (Illumina, Oxford-Nanopore) was used to analyze the genetic relatedness, the resistome, and the prophage content. Results: All NDM-1-producing P. aeruginosa ST773 isolates exhibited resistance to all tested antimicrobials except colistin, aztreonam, and cefiderocol. Genomic analysis revealed that all isolates had an identical resistome and a chromosomally encoded integrative conjugative element carrying the bla NDM-1 gene. The core genome multilocus sequence typing and core genome single nucleotide polymorphisms analysis showed highly related isolates, irrespective of country of isolation, distant from other NDM-1-ST773 P. aeruginosa not collected in Ukraine. Both analysis revealed two closely related clusters, spanning the Spanish and Dutch isolates. In addition, a high content of prophages was identified in all strains, most of them in more than one isolate simultaneously, regardless of their origin country. Moreover, an identical phage tail-like bacteriocin cluster was identified in all NDM-1-ST773 P. aeruginosa. Conclusions: We report a clonal dissemination of NDM-producing P. aeruginosa ST773 to the Netherlands and Spain associated with patients from Ukraine. Our work highlights the importance of genomic surveillance and to understand the dynamics of resistance in multidrug-resistant bacteria after the transfer of patients from conflict zones. International collaboration is crucial to address global antimicrobial resistance.

Impeding microbial biofilm formation and Pseudomonas aeruginosa virulence genes using biologically synthesized silver Carthamus nanoparticles.

Long-term antibiotic treatment results in the increasing resistance of bacteria to antimicrobials drugs, so it is necessary to search for effective alternatives to prevent and treat pathogens that cause diseases. This study is aimed for biological synthesis of silver Carthamus nanoparticles (Ag-Carth-NPs) to combat microbial biofilm formation and Pseudomonas aeruginosa virulence genes. Ag-Carth-NPs are synthesized using Carthamus tenuis aqueous extract as environmentally friendly method has no harmful effect on environment. General factorial design is used to optimize Ag-Carth-NPs synthesis using three variables in three levels are Carthamus extract concentration, silver nitrate concentration and gamma radiation doses. Analysis of response data indicates gamma radiation has a significant effect on Ag-Carth-NPs production. Ag-Carth-NPs have sharp peak at λ max 425 nm, small and spherical particles with size 20.0 ± 1.22 nm, high stability up to 240 day with zeta potential around - 43 ± 0.12 mV, face centered cubic crystalline structure and FT-IR spectroscopy shows peak around 620 cm-1 that corresponding to AgNPs that stabilized by C. tenuis extract functional moiety. The antibacterial activity of Ag-Carth-NPs against pathogenic bacteria and fungi was determined using well diffusion method. The MIC values of Ag-Carth-NPs were (6.25, 6.25, 3.126, 25, 12.5, 12.5, 25 and 12.5 µg/ml), MBC values were (12.5, 12.5, 6.25, 50, 25, 25, 50 and 25 µg/ml) and biofilm inhibition% were (62.12, 68.25, 90.12, 69.51, 70.61, 71.12, 75.51 and 77.71%) against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Candida tropicalis and Candida albicans respectively. Ag-Carth-NPs has bactericidal efficacy and significantly reduced the swarming, swimming motility, pyocyanin and protease production of P. aeruginosa. Furthermore, P. aeruginosa ToxA gene expression was significantly down regulated by 81.5%, while exoU reduced by 78.1%, where lasR gene expression reduction was 68%, while the reduction in exoU was 66% and 60.1% decrease in lasB gene expression after treatment with Ag-Carth-NPs. This activity is attributed to effect of Ag-Carth-NPs on cell membrane integrity, down regulation of virulence gene expression, and induction of general and oxidative stress in P. aeruginosa. Ag-Carth-NPs have no significant cytotoxic effects on normal human cell (Hfb4) but have IC50 at 5.6µg/mL against of HepG-2 cells. Limitations of the study include studies with low risks of silver nanoparticles for in vitro antimicrobial effects and its toxicity.

