Pseudomonas aeruginosa Biofilms

Multifaceted quorum-sensing inhibiting activity of 3-(Benzo[d][1,3]dioxol-4-yl)oxazolidin-2-one mitigates Pseudomonas aeruginosa virulence

As antibiotic resistance escalates into a global health crisis, novel therapeutic approaches against infectious diseases are in urgent need. Pseudomonas aeruginosa, an adaptable opportunistic pathogen, poses substantial challenges in treating a range of infections. The quorum-sensing (QS) system plays a pivotal role in orchestrating the production of a large set of virulence factors in a cell density-dependent manner, and the anti-virulence strategy targeting QS may show huge potential. Here, we present a comprehensive investigation into the potential of the synthesized compound 3-(benzo[d][1,3]dioxol-4-yl)oxazolidin-2-one (OZDO, C10H9NO4) as a QS inhibitor to curb the virulence of P. aeruginosa. By employing an integrated approach encompassing in silico screening, in vitro and in vivo functional identification, we elucidated the multifaceted effects of OZDO. Molecular docking predicted that OZDO interfered with three core regulatory proteins of P. aeruginosa QS system. Notably, OZDO exhibited significant inhibition on the production of pyocyanin, rhamnolipid and extracellular proteases, biofilm formation, and cell motilities of P. aeruginosa. Transcriptomic analysis and quantitative real-time PCR displayed the down-regulation of QS-controlled genes in OZDO-treated PAO1, reaffirming the QS-inhibition activity of OZDO. In vivo assessments using a Caenorhabditis elegans-infection model demonstrated OZDO mitigated P. aeruginosa pathogenicity, particularly against the hypervirulent strain PA14. Moreover, OZDO in combination with polymyxin B and aztreonam presented a promising avenue for innovative anti-infective therapy. Our study sheds light on the multifaceted potential of OZDO as an anti-virulence agent and its significance in combating P. aeruginosa-associated infections.

Guanosine enhances the bactericidal effect of ceftiofur sodium on Streptococcus suis by activating bacterial metabolism

The emergence and rapid development of antibiotic resistance poses a serious threat to global public health. Streptococcus suis (S. suis) is an important zoonotic pathogen, and the development of its antibiotic resistance has made the infections difficult to treat. The combination of non-antibiotic compounds with antibiotics is considered a promising strategy against multidrug-resistant bacteria. However, the mechanism by which metabolites act as antibiotic adjuvant remains unclear. Here, we found that guanosine metabolism was repressed in multidrug-resistant S. suis. Exogenous guanosine promoted the antibacterial effects of ceftiofur sodium (CEF) in vitro and in vivo. Furthermore, we demonstrated that exogenous guanosine promoted the biosynthesis of purine pathway, TCA cycle and bacterial respiration, which make bacteria more sensitive to the killing effect of antibacterial. In addition, the function of the cell membrane is affected by guanosine and the accumulation of antimicrobials in the bacteria increased. Bacterial-oxidative stress and DNA damage induced by guanosine is also one of the mechanisms by which the antibacterial effect is enhanced. These results suggest that guanosine is a promising adjuvant for antibacterial drugs and provide new theoretical basis for the clinical treatment of S. suis infection.

Aqueous extracts of Moringa oleifera and Cinnamomum cassia as promising sources of antibiofilm compounds against mucoid and small colony variants of Pseudomonas aeruginosa and Staphylococcus aureus

Bacterial biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa pose significant challenges in treating cystic fibrosis (CF) airway infections due to their resistance to antibiotics. New therapeutic approaches are urgently needed to treat these chronic infections. This study aimed to investigate the antibiofilm potential of various plant extracts, specifically targeting mucoid and small colony variants of P. aeruginosa and S. aureus and strains. Moreover, it aimed to gain insights into the mechanisms of action and the potential phytochemicals responsible for antibiofilm activity. Solid-liquid extractions were performed on seven biomasses using water and ethanol (70 and 96 %) under controlled conditions, resulting in 21 distinct plant extracts. These extracts were evaluated for extraction yield, antioxidant activity, phenolic content, chemical composition by HPLC-TOF-MS, and antibiofilm activity using a 96-well plate assay, followed by crystal violet staining, bacterial adhesion assessment, and brightfield microscopy. Our findings revealed that aqueous extracts exhibited the highest inhibition of biofilm formation, with cinnamon bark and moringa seeds showing strong antibiofilm activity against both bacterial species. Brightfield microscopy confirmed that these extracts effectively inhibited biofilm formation. Chemical analysis identified key bioactive compounds, including moringin, benzaldehyde, coumarin, and quinic acid, which likely contribute to the observed antibiofilm effects. Recognizing that the antibiofilm properties of moringin, a common compound in both moringa seed and cinnamon bark extracts, remain underexplored, we conducted potential target identification via PharmMapper and molecular docking analyses to provide a foundation for future research. Computational analyses indicated that moringin might inhibit aspartate-semialdehyde dehydrogenase in P. aeruginosa and potentially interact with an unknown target in S. aureus. In conclusion, moringa seed and cinnamon bark extracts demonstrated significant potential for developing new therapies targeting biofilm-associated infections in CF. Further studies are needed to validate the computational predictions, identify the bacterial targets, and elucidate the precise mechanisms behind moringin's antibiofilm activity, which is likely the potential key contributor to the observed activity of the moringa and cinnamon bark extracts.

The effect of quaternary ammonium compounds (QACs) on quorum sensing and resistance of P. aeruginosa in clinical settings

Pseudomonas aeruginosa, a formidable opportunistic pathogen, is notorious for its ability to form biofilms and produce virulence factors that favor chronic infections, especially in cystic fibrosis patients. The misuse of disinfectants, combined with environmental leakage and biodegradation, has led to widespread exposure of microorganisms to sub-lethal concentrations of disinfectants, particularly quaternary ammonium compounds (QACs). This study investigates the interaction between QACs, specifically ethylbenzalkyl dimethyl ammonium chloride (EBAC), and the quorum sensing (QS) mechanisms governing P. aeruginosa behavior. The results demonstrate that exposure to sub-minimum inhibitory concentrations (sub-MICs) of EBAC not only enhances the biofilm-forming capability of P. aeruginosa isolates but also modulates the expression of crucial QS-regulated genes. Notably, the bacteria exhibit increased production of biofilm-associated virulence factors such as pyocyanin and elastase, and altered antibiotic susceptibility profiles, indicating a shift towards persistent infection phenotypes. These findings reveal that QAC exposure can significantly increase resistance to antibiotics and external stressors like hydrogen peroxide. These results emphasize the need to reassess the efficacy of QACs in clinical disinfection settings, particularly against P. aeruginosa infections, and highlight the potential for unintended consequences of their use regarding bacterial behavior and virulence. This study provides novel insights into the role of QACs in modulating QS-mediated virulence and antibiotic resistance, offering a new perspective on the risks associated with sub-lethal disinfectant exposure.

Novel synthesis and anti-pathogenic properties of ensifentrine and its intermediates against Pseudomonas aeruginosa

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder marked by persistent lung inflammation and airway constriction. It presents a formidable global health challenge owing to its high morbidity and mortality rates. It is often aggravated by infections from pathogens such as Pseudomonas aeruginosa, a predominant pathogen that accelerates lung function deterioration and triggers frequent exacerbations. Ensifentrine (ENF) exhibits strong anti-inflammatory effects and is a selective dual inhibitor of the enzymes PDE3 and PDE4, which have been reported to be beneficial in treating COPD exacerbation. This study examined the anti-pathogenic activity of ENF against P. aeruginosa by adopting an innovative synthetic route. A series of intermediates were synthesized via the novel route, optimizing the yield and integrity of ENF. Further investigations to determine the activity of the compound against P. aeruginosa involved antibacterial and antibiofilm testing and identification of the potential mechanisms of action. Preliminary results demonstrate that ENF and its intermediate ENFA exhibit 50-60% robust biofilm-inhibition and biofilm-eradication effects at remarkably low concentrations of 3.9 μM and 7.9 μM, respectively. Furthermore, ENF disrupts quorum sensing, leading to a 35% reduction in the production of pyoverdine and exopolysaccharide, which are two key virulence factors of P. aeruginosa. Importantly, ENF exhibits synergistic activity with ciprofloxacin, further enhancing its antimicrobial efficacy at a concentration of 0.25 μg mL-1. This study focuses on the innovative synthesis of ENF and its promising anti-pathogenic properties, which may make it an effective adjunctive treatment for COPD caused by P. aeruginosa.

Rapid and sensitive antimicrobial susceptibility testing of biofilm-forming bacteria using scalable paper-based organic transistors

A scalable, cost-effective paper-based organic field-effect transistor platform has been developed for rapid antimicrobial susceptibility testing (AST) of biofilm-forming pathogens. Traditional AST methods are costly, labor-intensive, and slow, with a lack of standardized biofilm models. This system directly tracks protons generated by biofilms, which serve as key indicators of bacterial metabolism under antibiotic exposure. A proton-sensitive PEDOT:PSS channel is employed, where metabolic proton activity de-dopes the transistor, reducing conductivity. The engineered paper substrate facilitates rapid, high-quality biofilm formation, improving assay reliability. The platform was validated on three clinically significant pathogens against frontline antibiotics, providing real-time, quantitative antibiotic efficacy profiles. Integrated with a microcontroller and machine learning algorithm, results are displayed on a liquid crystal display (LCD), classifying antibiotic concentration relative to the minimum inhibitory concentration with over 85% accuracy. This clinically translatable system offers a high-throughput, point-of-care solution for efficient infection management and antibiotic stewardship.

