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The central nervous system coordinates peripheral cellular stress responses, including the unfolded protein response of the mitochondria (UPRMT); however, the contexts for which this regulatory capability evolved are unknown. UPRMT is up-regulated upon pathogenic infection and in metabolic flux, and the olfactory nervous system has been shown to regulate pathogen resistance and peripheral metabolic activity. Therefore, we asked whether the olfactory nervous system in Caenorhabditis elegans controls the UPRMT cell nonautonomously. We found that silencing a single inhibitory olfactory neuron pair, AWC, led to robust induction of UPRMT and reduction of oxidative phosphorylation dependent on serotonin signaling and parkin-mediated mitophagy. Further, AWC ablation confers resistance to the pathogenic bacteria Pseudomonas aeruginosa partially dependent on the UPRMT transcription factor atfs-1 and fully dependent on mitophagy machinery. These data illustrate a role for the olfactory nervous system in regulating whole-organism mitochondrial dynamics, perhaps in preparation for postprandial metabolic stress or pathogenic infection.

Microbial biofilms represent an important lifestyle for bacteria and are dynamic three-dimensional structures. Cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous signaling molecule that is known to be tightly regulated with biofilm processes. While measurements of global levels of c-di-GMP have proven valuable toward understanding the genetic control of c-di-GMP production, there is a need for tools to observe the local changes of c-di-GMP production in biofilm processes. We have developed a label-free method for the direct detection of c-di-GMP in microbial colony biofilms using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). We applied this method to the enteric pathogen Vibrio cholerae, the marine symbiont V. fischeri, and the opportunistic pathogen Pseudomonas aeruginosa PA14 and detected spatial and temporal changes in c-di-GMP signal that accompanied genetic alterations in factors that synthesize and degrade the compound. We further demonstrated how this method can be simultaneously applied to detect additional metabolites of interest from a single sample.

Left ventricular assist devices (LVAD) are increasingly used for management of heart failure; infection remains a frequent complication. Phage therapy has been successful in a variety of antibiotic refractory infections and is of interest in treating LVAD infections. We performed a retrospective review of four patients that underwent five separate courses of intravenous (IV) phage therapy with concomitant antibiotic for treatment of endovascular Pseudomonas aeruginosa LVAD infection. We assessed phage susceptibility, bacterial strain sequencing, serum neutralization, biofilm activity, and shelf-life of phage preparations. Five treatments of one to four wild-type virulent phage(s) were administered for 14-51 days after informed consent and regulatory approval. There was no successful outcome. Breakthrough bacteremia occurred in four of five treatments. Two patients died from the underlying infection. We noted a variable decline in phage susceptibility following three of five treatments, four of four tested developed serum neutralization, and prophage presence was confirmed in isolates of two tested patients. Two phage preparations showed an initial titer drop. Phage biofilm activity was confirmed in two. Phage susceptibility alone was not predictive of clinical efficacy in P. aeruginosa endovascular LVAD infection. IV phage was associated with serum neutralization in most cases though lack of clinical effect may be multifactorial including presence of multiple bacterial isolates with varying phage susceptibility, presence of prophages, decline in phage titers, and possible lack of biofilm activity. Breakthrough bacteremia occurred frequently (while the organism remained susceptible to administered phage) and is an important safety consideration.

Comprehensive Summary: Redox nanozymes offer an appealing reactive oxygen species (ROS)‐based antibacterial strategy via disrupting intracellular homeostasis, however, they still face many obstacles such as low enzymic activity and irreversible loss of catalytic active center. Meanwhile, the antioxidant glutathione (GSH) overexpressed in infected sites would limit the therapy efficiency. Herein, we develop a multifunctional nanozyme based on copper(I) (Cu+) ion doped MoO3–x (Cu+‐MoO3–x) by a simple yet efficient oxygen vacancy‐reduced strategy without any pretreatment or additional agents. The resultant Cu+‐MoO3–x hybrid possesses enhanced peroxidase‐like (POD‐like) activity, rapid GSH‐depleting function and biodegradable ability. It can achieve highly efficient elimination of Pseudomonas aeruginosa (P. aeruginosa) via disrupting cellular redox balance. More intriguingly, GSH‐depleting redox reaction between Cu+‐MoO3–x and GSH could translate Mo6+ into Mo5+, thereby leading to partial recovery of POD‐like activity of Cu+‐MoO3–x hybrid for continuous ∙OH generation. In vitro and in vivo experiments demonstrated that Cu+‐MoO3–x hybrid had stronger antibacterial property compared to MoO3–x by rapid GSH consumption and plentiful ∙OH generation without providing extra H2O2, as well as neglective toxicity to healthy organs. In view of its remarkable enzymic activity and good biosafety, the developed Cu+‐MoO3–x redox nanozyme can be used as a promising antimicrobial for P. aeruginosa infection. [ABSTRACT FROM AUTHOR]