Determination of the presence of carbapenemase enzymes in carbapenem-resistant Pseudomonas aeruginosa isolates by susceptibility test based algorithm.

PURPOSE: Phenotypic methods have been proposed for the detection of carbapenemase production. These tests can have slower turnaround times. With the sensitivity-based algorithm described by Gill et al. will be possible to detect the carbapenemase. METHODS: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates from three hospitals between January 2017 and December 2021 were included. The modified carbapenemase-inactivation-method(mCIM) and two algorithms were used, defined as "primary algorithm, i.e. ceftazidime and cefepime non-susceptible in addition to imipenem or meropenem resistance" and "secondary algorithm, i.e. ceftolozane/tazobactam non-susceptible in addition to imipenem or meropenem resistance". PCR testing was performed on all isolates. RESULTS: 256 CRPA isolates were included in the study. When the primary or secondary algorithm criteria were applied, there were 173 isolates that met one or both of them. Of these, 29 were CIM-positive isolates. CONCLUSION: In our study, the use of the algorithm reduced the need for CIM testing by 32 %.

Relationship between antimicrobial use and the highest number of multidrug-resistant-Pseudomonas aeruginosa: a 10-year study.

INTRODUCTION: Multi-drug-resistant (MDR) Pseudomonas aeruginosa is a dangerous pathogen causing nosocomial infection, particularly in low- and middle-income countries like Brazil. This retrospective study at a Brazilian university hospital examined the relationship between antimicrobial use and MDR-P. aeruginosa. METHODOLOGY: Data was collected from 358 patients with non-repetitive P. aeruginosa infections from 2009 to 2019. Antibiotic use was measured in grams and expressed as defined daily dose (DDD) per 1000 patient-days for meropenem, imipenem, polymyxin, and tigecycline. RESULTS: Extensively drug-resistant (XDR) P. aeruginosa occurred in 36.1%, and MDR in 32.6% of cases. Risk factors for XDR infection were hospitalization prior to infection (OR = 0.9901), intensive care unit (ICU) admission (OR = 0.4766), previous antibiotic use (OR = 1.4417), and use of cefepime (OR = 0.3883). Over the ten-year period, utilization of the monitored antibiotics increased, and there was a positive correlation between the rise in MDR-P. aeruginosa and the consumption of ceftriaxone, imipenem, meropenem, and polymyxin B. The 30-day mortality rate was 40.0% for all patients and 41.0% for those infected with XDR-P. aeruginosa. CONCLUSIONS: This study highlights the negative impact of the indiscriminate use of antimicrobials, which has led to a significant increase in multidrug-resistant P. aeruginosa strains in hospitals.

Synergy between Lactobacillus murinus and anti-PcrV antibody delivered in the airways to boost protection against Pseudomonas aeruginosa.

Therapeutic antibodies (Ab) have revolutionized the management of multiple illnesses including respiratory tract infections (RTIs). However, anti-infectious Ab displayed several limitations including antigen restrictiveness, narrowed therapeutic windows, and limited dose in the vicinity of the target when delivered by parenteral routes. Strategies enhancing further Ab-dependent containment of infection are currently needed. Here we showed that a combination of inhaled anti-infectious Ab and probiotics is an efficient formulation to protect against lung infection. Using a mouse model of Pseudomonas aeruginosa-induced pneumonia, we demonstrated a synergistic effect reducing both bacterial burden and pro-inflammatory response affording protection against primary and secondary infections. This is the first study showing that the local combination in the airways of anti-infective Ab and probiotics subverts suboptimal potency of Ab monotherapy and provides protection against respiratory pathogen.

Role of factor H-related protein 3 in Pseudomonas aeruginosa bloodstream infections.