Flavourzyme Suppresses Pseudomonas aeruginosa Biofilms by Targeting Motility, Quorum Sensing, and Virulence Genes

The biofilm-mediated persistence of Pseudomonas aeruginosa in the food and biomedical sectors is currently a global concern. In light of this challenge, this study investigated a preventive approach against P. aeruginosa biofilm formation using Flavourzyme, a food-grade peptidase, considering its antibiofilm potential. The results revealed that a co-culture comprising 300 µL/mL (1 × minimum inhibitory concentration [MIC]) of Flavourzyme could kill P. aeruginosa. On the MBEC™ biofilm-forming device, 0.125 × MIC of Flavourzyme inhibited > 4.5 log CFU/peg of biofilm. Cell motilities and the biosynthesis of quorum sensing (QS) molecules such as N-acyl-homoserine lactones (AHLs), including C4-HSL, decreased significantly at 0.06 × MIC of Flavourzyme and became undetectable at 0.125 × MIC. Interestingly, while 0.03 × MIC of Flavourzyme elicited diverse expressions of QS and virulence-regulating genes, ≥ 0.06 × MIC of Flavourzyme remarkably suppressed the relative genomic expressions. This study proposes Flavourzyme as a potent antibiofilm agent against P. aeruginosa biofilms, recommending specific concentrations for effective use in food preservation.

Inhibition of acyl-homoserine-lactone synthase in Pseudomonas aeruginosa biofilms by 7-O-methyl-aromadendrin by using molecular docking and molecular dynamics simulation

This study investigates the potential of 7-O-methyl aromadendrin (7-OMA), a naturally occurring flavonoid-glycoside, as an inhibitor of acyl-homoserine-lactone (AHL) synthase in Pseudomonas aeruginosa, a key enzyme in quorum sensing and biofilm formation. Using molecular docking and molecular dynamics simulations, we evaluated the binding interactions and inhibitory effects of 7-OMA on AHL synthase. Molecular docking revealed a suitable binding affinity (-6.66 kcal/mol) between 7-OMA and the enzyme, with interactions at critical active site residues. Molecular dynamics simulations demonstrated that 7-OMA stabilizes the enzyme through hydrogen bonds and van der Waals interactions while enhancing its structural flexibility. The average RMSD of AHL synthase increased slightly in the presence of 7-OMA, indicating partial instability of the enzyme. Additionally, the average Rg value increased, suggesting that 7-OMA may expand the enzyme structure or reduce its compactness. MM-PBSA analysis confirmed the strength of these interactions, with favorable van der Waals and electrostatic contributions to the binding energy. These results suggest that 7-OMA disrupts the structural dynamics of AHL synthase, potentially inhibiting biofilm formation and reducing the virulence of Pseudomonas aeruginosa. The findings highlight the therapeutic potential of 7-OMA as a novel inhibitor of AHL synthase, offering a promising strategy to combat biofilm-associated infections. Future studies should focus on evaluating the bioavailability, in vivo efficacy, and clinical applicability of 7-OMA, as well as its broader activity against other multidrug-resistant pathogens.

Graphical abstract

Chemical profile, virtual screening, and virulence-inhibiting properties of Sphagneticola trilobata L. essential oils against Pseudomonas aeruginosa

The escalating threat of microbial resistance underscores the urgent need for innovative solutions, including natural agents capable of attenuating virulence. This study explores the antimicrobial and anti-virulence potential of essential oils (EOs) derived from Sphagneticola trilobata against Pseudomonas aeruginosa. Through GC/MS analysis, volatile metabolites from the flower heads and leaves/stems of Egyptian S. trilobata were identified, revealing 43 and 62 components, respectively. Key compounds included α-phellandrene, α-pinene, D-limonene, and α-thujene. The Minimum Inhibitory Concentrations (MIC) of flower head and leaf/stem EOs against P. aeruginosa were 1.17% and 1.75% v/v, respectively. At sub-MIC doses (1/8th of the MIC), the EOs exhibited significant anti-virulence properties, including complete inhibition of protease activity and disruption of biofilm formation, which are crucial for bacterial survival and pathogenicity. Additionally, they effectively suppressed the expression of quorum sensing genes, which are essential for bacterial communication and virulence. Virtual screening of four major EO components (+)-(R)-limonene, (±)-α-pinene, α-phellandrene, and α-thujene against five critical protein targets involved in biofilm formation, quorum sensing, virulence, and protease activity in P. aeruginosa further supported their anti-virulence and antibiofilm actions, showing high affinity for these targets. These findings suggest that the EOs of S. trilobata hold great potential as natural virulence attenuating agents, particularly against biofilm-forming pathogens like P. aeruginosa.

Ultra-short lipopeptides containing d-amino acid exhibiting excellent stability and antibacterial activity against gram-positive bacteria

As novel antibacterial agents, antimicrobial peptides (AMPs) possess broad-spectrum antibacterial activity and low drug resistance, holding significant development potential. Nevertheless, the stability of AMPs significantly restricts their application. In light of this, we synthesized a series of ultra-short lipopeptides using d-amino acid substitution to enhance the stability of ultra-short lipopeptide C12-RRW-NH2 that was selected from our previous research while maintaining its antibacterial activity against gram-positive bacteria. Amongst, the ultra-short lipopeptide Lip7 (C12-rrw-NH2) with full d-amino acid demonstrated outstanding stability in protease, serum, and salt ion environments. It exerted excellent antibacterial activity against gram-positive bacteria, especially against methicillin-resistant Staphylococcus aureus (MRSA). Meanwhile, Lip7 presented a low propensity to develop bacterial resistance with potential for combination therapy with conventional antibiotics. Studies on its antibacterial mechanism revealed that Lip7 could rapidly depolarize the bacterial cytoplasmic membrane, disrupt the integrity of the bacterial membrane, lead to leakage of nucleic acid and protein, promote the generation of reactive oxygen species, and ultimately result in bacterial death. Additionally, Lip7 also exhibited therapeutic potential in both local and systemic MRSA-infected mice models with better safety in vivo. These findings highlighted that Lip7 is an ideal novel antibacterial alternative to offer guiding schemes for developing high-stability antimicrobial peptides to fight multidrug-resistant gram-bacteria.

Influence of Amino Acids on Quorum Sensing-Related Pathways in Pseudomonas aeruginosa PAO1: Insights from the GEM iJD1249

BACKGROUND/OBJECTIVES

Amino acids (AAs) play a critical role in diseases such as cystic fibrosis where Pseudomonas aeruginosa PAO1 adapts its metabolism in response to host-derived nutrients. The adaptation influences virulence and complicates antibiotic treatment mainly for the antimicrobial resistance context. D- and L-AAs have been analyzed for their impact on quorum sensing (QS), a mechanism that regulates virulence factors. This research aimed to reconstruct the genome-scale metabolic model (GEM) of P. aeruginosa PAO1 to investigate the metabolic roles of D- and L-AAs in QS-related pathways.

METHODS

The updated GEM, iJD1249, was reconstructed by using protocols to integrate data from previous models and refined with well-standardized in silico media (LB, M9, and SCFM) to improve flux balance analysis accuracy. The model was used to explore the metabolic impact of D-Met, D-Ala, D-Glu, D-Ser, L-His, L-Glu, L-Arg, and L-Ornithine (L-Orn) at 5 and 50 mM in QS-related pathways, focusing on the effects on bacterial growth and carbon flux distributions.

RESULTS

Among the tested AAs, D-Met was the only one that did not enhance the growth rate of P. aeruginosa PAO1, while L-Arg and L-Orn increased fluxes in the L-methionine biosynthesis pathway, influencing the metH gene. These findings suggest a differential metabolic role for D-and L-AAs in QS-related pathways.

CONCLUSIONS

Our results shed some light on the metabolic impact of AAs on QS-related pathways and their potential role in P. aeruginosa virulence. Future studies should assess D-Met as a potential adjuvant in antimicrobial strategies, optimizing the concentration in combination with antibiotics to maximize its therapeutic effectiveness.

Exploring the occurrence of Pseudomonas aeruginosa and comprehensive whole genome analysis of the bcsir_p4_s20 strain from municipal wastewater in Chattogram

Various studies reported the existence of multidrug-resistant (MDR) Pseudomonas aeruginosa in environmental samples, including hospital wastewater, municipal wastewater, and surface water. In this study, we investigated the impact of untreated municipal wastewater transmitting antibiotic-resistant P. aeruginosa strains in wastewater networks of Chattogram City, Bangladesh, through antibiotic susceptibility profiles and whole-genome sequencing (WGS) of the MDR P. aeruginosa bcsir_p4_s20. Forty-two P. aeruginosa isolates were identified from eight locations using polymerase chain reaction (PCR), targeting the oprI and oprL genes, and antibiotic susceptibility was determined against 11 antibiotics by the disc diffusion method. Resistant isolates were identified at all locations, with the highest resistance frequency displayed towards meropenem, cefepime, and colistin. The WGS of bcsir_p4_s20 was performed using the NextSeq 2000 platform. Several bioinformatics tools, like FastQC, Trimmomatic, SPAdes, and Prokka, were used for quality evaluation, low-quality read and adapter filtration, de novo assembly, and functional annotation. Comprehensive Antibiotic Resistance Database (CARD), AMRFinderPlus, and virulence factor database (VFDB) were employed to determine resistance genes and virulence factors. The strain belongs to the O7 serogroup and sequence type ST357. The analysis identified antibiotic resistance genes (blaPDC-11, sul1, and others) that cause resistance through efflux pump and inactivation mechanisms, and virulent genes responsible for adherence (flagella, type IV pili), enzyme (phospholipase C), iron uptake (pyoverdine), secretion system (exoT, exoU), and toxin (toxA) secretion. Therefore, municipal wastewater is a potential reservoir for MDR P. aeruginosa, and establishing wastewater treatment plants (WWTPs) at the primary source points before discharging it to the wastewater network is suggested to mitigate the risk of outbreaks.

Development and Characterization of LasR Immobilized Monolithic Column for Screening Active Ingredients as Quorum Sensing Inhibitors Against P. aeruginosa in Natural Products

Background and Aim

The enzyme/protein immobilized monolithic capillary combined with liquid chromatography-mass spectrometry is an efficient screening strategy for the corresponding agonist/antagonist. LasR is the potential therapeutic target since it plays a vital role in the colonization and invasion of Pseudomonas aeruginosa (P. aeruginosa). Therefore, reagents that inhibit LasR may be effective against P. aeruginosa. To screen and find LasR inhibitors rapidly, a LasR-immobilized monolithic capillary column was prepared and characterized.