The emerging field of green synthesis within nanobiotechnology presents significant environmental and economic advantages compared to conventional methodologies. This study investigates the synthesis and application of chitosan nanoparticles (ChNPs) using Cassia fistula (CF) leaf extract as a sustainable, and bio-based approach. Characterization of CF-ChNPs confirmed effective bioconversion and also demonstrated significant antimicrobial activity. Notably, CF-ChNPs demonstrated a remarkable antimicrobial effect against Pseudomonas aeruginosa, with a zone of inhibition of 17 ± 0.2 mm surpassing the impact on other organisms tested. The CF-ChNPs exhibited an initial burst release of 28 ± 0.28% after 2 h, gradually achieving a controlled release of 76.3 ± 0.43% within 24 h. In addition, CF-ChNPs exhibited an antioxidant activity of 43.1 ± 0.48% and showed excellent antibiofilm activity against Staphylococcus aureus in comparison to other organisms. The cell viability assay results have confirmed that CF-ChNPs do not have any negative impact on the viability of L929 fibroblasts, further highlighting their potential as versatile nanomaterials for treating microbial infections and other therapeutic applications. [ABSTRACT FROM AUTHOR]

Background. The primary pathogen responsible for bronchoscope contamination is Pseudomonas aeruginosa. Conventional techniques for bronchoscopy disinfection and pathogen identification methods are characterized by time‐consuming and operation complexly. The objective of this research is to establish a prompt and precise method for the identification of Pseudomonas aeruginosa, with the ultimate goal of mitigating the risk of nosocomial infections linked to this pathogen. Methods. The magnetic nanoparticles (MNPs) were synthesized in a single step, followed by the optimization of the coating process with antibodies and invertase to produce the bifunctionalized IMIc. Monoclonal antibodies were immobilized on microplates for the specific capture and enrichment of Pseudomonas aeruginosa. Upon the presence of Pseudomonas aeruginosa, the monoclonal antibodies, the test sample, and the IMIc formed sandwich structures. The subsequent addition of a sucrose solution allowed for the detection of glucose produced through invertase hydrolysis by a personal glucose meter, enabling quantitative assessment of Pseudomonas aeruginosa concentration. Results. TEM image demonstrates that the MNPs exhibit a consistent spherical shape. NTA determined that the grain diameter of magnetic nanoparticles was 200 nm. FTIR spectrum revealed the successful modification of two carboxyl groups on the MNPs. The optimization of the incubation pH of the microplate‐coated antibody was 7. The optimization of the incubation time of the microplate‐coated antibody was 2 h. The optimization of the ligation pH for the polyclonal antibody was 5. Reaction times of polyclonal antibodies linked to magnetic beads was 1 h. The pH of invertase linked by magnetic beads was 4. Conclusion. This article presents a novel qualitative and quantitative immunoassay for point‐of‐care monitoring of P. aeruginosa utilizing PGM as a readout. The PGM represents a convenient and accurate quantitative detection method suitable for potential clinical diagnostic applications. [ABSTRACT FROM AUTHOR]