Pseudomonas aeruginosa is a leading cause of nosocomial bloodstream infections. The outcome of these infections depends on the virulence of the microorganism as well as host-related conditions and factors. The complement system plays a crucial role in defense against bloodstream infections. P. aeruginosa counteracts complement attack by recruiting Factor H (FH) that inhibits complement amplification on the bacterial surface. Factor H-related proteins (FHRs) are a group of plasma proteins evolutionarily related to FH that have been postulated to interfere this bacterial evasion mechanism. In this study, we demonstrate that FHR-3 competes with purified FH for binding to P. aeruginosa and identify EF-Tu as a common bacterial target for both complement regulator factors. Importantly, elevated levels of FHR-3 in human serum promote complement activation, leading to increased opsonization and killing of P. aeruginosa. Conversely, physiological concentrations of FHR-3 have no significant effect. Our findings suggest that FHR-3 may serve as a protective host factor against P. aeruginosa infections.

Luminescent Ln(III)-Metallopeptide Sensors for Monitoring Pseudomonas aeruginosa Elastase B Activity in Complex Biological Media.

The detection and monitoring of Pseudomonas aeruginosa and its virulence factors, such as the LasB protease, are crucial for managing bacterial infections. Traditional fluorescent sensors for this protease face limitations in bacterial cultures due to interference from pigments like pyoverdine secreted by this opportunistic pathogen. We report here a Ln(III)-metallopeptide that combines a DO3A-Ln(III) complex and a sensitizing unit via a short peptide sequence as a simple, tunable, and selective probe for detecting P. aeruginosa's LasB. The probe's luminescence switches off in the presence of P. aeruginosa's secretome due to LasB cleavage but remains stable in other bacterial environments, such as non-LasB-secreting P. aeruginosa strains or E. coli cultures. It also resists degradation by other proteases, like human leukocyte elastase and trypsin, and remains stable in the presence of bioanalytes related to P. aeruginosa infections, such as glutathione, H2O2, and pyocyanin, and in complex media like FBS. Importantly, time-gated experiments completely remove the background fluorescence of P. aeruginosa pigments, thus demonstrating the potential of the developed Ln(III)-metallopeptide for real-time monitoring of LasB activity in bacterial cultures.

Design, synthesis, and molecular dynamic simulations of some novel benzo[d]thiazoles with anti-virulence activity against Pseudomonas aeruginosa.

Inhibition of quorum sensing (QS) is an impending approach for targeting bacterial infection. Fourteen benzo[d]thiazole and 2-pyrazolo[1,5-a]pyrimidin-3-yl)benzo[d]thiazoles analogues were designed and synthesized as promising LasR antagonists with QS inhibition activity. Among the investigated compounds, compounds 3c, 3e, and 8d exhibited the highest percentage inhibition in biofilm formation (77 %, 63.9 %, 69.4 %), pyocyanin production (74.6 %, 64.9, 69.4 %), and rhamnolipids production (58.5 %, 51 %, 54.3 %) in P. aeruginosa, respectively. Additionally, compounds 3c, 3e and 8d achieved IC50 values against Las R equal 1.37 ± 0.35, 1.55 ± 0.24, 1.1 ± 0.15 µM respectively. Also, molecular docking of the target compounds into the LasR binding site co-crystalized "odDHL" revealed their binding with the essential residues for protein inhibition. Additionally, molecular dynamics simulation (MDS) experiments over 200 ns of compound 3c showed its ability to interact with the LasR binding site with dissociation of the protein's dimer confirming its action as a LasR antagonist. The obtained findings inspire further investigation for benzo[d]thiazole and 2-pyrazolo[1,5-a]pyrimidin-3-yl)benzo[d]thiazoles aiming to design and synthesize more potential QS inhibitors.

Complete genome sequence of Pseudomonas aeruginosa Y010, a taro rhizosphere strain producing potent antimicrobial agents.

Pseudomonas aeruginosa Y010, isolated from the taro rhizosphere, exhibits great antagonistic abilities against Dickeya strains that cause soft-rot and blackleg diseases of plants by producing potent antimicrobial agents. The complete genome of Y010 was sequenced and annotated, which is 6,415,628 bp in length with 66.39% GC content.