Methods

Firstly, the recombinant LasR protein was prepared in E. coli. Then, the LasR protein was immobilized to the surface of poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine monolithic column. The affinity and stability of prepared column was also evaluated. Furthermore, the prepared column was applied to fishing LasR inhibitor in Scutellaria baicalensis Georgi extract. The interaction of the screening compound to LasR was confirmed through molecular docking.

Results

The recombinant active LasR protein was prepared in E. coli. After purification and validation, a comparative ligand fishing monolithic column was prepared through immobilizing LasR to the surface of the poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine through amidation reaction. The LasR was successfully immobilized to the monolithic column characterizing by Fourier transform infrared spectroscopy and scanning electron microscopy. The activity of immobilized LasR was reserved as it has affinity to the nature ligand 3-oxo-C12-HSL and stablied within 24 h at 4 °C. In the Scutellaria baicalensis Georgi extract, baicalein was screened as a potential LasR inhibitor. The molecular docking results and the in vivo evaluation confirmed the activity of baicalein.

Conclusion

The proposed LasR immobilized monolithic column is a viable strategy in screening LasR inhibitors. It can be considered as a possible alternative to traditional methods for screening LasR inhibitors as drug candidates against P. aeruginosa.

Biofilm detection in the food industry: Challenges in identifying biofilm eps markers and analytical techniques with insights for Listeria monocytogenes

Extracellular polymeric substances (EPS) in biofilms are promising targets for eradicating biofilms and monitoring their presence, especially in the food industry. For this understanding, the composition of the EPS matrix is crucial. Ideally, a biofilm marker is found serving both purposes, but such a compound has not yet been discovered. This review aims to identify general biofilm EPS markers distinct from planktonic cells, focusing on macromolecules in the EPS matrix. It also evaluates the feasibility of this goal across different bacterial groups and environmental conditions and discusses EPS analysis methods. This review digs deeper into the EPS matrix starting with an introduction to the EPS matrix itself and describing some of its influencing factors. Next, a brief description of cell-to-cell communication within biofilms is provided, as these interactions significantly influence the EPS matrix. The main part of this review describes the macromolecules inside the EPS matrix and attempts to find biofilm EPS markers applied to bacteria in general and specifically to Listeria monocytogenes as biofilms are a major contributor to its persistence. The last part of the review focuses on the analytical techniques available to characterize the EPS matrix. The review revealed that although multiple candidates showed great potential as biofilm markers, none were unique but ubiquitous in all bacteria tested. To achieve easy biofilm detection with current techniques, it's necessary to identify markers specific to the environmental conditions and common bacterial groups within each food category, sector, or facility, due to the lack of standardization in these techniques. This tailored approach ensures more accurate and effective biofilm monitoring. Moreover, the lack of standardized analytical techniques, including quantification techniques, complexifies studying the EPS matrix and developing monitoring and intervention strategies. Optimizing analytical techniques is crucial for this tailored approach, as it requires refined methods for detection, characterization, and quantification. This ensures the accurate identification of biofilm markers specific to environmental conditions and bacterial groups within each food sector.

The Role of Yinqiao Powder in Modulating Pseudomonas aeruginosa Biofilm and Virulence Factors

Purpose

It is now understood that the primary challenges in treating Pseudomonas aeruginosa (P. aeruginosa) infections are the secretion of multiple virulence factors, the formation of biofilm, and the emergence of multi-drug resistance. Small regulatory RNAs (sRNAs) and quorum sensing (QS) play an important role in regulating bacterial biofilms and multiple virulence factors, presenting potential targets for novel anti-P. aeruginosa therapies. Yinqiao Powder has demonstrated inhibitory activity against various bacteria and viruses. The objective of this study was to elucidate the precise mechanism of Yinqiao Powder's impact on P. aeruginosa virulence and to ascertain its clinical utility.

Methods

First, the effects of Yinqiao Powder on various virulence factors of P. aeruginosa were assessed through virulence phenotype experiments, including biofilm formation assay, pyocyanin production assay, rhamnolipid assay, and motility assay. Then, a cytotoxicity assay was used to evaluate the effect of P. aeruginosa treated by Yinqiao Powder on cells. Finally, an RT-qPCR assay was used to detect the effects of Yinqiao Powder on QS system and virulence-related gene expression.

Results

This study revealed that sub-minimum inhibitory concentration (sub-MIC) levels of Yinqiao Powder significantly inhibit biofilm formation, swarming motility, pyocyanin and rhamnolipid production in a dose-dependent manner. The cytotoxicity assay also confirmed that Yinqiao Powder weakened the cytotoxicity of P. aeruginosa. Furthermore, Yinqiao Powder was found to modulate the P. aeruginosa sRNA-QS-virulence network. Specifically, it repressed the lasI, the rhlI, and sRNA P27 while upregulating sRNA PhrD. Additionally, the phzA and pqsA genes, associated with pyocyanin and rhamnolipid/biofilm regulation, respectively, were repressed by Yinqiao Powder.

Conclusion

Yinqiao Powder effectively inhibits QS system-related regulatory genes, sRNAs, biofilm formation, swarming motility, pyocyanin and rhamnolipid production at specific concentrations. These results support the potential of Yinqiao Powder as a quorum-sensing inhibitor.

Regulatory Effects of RNA-Protein Interactions Revealed by Reporter Assays of Bacteria Grown on Solid Media

Reporter systems are widely used to study biomolecular interactions and processes in vivo, representing one of the basic tools used to characterize synthetic regulatory circuits. Here, we developed a method that enables the monitoring of RNA-protein interactions through a reporter system in bacteria with high temporal resolution. For this, we used a Real-Time Protein Expression Assay (RT-PEA) technology for real-time monitoring of a fluorescent reporter protein, while having bacteria growing on solid media. Experimental results were analyzed by fitting a three-variable Gompertz growth model. To validate the method, the interactions between a set of RNA sequences and the RNA-binding protein (RBP) Musashi-1 (MSI1) were evaluated, as well as the allosteric modulation of the interaction by a small molecule (oleic acid). This new approach proved to be suitable to quantitatively characterize RNA-RBP interactions, thereby expanding the toolbox to study molecular interactions in living bacteria, including allosteric modulation, with special relevance for systems that are not suitable to be studied in liquid media.

Aspirin enhances the antibacterial activity of colistin against multidrug-resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) Pseudomonas aeruginosa (PSA), recently reclassified by the World Health Organization (WHO) as a high-priority antimicrobial-resistant pathogen, continues to impose a substantial global health burden due to escalating resistance and stagnant therapeutic innovation. Colistin retains critical clinical utility against MDR P. aeruginosa infections; however, its dose-limiting nephrotoxicity and neurotoxicity necessitate strategies to optimise therapeutic indices. This study investigated the molecular mechanism underlying the synergistic activity of aspirin in potentiating colistin efficacy against MDR P. aeruginosa. In vitro analyses revealed marked synergistic bactericidal activity (FIC index ≤0.5), with metabolomic profiling demonstrating suppression of key metabolic pathways integral to bacterial membrane biogenesis, including glycerophospholipid metabolism and fatty acid biosynthesis. Ultrastructural imaging confirmed irreversible disruption of membrane integrity via combined treatment. In a rat model of P. aeruginosa-induced pneumonia, colistin-aspirin co-administration demonstrated superior efficacy to monotherapy, significantly reducing pulmonary bacterial load (3 to 4-log CFU/g reduction vs colistin alone; p < 0.01), attenuating histopathological injury, and suppressing pro-inflammatory cytokine levels (IL-6, IL-8, TNF-α) by 30-47%. Critically, this synergy enabled a reduction of colistin dosing to one-sixteenth while maintaining bactericidal potency. These findings provide mechanistic insights into aspirin-mediated colistin sensitisation and evidence supporting combinatorial regimens to circumvent colistin toxicity barriers. This work establishes a rational foundation for clinical translation of repurposed aspirin-colistin therapy against MDR P. aeruginosa infections.

Architecture of an embracing lipase-foldase complex of the type II secretion system of Acinetobacter baumannii

Acinetobacter baumannii is a major human pathogen responsible for a growing number of multi-antibiotic-resistant infections, and of critical priority for the World Health Organization (WHO). A. baumannii employs a type II secretion system (T2SS) to secrete toxins extracellularly to enable cytotoxicity and colonization. Lipase LipA, secreted by the A. baumannii T2SS, is required for virulence and fitness, and in the periplasm is maintained in an active state by its essential foldase, LipB. Here we report that LipA is able to recognize lipids of different chain lengths at extremes of pH and temperature, thanks to its stabilization by LipB through an extended, highly helical "embrace." A vast bioinformatic analysis indicates that LipB-like foldases are widespread over numerous proteobacteria, and thus the extended foldase architecture shown here could be widespread. These results provide new insight into A. baumannii's adaptability as a pathogen in different environments and could facilitate the development of novel antibacterials.