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

Background: The 2016 IDSA guideline recommends a treatment duration of at least 7 days for hospital-acquired (HAP)/ventilator-associated pneumonia (VAP). The limited literature has demonstrated higher rates of recurrence for non-glucose fermenting gram-negative bacilli with short course therapy, raising the concern of optimal treatment duration for these pathogens. Therefore, we aimed to compare the outcomes for patients receiving shorter therapy treatment (≤ 8 days) versus longer regimen (> 8 days) for the treatment of multidrug resistant (MDR) Pseudomonas pneumonia. Methods: A single-center, retrospective cohort study was conducted to evaluate adult patients receiving an antimicrobial regimen with activity against MDR Pseudomonas aeruginosa in respiratory culture between 2017 and 2020 for a minimum of 6 consecutive days. Exclusion criteria were inmates, those with polymicrobial pneumonia, community-acquired pneumonia, and infections requiring prolonged antibiotic therapy. Results: Of 427 patients with MDR P. aeruginosa respiratory isolates, 85 patients were included. Baseline characteristics were similar among groups with a median age of 65.5 years and median APACHE 2 score of 20. Roughly 75% had ventilator-associated pneumonia. Compared to those who received ≤ 8 days of therapy, no difference was seen for clinical success in patients treated for more than 8 days (80% vs. 65.5%, p = 0.16). The number of 30-day and 90-day in-hospital mortality, 30-days relapse, and other secondary outcomes did not significantly differ among the treatment groups. Conclusions: Prolonging treatment duration beyond 8 days did not improve patient outcomes for MDR P. aeruginosa HAP/VAP. [ABSTRACT FROM AUTHOR]

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

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

Introduction Bloodstream infections are a significant threat to soldiers wounded in combat and contribute to preventable deaths. Novel and combination therapies that can be delivered on the battlefield or in lower roles of care are urgently needed to address the threat of bloodstream infection among military personnel. In this manuscript, we tested the antibacterial capability of silver ions (Ag+), with long-appreciated antibacterial properties, against ESKAPEE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species, and Escherichia coli) pathogens. Materials and Methods We used the GENESYS (RAIN LLC) device to deliver Ag+ to Gram-positive and Gram-negative ESKAPEE organisms grown in broth, human blood, and serum. Following the Ag+ treatment, we quantified the antibacterial effects by quantifying colony-forming units. Results We found that Ag+ was bactericidal against 5 Gram-negative organisms, K pneumoniae, A baumannii, P aeruginosa , E cloacae , and E coli , and bacteriostatic against 2 Gram-positive organisms, E faecium and S aureus. The whole blood and serum inhibited the bactericidal activity of Ag+ against a common agent of bloodstream infection, P aeruginosa. Finally, when Ag+ was added in conjunction with antibiotic in the presence of whole blood, there was no significant effect of Ag+ over antibiotic alone. Conclusions Our results confirmed that Ag+ has broad-spectrum antibacterial properties. However, the therapeutic value of Ag+ may not extend to the treatment of bloodstream infections because of the inhibition of Ag+ activity in blood and serum. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to create resorbable nanoparticles (NPs) using poly(lactic-co-glycolic acid) (PLGA) to develop novel antibacterial therapeutics for the treatment of chronic wound infections that are susceptible to recurrent infections. By first performing a release study, it was possible to predict the behavior of the different PLGA NP formulations and assess the efficacy of the nanocomposite drug delivery system. These PLGA NP formulations consisted of varying ratios of PLGA without polyvinyl alcohol (PVA) and PLGA with PVA (PLGA-PVA) (i.e. 25:75[PLGA25], 50:50[PLGA50], and 75:25[PLGA75]). Then, different antibiotics (i.e. ciprofloxacin and gentamicin) were incorporated into the PLGA NP formulations to test the antibacterial efficacy of these antimicrobial NPs against different pathogens (i.e. methicillin-resistant Staphylococcus aureus USA300 [MRSA], Pseudomonas aeruginosa FRD1, and Acinetobacter baumannii BAA1605). Of particular interest was testing against the MRSA strain USA300 and the P. aeruginosa strain FRD1. This was possible by measuring the zone of inhibition. A 3-day period was used to monitor the antibacterial efficacy of the different PLGA NP formulations (i.e. PLGA25, PLGA50, and a 1:1 combination of PLGA25:PLGA50) against A. baumannii BAA1605 , MRSA, and P aeruginosa FRD1. Throughout the study, A. baumannii was a negative control and was resistant to all the PLGA NP formulations loaded with ciprofloxacin and gentamicin. At the end of the 3-day period, the PLGA and PLGA50 ciprofloxacin-loaded formulations produced zones of inhibition of 27 mm and 23 mm, respectively, against P. aeruginosa FRD1. This indicated that P. aeruginosa FRD1 was susceptible to both formulations. The mixed formulations with equal parts PLGA25:PLGA50 loaded with ciprofloxacin produced a zone of inhibition (i.e. 25 mm). This again indicated that P. aeruginosa FRD1 was susceptible to ciprofloxacin. The formulations tested against MRSA showed that only gentamicin-loaded formulations produced intermediate results, and that ciprofloxacin-loaded formulations were ineffective. The PLGA25 and the PLGA50 NP formulations loaded with gentamicin both produced zones of inhibition of 13 mm. This indicated that MRSA was intermediate to both the formulations. The PLGA25:PLGA50 loaded with gentamicin produced a zone of inhibition of 14 mm, which again showed that MRSA was intermediate to this formulation. Overall, these PLGA NP formulations showed the sustained antibacterial potential of a burst release, followed by a sustained release of antibiotics from antibiotics loaded PLGA NPs in a controlled manner. In the future, this can help prevent the emergence of recurrent infections in the treatment of chronic wounds and reduce the number of medical dressing changes. [ABSTRACT FROM AUTHOR]