Synergistic action of mucoactive drugs and phages against Pseudomonas aeruginosa and Klebsiella pneumoniae

N-acetylcysteine (NAC) and ambroxol hydrochloride (AMB) are commonly prescribed alongside antibiotics to alleviate sputum retention in lower respiratory tract infections, which are often caused by bacterial pathogens. With the rising threat of antibiotic resistance, phage therapy has emerged as a promising alternative alongside. However, no studies have explored the potential interactions between phages and these mucoactive agents despite their frequent concurrent use during phage therapy. Therefore, investigating the potential synergy and its subsequent impact on phage infection dynamics could enhance clinical strategies for treating bacterial infections with phages. Our study utilized Pseudomonas aeruginosa strain ZS-PA-35 and Klebsiella pneumoniae strain Kp36, alongside their respective phages, to investigate their interactions in the presence of NAC or AMB. Our findings indicate that, under specific conditions, these mucoactive agents can function as adjuvants to lytic phages, enhancing bacterial susceptibility to phage infection and facilitating subsequent phage proliferation. Our study revealed that these synergistic interactions are strongly influenced by the physiological characteristics of the phages, the surrounding microenvironments, and the physiology of host tissues, as varying outcomes of phage-host interactions were observed among different phages and across distinct media. Taken together, our results emphasize the complexity of interactions between phages and NAC or AMB, underscoring the need for caution when using combination treatments.IMPORTANCEN-acetylcysteine (NAC) and ambroxol hydrochloride (AMB) are used in medical treatment of patients with acute and chronic bronchitis. Often, the choice of NAC or AMB is empirically determined by physicians. However, the potential impact of combining NAC or AMB with phage therapy remains unclear. To address this gap, a comprehensive understanding of their interplay is crucial to determine any potential synergistic effects. This study aims to elucidate how NAC or AMB influence phages targeting different receptors, thereby affecting their antibacterial activity against Pseudomonas aeruginosa and Klebsiella pneumoniae. Our results suggest that, under certain conditions, NAC or AMB provides an adjuvant effect by rendering the cells more susceptible to phage infection. These results contribute to advancing our understanding of the clinical combination of mucoactive agents and phage therapy, offering insights for optimizing treatment efficacy.

Two amino-substituted diphenyl fumaramide derivatives inhibit the virulence regulated by quorum sensing system of Pseudomonas aeruginosa

AIM

Pseudomonas aeruginosa employs the quorum sensing (QS) system, a sophisticated cell-to-cell communication mechanism, to modulate the synthesis and secretion of a range of virulence factors, which contribute to the establishment of acute or chronic infections in hosts. This study seeks to attenuate the virulence of P. aeruginosa by inhibiting the QS system, thereby reducing its pathogenicity as a promising alternative to traditional antibiotics.

METHODS AND RESULTS

Two compounds with an amino-substituted diphenyl fumaramide core, N1-(4-bromophenyl)-N4-(4'-oxo-3',4'-dihydro-1'H-spiro [cyclopentane-1,2'-quinazolin]-6'-yl) fumaramide (10D) and N1-(3-chloro-4-fluorophenyl)-N4-(4-oxo-3,4,4',5'-tetrahydro-1H,2'H-spiro [quinazoline-2,3'-thiophen]-6-yl) fumaramide (12A), were identified through in-silico screening. The QS inhibitory potential of both compounds was explored in vitro and in vivo. In in vitro experiments, neither compound exhibited bactericidal effects but significantly inhibited the production of QS-regulated extracellular protease and pyocyanin. Quantitative PCR analysis revealed that QS-activated genes and downstream virulence genes were transcriptionally suppressed by 10D or 12A. Molecular docking and molecular dynamics simulations predicted stable interactions between these compounds and the key QS regulators LasR and PqsR. When combined with polymyxin B, kanamycin, and levofloxacin, 10D and 12A exhibited synergistic antibacterial activity. Furthermore, compounds 10D and 12A significantly improved the survival of mice challenged with P. aeruginosa and effectively reduced the bacterial load in the lungs.

CONCLUSION

This study indicates that 10D and 12A possess considerable QS inhibitory potential, effectively attenuating the pathogenicity of P. aeruginosa. Moreover, the study offers structural insights and methodological guidance for the advancement of anti-virulence drug development.

Kaempferol Mitigates Pseudomonas aeruginosa-Induced Acute Lung Inflammation Through Suppressing GSK3β/JNK/c-Jun Signaling Pathway and NF-κB Activation

Background: Pseudomonas aeruginosa, one of the common bacterial pathogens causing nosocomial pneumonia, is characterized as highly pathogenic and multidrug-resistant. Kaempferol (KP), a natural flavonoid, has been shown to exhibit effectiveness in treating infection-induced lung injury. Methods: We applied network pharmacology to explore the underlying mechanisms of KP in treating P. aeruginosa pneumonia and further validated them through a mouse model of acute bacterial lung infection and an in vitro macrophage infection model. Results: The in vivo studies demonstrated that treatment with KP suppressed the production of proinflammatory cytokines, including TNF, IL-1β, IL-6, and MIP-2, and attenuated the neutrophil infiltration and lesions in lungs, leading to an increased survival rate of mice. Further studies revealed that KP treatment enhanced the phosphorylation of GSK3β at Ser9 and diminished the phosphorylation of JNK, c-Jun, and NF-κB p65 in lungs in comparison to the mice without drug treatment. Consistently, the in vitro studies showed that pretreatment with KP reduced the activation of GSK3β, JNK, c-Jun, and NF-κB p65 and decreased the levels of the proinflammatory cytokines in macrophages during P. aeruginosa infection. Conclusions: KP reduced the production of proinflammatory cytokines by inhibiting GSK3β/JNK/c-Jun signaling pathways and NF-κB activation, which effectively mitigated the P. aeruginosa-induced acute lung inflammation and injury, and elevated the survival rates of mice.

Pseudomonas aeruginosa aggregates elicit neutrophil swarming

Pseudomonas aeruginosa, a gram-negative multidrug-resistant (MDR) opportunist, belongs to the ESKAPE group of pathogens associated with the highest risk of mortality. Neutrophil swarming is a host defense strategy triggered by larger threats, where neutrophil swarms contain and clear damage/infection. Current ex vivo models designed to study neutrophil-pathogen interactions largely focus on individual neutrophil engagement with bacteria and fail to capture neutrophil swarming. Here, we report an ex vivo model that reproducibly elicits neutrophil swarming in response to bacterial aggregates. A rapid and robust swarming response follows engagement with pathogenic targets. Components of the type III secretion system (T3SS), a critical P. aeruginosa virulence determinant, are involved in swarm interaction. This ex vivo approach for studying neutrophil swarming in response to large pathogen targets constitutes a valuable tool for elucidating host-pathogen interaction mechanisms and for evaluating novel therapeutics to combat MDR infections.

Detecting Respiratory Pathogens for Diagnosing Lower Respiratory Tract Infections at the Point of Care: Challenges and Opportunities

Lower respiratory tract infections (LRTIs) are a leading cause of mortality worldwide, claiming millions of lives each year and imposing significant healthcare costs. Accurate detection of respiratory pathogens is essential for the effective management of LRTIs. However, this process often relies on sputum analysis, which requires extensive pretreatment steps. The viscous nature and complex composition of sputum present additional challenges, especially in settings where a rapid diagnosis at the point of care is essential. In this review, we describe the main types of LRTI, highlighting different patient care pathway and points of care. We review current methods for liquefying sputum samples and provide an overview of current commercially available diagnostic tools used in hospitals for LRTI detection. Furthermore, we critically review recent advancements in the literature focused on detecting respiratory pathogens and mechanisms of antimicrobial resistance in sputum, including nucleic acid amplification tests, immunoassays and other innovative approaches. Throughout the paper, we highlight challenges and opportunities associated with developing new biosensor technologies tailored for detecting respiratory pathogens in lower respiratory specimens. By shedding light on these pressing issues, we aim to inspire scientific community to create innovative diagnostic tools to address the urgent healthcare burden of lung diseases.

Phenazine Scaffolds as a Potential Allosteric Inhibitor of LasR Protein in Pseudomonas aeruginosa

Millions of individuals suffer from chronic infections caused by bacterial biofilms, resulting in significant loss of life. Pseudomonas aeruginosa stands out as a major culprit in causing such chronic infections, largely due to its antibiotic resistance. This pathogen poses a considerable threat in healthcare settings, particularly to critically ill and immunocompromised patients. The persistence of chronic and recurrent bacterial infections is often attributed to bacterial biofilms. Therefore, there is an urgent need to discover novel small molecules capable of efficiently eliminating biofilms independent of bacterial growth. In this project, an in silico drug discovery approach was employed to identify nine halogenated-phenazine compounds as allosteric inhibitors of the LasR protein. The LasR is a key transcription factor that triggers other quorum-sensing systems and plays a crucial role in biofilm formation and activation of virulence genes. By inhibiting LasR, specifically targeting its allosteric site, the dimerization of LasR and subsequent biofilm formation could be prevented. Molecular docking and simulations, coupled with binding energy calculations, identified five compounds with potential as anti-biofilm agents. These compounds exhibited higher binding affinities to the distal site, suggesting their structural capability to interact with allosteric site residues of the LasR protein. Based on these findings, it is proposed that these compounds could serve as promising leads for the treatment of biofilm and quorum-sensing-related infections.

Molecular modelling and experimental validation of mangiferin and its related compounds as quorum sensing modulators of Pseudomonas aeruginosa

The LasR quorum sensing system regulates the virulence factors of Pseudomonas aeruginosa, a multi-drug resistant pathogen. Mangiferin and related compounds have been found to modulate this system as determined by in silico and in vitro experimental procedures. ZINCPharmer was used to compile a library of over 1000 metabolites that were screened to the top five based on shared pharmacophores and drug-like properties with mangiferin. Molecular docking and molecular dynamics simulation (140 ns) showed that ZINC E (- 55.64 ± 2.93 kcal/mol) and ZINC D (- 54.51 ± 2.82 kcal/mol) had significantly lower binding free energy compared to mangiferin-LasR (- 42.24 ± 3.94 kcal/mol) and the reference standard (azithromycin-LasR (- 40.01 ± 6.15 kcal/mol). ZINC D (95.16%) competed favorably with mangiferin (95.77%) as potential QS modulators at sub-minimum inhibitory concentrations relative to ZINC E (85.07%) and azithromycin (85.79%). These observations suggest mangiferin and related lead compounds as potential drug candidates for P. aeruginosa infection management.

Quorum Quenching of P. aeruginosa by Portulaca oleracea Methanolic Extract and Its Phytochemical Profile

Quorum sensing (QS) is a molecular communication mechanism among bacterial cells. It is critical in regulating virulence factors, motility, antibiotic resistance, and biofilm formation. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen linked to healthcare-associated infections, food poisoning, and biofilm formation. Treating infections caused by pathogenic bacteria has become a challenge due to the development of multi-antibiotic resistance upon continuous exposure of bacteria to antibiotics. An alternative strategy to conventional antimicrobials to decrease the bacterial pathogenicity is QS inhibition, also known as quorum quenching. Using plant-derived compounds is an environmentally friendly strategy to block the bacterial QS and inhibit bacterial growth. Portulaca oleracea is a popular plant in different countries and is also used in traditional medicine. It is widely consumed raw in salads and as garnishes, though it can be cooked as a vegetarian dish. This study evaluates the antimicrobial activity of the methanolic extract of P. oleracea and its effectiveness in blocking or attenuating the QS of P. aeruginosa. The agar well diffusion method used for screening the antibacterial activity showed a significant growth inhibition of P. aeruginosa by the extract at 500 mg/mL with a minimum inhibitory concentration of 31.25 mg/mL. A bioindicator bacterium, Chromobacterium violaceum CV026, was used to determine the effect of the methanolic extract on the QS of P. aeruginosa. The results indicated a significant reduction in biofilm formation, pyocyanin production, and LasA staphylolytic activity. The phytochemical analysis by Gas Chromatography-Mass Spectrometry showed that the methanolic extract contained several phenols, alkaloids, esters, and other compounds previously reported to have antibacterial and antioxidant effects. These findings highlight the effectiveness of P. oleracea methanolic extract in attenuating the QS and virulence factors of P. aeruginosa. This study suggests that P. oleracea is an important source of natural antimicrobials and its use would be beneficial in food and pharmaceutical applications.

Menadione as Antibiotic Adjuvant Against P. aeruginosa: Mechanism of Action, Efficacy and Safety

Background/Objectives: Antibiotic resistance in chronic lung infections caused by Pseudomonas aeruginosa requires alternative approaches to improve antibiotic efficacy. One promising approach is the use of adjuvant compounds that complement antibiotic therapy. This study explores the potential of menadione as an adjuvant to azithromycin against planktonic cells and biofilms of P. aeruginosa, focusing on its mechanisms of action and cytotoxicity in pulmonary cell models. Methods: The effect of menadione in improving the antibacterial and antibiofilm potency of azithromycin was tested against P. aeruginosa. Mechanistic studies in P. aeruginosa and AZMr-E. coli DH5α were performed to probe reactive oxygen species (ROS) production and bacterial membrane disruption. Cytotoxicity of antibacterial concentrations of menadione was assessed by measuring ROS levels and membrane integrity in Calu-3 and A549 lung epithelial cells. Results: Adding 0.5 µg/mL menadione to azithromycin reduced the minimum inhibitory concentration (MIC) by four-fold and the minimum biofilm eradication concentration (MBEC) by two-fold against P. aeruginosa. Adjuvant mechanisms of menadione involved ROS production and disruption of bacterial membranes. Cytotoxicity tests revealed that antibacterial concentrations of menadione (≤64 µg/mL) did not affect ROS levels or membrane integrity in lung cell lines. Conclusions: Menadione enhanced the efficacy of azithromycin against P. aeruginosa while exhibiting a favorable safety profile in lung epithelial cells at antibacterial concentrations. These findings suggest that menadione is a promising antibiotic adjuvant. However, as relevant data on the toxicity of menadione is sparse, further toxicity studies are required to ensure its safe use in complementing antibiotic therapy.

Biofilm battle: New transformative tactics to tackle the bacterial biofilm infections

Bacterial biofilm infections are the root cause of persistent infections and the prevalence of resistance to specific or multiple antibiotics. Biofilms have unique features that provide a protective environment for bacteria under various stress conditions and contribute significantly to the pathogenesis of chronic infections. They cover bacterial cells with a self-produced extracellular polymeric matrix, effectively hiding the bacterial cells and their targets. Conventional therapies cannot effectively treat and control bacterial biofilm infections. Therefore, advanced therapeutic means like microneedles, targeted tissue therapy, phage therapy, nanodrug therapy, combination drug therapy, microbial therapy, and immune cell hijacking therapy are needed to tackle the complex issue. These advanced therapies have shown promising results not only in bacterial biofilm infections but also in diseases such as cancer and genetic disorders. Due to their unique features and mechanisms, they significantly contribute to preventing bacterial infections by disrupting biofilm. This article aims to serve as a comprehensive overview of the ongoing battle against biofilms with transformative therapies. This article compiles advancements in new therapies that have demonstrated effective roles in the disruption of bacterial biofilms. We also discuss the current developments and Food and Drug Administration-approved status of these therapies. Additionally, this article summarizes the limitations and future steps needed for these therapies in the field of bacterial biofilm prevention. Thus, these therapies represent the future of preventing bacterial biofilm infections and could be also effective in the reversal of resistance.

Biofilm and Antibiotic Resistance Study of Bacteria Involved in Nosocomial Infections

Nosocomial infections are increasingly problematic due to growing bacterial resistance. Biofilms play a key role in the persistence of these infections, leading to treatment failures and poor patient outcomes. Addressing antibiotic resistance within biofilms is especially critical in hospitals, making it essential to develop new strategies to manage biofilm-related infections and curb bacterial resistance. The study, conducted at the regional hospital center in Agadir, Morocco, analyzed 75 bacteria (37 antibiotic-sensitive and 38 resistant). Seven bacteria were isolated from catheters, and others from preserved samples. Biofilm formation was assessed using the tissue culture plate (TCP) method, involving strain recovery; culture on cystine, lactose, electrolyte-deficient (CLED) medium; microplate inoculation; staining with crystal violet; and optical density (OD) measurement. The results showed that 77.33% of the bacteria formed biofilms. All catheter-isolated bacteria showed biofilm formation. Strong biofilm production was observed in 66.67% of Acinetobacter baumannii and in most Pseudomonas aeruginosa strains. Enterobacteriaceae also demonstrated significant biofilm formation. Notably, 70% of carbapenem-resistant bacteria showed strong biofilm production. Most nosocomial bacteria form biofilms, with a higher prevalence in antibiotic-resistant strains. Sensitive bacteria also form biofilms but less frequently. Bacterial conjugation may facilitate the acquisition of carbapenem resistance within biofilms.

Multifaceted Antipathogenic Activity of Two Novel Natural Products, Chermesiterpenoid B and Chermesiterpenoid B Seco Acid Methyl Ester, Against Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that causes both acute and chronic infections due to its virulence factors, biofilm formation and the ability to suppress the host immune system. Quorum sensing (QS) plays a key role in regulating these pathogenic traits and also downregulates the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) in host cells. In this study, we isolated two novel natural products from the jellyfish-derived fungus Penicillium chermesinum, chermesiterpenoid B (Che B) seco acid methyl ester (Che B ester) and Che B. Both compounds act as partial agonists of PPAR-γ and exhibit anti-QS activity. Che B ester and Che B were found to inhibit biofilm formation, reduce the production of proteases and decrease the infectivity of P. aeruginosa, all without affecting bacterial growth. In host cells, Che B ester and Che B reduced P. aeruginosa-induced inflammation by activating PPAR-γ. This multifaceted function makes these compounds promising candidates for developing new antipathogenic agents against bacterial infections with few side effects.

Effect of Candida albicans' supernatant on biofilm formation and virulence factors of Pseudomonas aeruginosa through las/rhl System

Pseudomonas aeruginosa (P. aeruginosa) and Candida albicans (C. albicans) are opportunistic pathogens whose mixed infections can exacerbate microbial dissemination and drug resistance, contributing to high mortality and morbidity rates among infected individuals. Few studies have explored the impact of C. albicans supernatant on P. aeruginosa, and the underlying mechanisms of such mixed infections remain unclear. In this study, we investigated the effects of C. albicans supernatant on biofilm formation and virulence factor activity in wild-type P. aeruginosa PAO1 and its quorum sensing-deficient mutants, ΔlasIrhlI and ΔlasRrhlR. Our results demonstrated that the biofilm formation capability and virulence were significantly higher in the PAO1 group compared to the ΔlasIrhlI and ΔlasRrhlR groups. Furthermore, exposure to C. albicans supernatant significantly enhanced both the biofilm formation and virulence of PAO1, whereas no significant changes were observed in the ΔlasIrhlI and ΔlasRrhlR mutants relative to their respective controls. These findings suggest that C. albicans supernatant may modulate P. aeruginosa biofilm formation and virulence via the las/rhl quorum sensing system.

Resilience and charge-dependent fibrillation of functional amyloid: Interactions of Pseudomonas biofilm-associated FapB and FapC amyloids

FapC and FapB are biofilm-associated amyloids involved in the virulence of Pseudomonas and other bacteria. We herein demonstrate their exceptional thermal and chemical resilience, suggesting that their biofilm structures might withstand standard sterilization, thereby contributing to the persistence of Pseudomonas aeruginosa infections. Our findings also underscore the impact of environmental factors on functional amyloid in Pseudomonas (Fap) proteins, suggesting that orthologs in different Pseudomonas strains adapt to specific environments and roles. Challenging previous assumptions about a simple nucleation role for FapB in promoting FapC aggregation, the study shows a significant influence of FapC on FapB aggregation. The interaction between these FapB and FapC is intricate: FapB stabilizes FapC fibrils, while FapC slows down FapB fibrillation but can still serve as a cross-seeding template. This complex interplay is the key to understanding their roles in bacterial biofilms. Furthermore, the study highlights distinct differences between Fap and Escherichia coli's CsgA (curli) amyloid, where CsgB assumes a simple unidirectional role in nucleating CsgA fibrillation, emphasizing the importance of a comprehensive understanding of various amyloid systems. This knowledge is vital for developing effective intervention strategies against bacterial infections and leveraging the unique properties of these amyloids in technological applications such as novel bionanomaterials or protective coatings.

Extended-spectrum β-lactamase-producing bacteria from hospital wastewater pipes: isolation, characterization and biofilm control using common disinfectants

BACKGROUND

Hospital wastewater systems have been identified as reservoirs for antibiotic-resistant bacteria, with biofilms harbouring extended-spectrum β-lactamase (ESBL)-producing micro-organisms posing significant infection risk.

AIM

To study the antimicrobial susceptibility and biofilm control of ESBL-producing bacteria from wastewater pipes from a tertiary care teaching hospital in Ireland, which had experienced endemic infection outbreaks caused by ESBL-producing bacteria.

METHODS

Following isolation of ESBL producers on selective agar, antibiotic susceptibility profiles were determined for a number of antibiotics assessed for their ability to form biofilms. Biofilm eradication studies using the commercially available disinfectants bleach, Optizan™, Virkon™ and Clinell™ were performed on selected isolates.

FINDINGS

ESBL-producing bacteria (N = 39 isolates) showed a high degree of resistance to β-lactams. Biofilm-forming ability ranged from non-adherent to strongly adherent and appeared to be source dependent, suggesting that the characteristics of the pipe environment played an important role in biofilm formation. All disinfectants showed effective biofilm eradication under suggested working conditions. Effectiveness was significantly reduced following reductions in concentration and contact time, with only Clinell™ showing significant biofilm reduction against all isolates at all concentrations and contact times tested. Of the chlorine-based formulations, Optizan™ frequently outperformed bleach at lower concentrations and treatment times. Biofilm eradication was strain dependent, with varying disinfectant response profiles observed from biofilms from different Stenotrophomonas maltophilia isolates.

CONCLUSIONS

This study highlights the high degree of ESBL-producing bacteria recovery from patient-facing hospital wastewater apparatus. Their ability to form resident biofilms and act as potential reservoirs of infection emphasizes the need for rigorous and effective infection control practices.

Applying a polysaccharide lyase from Stenotrophomonas maltophilia to disrupt alginate exopolysaccharide produced by Pseudomonas aeruginosa clinical isolates

Pseudomonas aeruginosa is considered one of the most challenging, drug-resistant, opportunistic pathogens partly due to its ability to synthesize robust biofilms. Biofilm is a mixture of extracellular polymeric substances (EPS) that encapsulates microbial cells, leading to immune evasion, antibiotic resistance, and thus higher risk of infection. In the cystic fibrosis lung environment, P. aeruginosa undergoes a mucoid transition, defined by overproduction of the exopolysaccharide alginate. Alginate encapsulation results in bacterial resistance to antibiotics and the host immune system. Given its role in airway inflammation and chronic infection, alginate is an obvious target to improve treatment for P. aeruginosa infection. Previously, we demonstrated polysaccharide lyase Smlt1473 from Stenotrophomonas maltophilia strain k279a can catalyze the degradation of multiple polyuronides in vitro, including D-mannuronic acid (poly-ManA). Poly-ManA is a major constituent of P. aeruginosa alginate, suggesting that Smlt1473 could have potential application against multidrug-resistant P. aeruginosa and perhaps other microbes with related biofilm composition. In this study, we demonstrate that Smlt1473 can inhibit and degrade alginate from P. aeruginosa. Additionally, we show that tested P. aeruginosa strains are dominant in acetylated alginate and that all but one have similar M-to-G ratios. These results indicate that variation in enzyme efficacy among the isolates is not primarily due to differences in total EPS or alginate chemical composition. Overall, these results demonstrate Smlt1473 can inhibit and degrade P. aeruginosa alginate and suggest that other factors including rate of EPS production, alginate sequence/chain length, or non-EPS components may explain differences in enzyme efficacy.

IMPORTANCE

Pseudomonas aeruginosa is a major opportunistic human pathogen in part due to its ability to synthesize biofilms that confer antibiotic resistance. Biofilm is a mixture of polysaccharides, DNA, and proteins that encapsulate cells, protecting them from antibiotics, disinfectants, and other cleaning agents. Due to its ability to increase antibiotic and immune resistance, the exopolysaccharide alginate plays a large role in airway inflammation and chronic P. aeruginosa infection. As a result, colonization with P. aeruginosa is the leading cause of morbidity and mortality in CF patients. Thus, it is an obvious target to improve the treatment regimen for P. aeruginosa infection. In this study, we demonstrate that polysaccharide lyase, Smlt1473, inhibits alginate secretion and degrades established alginate from a variety of mucoid P. aeruginosa clinical isolates. Additionally, Smlt1473 differs from other alginate lyases in that it is active against acetylated alginate, which is secreted during chronic lung infection. These results suggest that Smlt1473 may be useful in treating infections associated with alginate-producing P. aeruginosa, as well as have the potential to reduce P. aeruginosa EPS in non-clinical settings.

Epidemiological and molecular characteristics of extraintestinal pathogenic escherichia coli isolated from diseased cattle and sheep in Xinjiang, China from 2015 to 2019

Escherichia coli has become a common causative agent of infections in animals, inflicting serious economic losses on livestock production and posing a threat to public health. Escherichia coli infection is common and tends to be complex in Xinjiang, a major region of cattle and sheep breeding in China. This study aims to explore the current status and molecular characteristics of Escherichia coli infection in cattle and sheep in Xinjiang, as part of the disease prevention and control strategy. Herein we isolated Extraintestinal pathogenic Escherichia coli (ExPEC) from the liver, spleen, lung, heart, and lymph nodes of infected cattle and sheep (Xinjiang, China), and phylogenetic grouping, serotyping, and multilocus sequence typing were performed to determine epidemic and molecular characteristics. We also assessed their biofilm formation ability. A total of 132 strains of ExPEC were identified from diseased cattle and sheep, belonging to 7 phylogenetic groups. A and B1 are advantageous groups. Further, 22 serogroups were found, with O101 (26/132), O154 (14/132), and O65 (8/132) being the predominant ones. Among the seven sequence types identified by multilocus sequence typing, ST10 was the most common, followed by ST23 and ST457. Of 132, 105 (79.5%) strains were able to form biofilms: 15 strains (11.4%) were strong, 28 (21.2%) were medium, and 62 (47%) were weak biofilm producers. These findings will contribute to a better understanding of the molecular epidemiology of ExPEC in Xinjiang, China, and can be applied to the development, prevention, and disease control of future diagnostic tools and vaccine.

The Effect of Temperature over the Growth and Biofilm Formation of the Thermotolerant Aspergillus flavus

Aspergillus flavus is a medically relevant fungus, particularly in tropical regions. Although its aflatoxin production and thermotolerance are well documented, its biofilm-forming ability has received less attention, despite being a key factor in the virulence of A. flavus as an opportunistic pathogen, which can significantly impact therapeutic outcomes. To investigate the influence of temperature on the growth and biofilm formation of an A. flavus isolate, we compared it on solid media with the reference strain A. flavus ATCC 22546 and documented morphological changes during conidial germination. We examined biofilm formation in both strains across different temperatures and evaluated the susceptibility of this A. flavus isolate to antifungal agents in both planktonic and biofilm form. Our results showed that the temperature can promote conidiation on solid media. Radial growth was highest at 28 °C, while the conidial count and density were favored at higher temperatures. Moreover, we determined that 37 °C was the optimal temperature for conidial germination and biofilm formation. We described four distinct phases in A. flavus biofilm development-initiation (0-12 h), consolidation (12-24 h), maturation (24-48 h), and dispersion (48-72 h)-with the notable presence of conidial heads at 42 °C. Carbohydrates and proteins constitute the primary components of the extracellular matrix. We observed an abundance of lipid droplets within the hyphae of the MMe18 strain biofilm. The mature biofilms demonstrated reduced susceptibility to amphotericin B and itraconazole, requiring higher inhibitory concentrations for both antifungals compared with their planktonic counterparts.

From Cure to Crisis: Understanding the Evolution of Antibiotic-Resistant Bacteria in Human Microbiota

The growing prevalence of antibiotic-resistant bacteria within the human microbiome has become a pressing global health crisis. While antibiotics have revolutionized medicine by significantly reducing mortality and enabling advanced medical interventions, their misuse and overuse have led to the emergence of resistant bacterial strains. Key resistance mechanisms include genetic mutations, horizontal gene transfer, and biofilm formation, with the human microbiota acting as a reservoir for antibiotic resistance genes (ARGs). Industrialization and environmental factors have exacerbated this issue, contributing to a rise in infections with multidrug-resistant (MDR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Enterobacteriaceae. These resistant pathogens compromise the effectiveness of essential treatments like surgical prophylaxis and chemotherapy, increase healthcare costs, and prolong hospital stays. This crisis highlights the need for a global One-Health approach, particularly in regions with weak regulatory frameworks. Innovative strategies, including next-generation sequencing (NGS) technologies, offer promising avenues for mitigating resistance. Addressing this challenge requires coordinated efforts, encompassing research, policymaking, public education, and antibiotic stewardship, to safeguard current antibiotics and foster the development of new therapeutic solutions. An integrated, multidimensional strategy is essential to tackle this escalating problem and ensure the sustainability of effective antimicrobial treatments.

Multidrug-resistant bacteria quorum-sensing inhibitors: A particular focus on Pseudomonasaeruginosa

Many widely used conventional antibiotics have failed to show clinical efficacy against Pseudomonas aeruginosa (P. aeruginosa) due to the strain's rising resistance to most clinically relevant antimicrobials. P. aeruginosa uses quorum sensing to regulate its virulence and biofilm development, which contributes to its pathogenicity and drug resistance. This mechanism is responsible for the resurgence and persistence of infections. Therefore, targeting the virulence and pathogenicity of P. aeruginosa through quorum sensing (QS) is regarded as a potential target for anti-infective therapy. However, a number of natural and synthetic compounds have been demonstrated to interfere with quorum sensing, resulting in potential antibacterial agents. In this review, we discuss the mechanisms of P. aeruginosa QS and recent advances in the development of quorum sensing inhibitors (both synthetic and natural) that have the potential to become effective antibiotics.

Whole-Genome Sequencing of Resistance, Virulence and Regulation Genes in Extremely Resistant Strains of Pseudomonas aeruginosa

BACKGROUND/OBJECTIVES

Pseudomonas aeruginosa is a clinically significant opportunistic pathogen, renowned for its ability to acquire and develop diverse mechanisms of antibiotic resistance. This study examines the resistance, virulence, and regulatory mechanisms in extensively drug-resistant clinical strains of P. aeruginosa.

METHODS

Antibiotic susceptibility was assessed using the Minimum Inhibitory Concentration (MIC) method, and whole-genome sequencing (WGS) was performed on the Illumina NovaSeq platform.

RESULTS

The analysis demonstrated a higher prevalence of virulence genes compared to resistance and regulatory genes. Key virulence factors identified included secretion systems, motility, adhesion, and biofilm formation. Resistance mechanisms observed comprised efflux pumps and beta-lactamases, while regulatory systems involved two-component systems, transcriptional regulators, and sigma factors. Additionally, phenotypic profiles were found to correlate with resistance genes identified through genotypic analysis.

CONCLUSIONS

This study underscores the significant resistance and virulence of the clinical P. aeruginosa strains analyzed, highlighting the urgent need for alternative strategies to address infections caused by extensively drug-resistant bacteria.

Biochemistry of Bacterial Biofilm: Insights into Antibiotic Resistance Mechanisms and Therapeutic Intervention

Biofilms, composed of structured communities of bacteria embedded in a self-produced extracellular matrix, pose a significant challenge due to their heightened resistance to antibiotics and immune responses. This review highlights the mechanisms underpinning antibiotic resistance within bacterial biofilms, elucidating the adaptive strategies employed by microorganisms to withstand conventional antimicrobial agents. This encompasses the role of the extracellular matrix, altered gene expression, and the formation of persister cells, contributing to the recalcitrance of biofilms to eradication. A comprehensive understanding of these resistance mechanisms provides a for exploring innovative therapeutic interventions. This study explores promising avenues for future research, emphasizing the necessity of uncovering the specific genetic and phenotypic adaptations occurring within biofilms. The identification of vulnerabilities in biofilm architecture and the elucidation of key biofilm-specific targets emerge as crucial focal points for the development of targeted therapeutic strategies. In addressing the limitations of traditional antibiotics, this review discusses innovative therapeutic approaches. Nanomaterials with inherent antimicrobial properties, quorum-sensing inhibitors disrupting bacterial communication, and bacteriophages as biofilm-specific viral agents are highlighted as potential alternatives. The exploration of combination therapies, involving antimicrobial agents, biofilm-disrupting enzymes, and immunomodulators, is emphasized to enhance the efficacy of existing treatments and overcome biofilm resilience.

Encapsulation of Hydrogen Peroxide in PVA/PVP Hydrogels for Medical Applications

Researchers have been investigating the physical and morphological properties of biodegradable polymer and copolymer films, blending them with other chemicals to solve challenges in medical, industrial, and eco-environmental fields. The present study introduces a novel, straightforward method for preparing biodegradable hydrogels based on polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) for medical applications. The resulting PVA/PVP-based hydrogel uniquely combines the water absorbency, biocompatibility, and biodegradability of the polymer composite. For hygiene products and medical uses, such as wound healing, hydrogen peroxide (HP) was encapsulated in the PVA/PVP hydrogels for controlled release application. Incorporating PVP into PVA significantly enhances the hydrogel water absorbency and improves the mechanical properties. However, to mitigate the disadvantage of high water absorbency which could result in undesired early dissolution, efforts were made to increase the water resistance and the mechanical characteristics of these hydrogels using freeze-thaw (F/T) cycles and chemical crosslinking PVA chains with trisodium trimetaphosphate (STMP). The resulting hydrogels serve as environmentally friendly bio-based polymer blends, broadening their applications in medical and industrial products. The structural and morphological properties of the hydrogel were characterized using Fourier transform infrared spectroscopy (FTIR), environmental scanning electron microscope analysis (E-SEM), and water-swelling tests. The HP controlled release rate was evaluated through kinetic release experiments using the ex vivo skin model. The antibacterial activity of the hydrogel films was examined on four medically relevant bacteria: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, with an adapted disk diffusion assay. Using this assay, we also evaluated the antibacterial effect of the hydrogel films over the course of days, demonstrating the HP controlled release from these hydrogels. These findings support further in vivo investigation into controlled HP release systems for improved wound-healing outcomes.

Bacterial infections associated with cutaneous leishmaniasis in Salah Al-Din province, Iraq

Bacterial co-infection with cutaneous leishmaniasis (CL) can effect on the clinical appearance of lesions and delay the healing process. The pattern of bacterial pathogens involved has rarely been investigated in Iraq. The aim of present study was to identify the bacterial agents contaminating CL and their susceptibility to commonly used antibiotics. Four hundred cases of CL were diagnosed in Salah El-Din General Hospital, Iraq. A total of 424 ulcer samples obtained from 400 patients of CL were cultured, and all isolates were diagnosed based on phenotypic characteristics of colonies, bacterial cells and using biochemical tests. No bacterial growth appeared in 124 cases (29.25 %) of the total number of examined ulcer samples, whereas 300 cases (70.75 %) were contaminated. Both Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes) and Gram-negative bacterial species (Escherichi coli, Klebsiella spp., Pseudomonas aeruginosa) were present. The infection with S. aureus represented the highest percentage (26.42 %), while Ps. aeruginosa had the lowest percentage (2.83 %) compared with other bacterial infections. The sensitivity of the isolated bacteria associated with CL was tested against a number of antibiotics (Amoxicillin, Ampicillin, Cefixime, Chloramphenlcol, Doxycycline, Tetracycline). Resistance to Amoxicillin, Ampicillin, and Cefixime was generally high. While, Chloramphenicol showed absolute effectiveness against isolated bacteria. The results of the current study show that bacterial infections should be considered in diagnosing and treating CL lesions, with Chloramphenicol demonstrating the highest efficiency in treating such bacterial infections. The present study also suggests that hygiene, use of suitable disinfectants, controlling of antibiotic administration and prescription in hospitals and pharmacies must be ensured. In addition, regular surveillance in the endemic area will help control bacterial co-infection and hamper the occurrence of drug-resistant pathogens. The lesion care and management of secondary bacterial infection are essential and anti -leishmanial therapy in CL may be more effective when combined with antibiotics. Future molecular studies are needed to identify the species of Leishmania causing CL in Iraq to gain a better understanding of their clinical manifestations (dry or moist ulcers) and their associated bacteria.

ZnO-Rutin nanostructure as a potent antibiofilm agent against Pseudomonasaeruginosa

Pseudomonas aeruginosa is a common human pathogen that is resistant to multiple antibiotics due to its ability to form biofilms. Developing novel nanoformulations capable of inhibiting and removing biofilms offers a promising solution for controlling biofilm-related infections. In this study, we investigated the anti-biofilm activity of rutin-conjugated ZnO nanoparticles (ZnO-Rutin NPs) in pathogenic strains of P. aeruginosa. The synthesized ZnO-Rutin NPs had amorphous shapes with sizes ranging from 14 to 100 nm. The broth microdilution assay revealed that ZnO-Rutin NPs, with an MIC value of 2 mg/mL, exhibit greater antimicrobial activity than ZnO NPs and rutin alone. Based on crystal violet staining, the biofilm inhibition rate by ½ MIC of the conjugated nanoparticles was recorded at above 90 %. The significant reduction in exopolysaccharide (62.75-66.37 %) and alginate (38.3-57.61 %) levels, as well as the formation of thin biofilms in the ZnO-Rutin NP-treated group, confirmed the anti-biofilm potential of these nanoparticles. Additionally, a significant decrease in the metabolic activity and viable cells of mature biofilms was observed after exposure to the conjugated nanoparticles. Furthermore, ZnO-Rutin NPs considerably attenuated the expression of the Las-Rhl quorum-sensing transcriptional regulator genes (lasR and rhlR) in P. aeruginosa by 0.39-0.40 and 0.25-0.42 folds, respectively. This work demonstrated that ZnO-Rutin NPs are remarkably capable of inhibiting the initial stage of biofilm formation and eradicating mature biofilms, suggesting they could be a useful agent for treating P. aeruginosa biofilm-related infections.

Transcytosable and Ultrasound-Activated Liposome Enables Deep Penetration of Biofilm for Surgical Site Infection Management

Biofilm-associated surgical site infection (BSSI) is a common and grievous postoperative complication lacking effective remedies, mainly due to the poor drug accumulation and penetration in the biofilms featured by dense extracellular polymeric substances (EPSs). Here, it is found that the vascular cell adhesion molecule-1 (VCAM1) is highly overexpressed in the vascular cells of BSSI. It is proposed that the combination of VCAM1-mediated transcytosis and ultrasonic cavitation can consecutively overcome the biological barriers of vascular endothelial cells and EPS for biofilm eradication. To demonstrate the feasibility, a VCAM1-targeted and ultrasound (US)-activated liposome (LPCOTML) loaded with a reactive-oxygen-species (ROS)-responsive lipoid prodrug of oleoyl meropenem, sonosensitizer of lipoid Ce6, and perfluoropentane is developed. LPCOTML can recognize the receptors on vascular cells, and initiate receptor-mediated transcytosis for transendothelial transport into the BSSI periphery. LPCOTML subsequently transforms from nanoparticle into microbubble via liquid-gas phase transition under US irradiation, triggering strong ultrasonic cavitation to blow up the EPS and deeply penetrate the biofilms. The sonosensitizer Ce6 induces ROS production under US irradiation and triggers the release of meropenem to induce potent antibacterial effect in a BSSI model. This study presents an effective strategy to tackle the biological barriers in BSSI via combining receptor-mediated transcytosis and ultrasonic cavitation.

Nanocarrier-Mediated Dermal Drug Delivery System of Antimicrobial Agents for Targeting Skin and Soft Tissue Infections

Antimicrobial resistance in disease-causing microbes is seen as a severe problem that affects the entire world, makes therapy less effective, and raises mortality rates. Dermal antimicrobial therapy becomes a desirable choice in the management of infectious disorders since the rising resistance to systemic antimicrobial treatment frequently necessitates the use of more toxic drugs. Nanoparticulate systems such as nanobactericides, which have built-in antibacterial activity, and nanocarriers, which function as drug delivery systems for conventional antimicrobials, are just two examples of the treatment methods made feasible by nanotechnology. Silver nanoparticles, zinc oxide nanoparticles, and titanium dioxide nanoparticles are examples of inorganic nanoparticles that are efficient on sensitive and multidrug-resistant bacterial strains both as nanobactericides and nanocarriers. To stop the growth of microorganisms that are resistant to standard antimicrobials, various antimicrobials for dermal application are widely used. This review covers the most prevalent microbes responsible for skin and soft tissue infections, techniques to deliver dermal antimicrobials, topical antimicrobial safety concerns, current issues, challenges, and potential future developments. A thorough and methodical search of databases, such as Google Scholar, PubMed, Science Direct, and others, using specified keyword combinations, such as "antimicrobials," "dermal," "nanocarriers," and numerous others, was used to gather relevant literature for this work.

Can distinct Gram-negative biofilm-forming bacteria have different impacts on ciprofloxacin lung penetration?

Literature have shown that Gram-negative bacteria release endotoxins which alter drug membrane transporters and could potentially influence antimicrobials distribution to the infection site depending on the infecting bacteria. Previously, a population pharmacokinetic (popPK) model describing ciprofloxacin (CIP) concentrations in healthy, and Pseudomonas aeruginosa pneumonic rats showed that the chronic stage of the infection significantly reduced the drug lung penetration. In this study, CIP lung penetration in Klebsiella pneumoniae chronically (14 d) infected rats following CIP 20 mg/kg i.v. bolus dosing was investigated and the popPK model developed previously was used to evaluate CIP lung exposure. Drug plasma exposure was similar for both bacteria and higher than observed in healthy animals. Probability of target attainment analysis using plasma data following current dosing regimen (20 mg q8h equivalent to 400 mg q8h in humans) showed that CIP PK/PD index (ƒAUC0-24/MIC ≥90) is achieved for the most prevalent MIC's of both bacteria. However, CIP free lung concentrations were reduced in infected animals by 46.8 % (P. aeruginosa) and 68.4 % (K. pneumoniae) in comparison to healthy animals. The higher lung clearance observed (0.306 L/h/kg) in K. pneumoniae infected animals lead to a lower free CIP lung exposure in comparison to the P. aeruginosa group (0.105 L/h/kg). In summary, although plasma PK/PD index is achieved by the current regimen, chronic pneumonia by biofilm-forming bacteria decreases lung exposure to CIP and this decrease is dependent on the infecting bacteria. The clinical relevance of this finding needs to be determined.

Inhibition of Clinical Multidrug-Resistant Pseudomonas aeruginosa Biofilms by Cinnamaldehyde and Eugenol From Essential Oils: In Vitro and In Silico Analysis

Pseudomonas aeruginosa causes nosocomial infections and chronic diseases. Cinnamomum cassia and Syzygium aromaticum are used natural antimicrobials. Essential oil (EO) from C. cassia (CCEO) and S. aromaticum (CEO) was characterized using GC-MS analysis. Eugenol (82.31%), eugenol acetate (10.57%), and β-caryophyllene (3.41%) were major constituents in CEO while cinnamaldehyde (88.18%), cinnamyl acetate (2.85%) and 2-methoxy cinnamaldehyde (1.77%) were main components in CCEO. The EOs and major constituents exhibited good antimicrobial activity against clinical strains of P. aeruginosa. Cinnamaldehyde exhibited the best antimicrobial effect with minimal inhibitory concentration (MIC) as low as 0.031% ± 0.07% (v/v) and inhibition zones reaching 30 ± 0.5 mm diameter. Test samples showed antibiofilm activities against two culture types and seven clinical strains of P. aeruginosa at concentrations of 2MIC to MIC/4. CCEO and its major constituent cinnamaldehyde were more active, compared to CEO and its major constituent eugenol. Scanning electron microscopy images showed untreated colonies with well-developed biofilms while there was significant reduction of biofilms with distorted architecture and cell shrinkage upon treatment with test samples. In silico studies indicated great interactions between the major compounds, eugenol and cinnamaldehyde, with the receptor proteins of P. aeruginosa revealed by negative binding energies. Eugenol and cinnamaldehyde exhibited appreciable druglikeness.

Antimicrobial resistance profile, biofilm forming capacity and associated factors of multidrug resistance in Pseudomonas aeruginosa among patients admitted at Tikur Anbessa Specialized Hospital and Yekatit 12 Hospital Medical College in Addis Ababa, Ethiopia

BACKGROUND

Pseudomonas aeruginosa is one of the leading causes of nosocomial infections and the most common multidrug-resistant pathogen. This study aimed to determine antimicrobial resistance patterns, biofilm-forming capacity, and associated factors of multidrug resistance in P. aeruginosa isolates at two hospitals in Addis Ababa, Ethiopia.

METHODS

A cross-sectional study was conducted from August 2022 to August 2023 at Tikur Anbessa Specialized Hospital and Yekatit 12 Hospital Medical College. Culture and identification of P. aeruginosa were done using standard microbiological methods. An antimicrobial susceptibility test was done by Kirby-Bauer disk diffusion according to CLSI recommendations. The microtiter plate assay method was used to determine biofilm-forming capacity. SPSS version 25 was used for data analysis. Bivariate and multivariable logistic regression were used to assess factors associated with multidrug resistance in P. aeruginosa. The Spearman correlation coefficient (rs = 0.266)) was performed to evaluate the relationship between biofilm formation and drug resistance.

RESULTS

The overall prevalence of P. aeruginosa was 19.6%. High levels of resistance were observed for ciprofloxacin (51.8%), ceftazidime (50.6%), and cefepime (48.2%). The level of multidrug-resistance was 56.6%. The isolates showed better susceptibility to ceftazidime-avibactam (95.2%) and imipenem (79.5%). Overall, 95.2% of P. aeruginosa were biofilm-producing isolates, and 27.7% and 39.8% of isolates were strong and moderate biofilm producers, respectively. A positive correlation and statistically significant relationship was observed between resistance to multiple drugs and the level of biofilm formation (rs = 0.266; p-value = 0.015). Previous history of exposure to ciprofloxacin (OR, 5.1; CI, 1.12-24.7, p-value, 0.032) was identified as an independent associated factor for multidrug resistance in P. aeruginosa.

CONCLUSION

The present study indicates an association between multidrug resistance in P. aeruginosa and its biofilm formation capabilities. Additionally, over half of the isolates were resistant to multiple drugs, with prior use of ciprofloxacin linked to the development of multidrug-resistance. These findings suggest that antibiotic stewardship programs in hospital settings may be beneficial in addressing resistance.

Impaired Biofilm Development on Graphene Oxide-Metal Nanoparticle Composites

Purpose

Biofilms are one of the main threats related to bacteria. Owing to their complex structure, in which bacteria are embedded in the extracellular matrix, they are extremely challenging to eradicate, especially since they can inhabit both biotic and abiotic surfaces. This study aimed to create an effective antibiofilm nanofilm based on graphene oxide-metal nanoparticles (GOM-NPs).

Methods

To create nanofilms, physicochemical analysis was performed, including zeta potential (Zp) (and the nanocomposites stability in time) and size distribution measurements, scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), and atomic force microscopy (AFM) of the nanofilm surfaces. During biological analysis, reactive oxygen species (ROS) and antioxidant capacity were measured in planktonic cells treated with the nanocomposites. Thereafter, biofilm formation was checked via crystal violet staining, biofilm thickness was assessed by confocal microscopy using double fluorescent staining, and biofilm structure was analyzed by scanning electron microscopy.

Results

The results showed that two of the three nanocomposites were effective in reducing biofilm formation (GOAg and GOZnO), although the nanofilms were characterized by the roughest surface, indicating that high surface roughness is unfavorable for biofilm formation by the tested bacterial species (Staphylococcus aureus (ATCC 25923), Salmonella enterica (ATCC 13076), Pseudomonas aeruginosa (ATCC 27853)).

Conclusion

The performed analysis indicated that graphene oxide may be a platform for metal nanoparticles that enhances their properties (eg colloidal stability, which is maintained over time). Nanocomposites based on graphene oxide with silver nanoparticles and other types of nanocomposites with zinc oxide were effective against biofilms, contributing to changes throughout the biofilm structure, causing a significant reduction in the thickness of the structure, and affecting cell distribution. A nanocomposite consisting of graphene oxide with copper nanoparticles inhibited the biofilm, but to a lesser extent.

Mitigating Health Risks Through Environmental Tracking of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a prevalent nosocomial pathogen and a significant reservoir of antimicrobial resistance genes in residential and built environments. It is also widespread in various indoor and outdoor settings, including sewage, surface waters, soil, recreational waters (both treated and untreated), and industrial effluents. Surveillance efforts for P. aeruginosa are primarily focused on hospitals rather than built environments. However, evidence links multidrug-resistant P. aeruginosa of human origin with activity in built environments and hospital settings. Consequently, tracking this pathogen across all environments is crucial for understanding the mechanisms of reverse transmission from built environments to humans. This review explores public health hygiene by examining the prevalence of P. aeruginosa in various environments, its sequence types, the factors contributing to multidrug resistance, and the identification methods through global surveillance. Whole-genome sequencing with sequence typing and real-time quantitative PCR are widely used to identify and study antimicrobial-resistant strains worldwide. Additionally, advanced techniques such as functional metagenomics, next-generation sequencing, MALDI-TOF, and biosensors are being extensively employed to detect antimicrobial-resistant strains and mitigate the ongoing evolution of bacterial resistance to antibiotics. Our review strongly underscores the importance of environmental monitoring of P. aeruginosa in preventing human infections. Furthermore, strategic planning in built environments is essential for effective epidemiological surveillance of P. aeruginosa and the development of comprehensive risk assessment models.