Medicinal plants provide a significant supply of natural compounds that can be used to develop new therapeutic medicines for treating severe illnesses including microbial infections. The genus Bambusa, which belongs to the Poaceae family, encompasses a vast and widely distributed collection of plants that possess a wide range of traditional uses in the treatment of various diseases. This study examined the ethanolic extracts of Bambusa tulda, along with its fractions such as ethyl acetate, petroleum ether, n-butanol, and water, to investigate their qualitative and quantitative phytochemical, antioxidant, and antibacterial properties. FTIR analysis of ethanolic powdered shoot extracts shows, presence of different functional groups including C-H, C-O, O-H and aromatic groups by showing stretching’s in different wavelengths. The extracts underwent testing to evaluate their antimicrobial activity against various strains of bacteria by using agar disc diffusion method and micro-dilution techniques to determine the minimum inhibitory and bactericidal concentrations. Additionally, the antioxidant activity of the extracts was assessed using the scavenging activity of DPPH radical methods. The extracts exhibited a robust positive connection between their antioxidant activity and the combined amounts of phenolics and flavonoids. The IC50 values of n-butanol, ethanol, water, petroleum ether, and ethyl acetate fraction show in ascending order 10.77+0.24 μg/ml, 11.35+0.13 μg/ml, 13.36+0.11 μg/ml,13.93+0.71 μg/ml and14.25+ 0.27 μg/ml respectively. The extracts have been shown effective efficacy against Escherichia coli and Staphylococcus aureus bacteria. However, it did not show any responses against Klebsiella pneumoniae and Pseudomonas aeruginosa. Escherichia coli exhibited greater susceptibility to the extracts compared to S. aureus, with the n-butanol fraction being the most potent extract. [ABSTRACT FROM AUTHOR]

Background: Pseudomonas aeruginosa is a key pathogen in cystic fibrosis (CF) associated infections, known for its biofilm-forming ability and resistance to multiple antibiotics. Understanding the relationship between biofilm production and antibiotic resistance profiles in clinical isolates can guide treatment strategies. Aims and Objectives: The aims of this study were to investigate the biofilm-forming abilities and antibiotic resistance profiles of clinical P. aeruginosa isolates from patients with CF and to determine the relationship between these two factors and their impact on treatment efficacy. Materials and Methods: A cross-sectional study was conducted on 100 clinical isolates of P. aeruginosa from CF patients. Biofilmforming capacity was categorized as strong, moderate, or weak based on quantitative assays. Antibiotic resistance was assessed for ciprofloxacin, tobramycin, ceftazidime, meropenem, and piperacillin/tazobactam. Multi-drug resistance was defined as resistance to three or more antibiotic classes. Statistical correlations between biofilm-forming capacity and resistance levels were evaluated using the Chi-square tests. Results: Fifty-six percentages of isolates were strong biofilm producers, while 34% and 10% were moderate and weak producers, respectively. The highest antibiotic resistance was observed against ciprofloxacin (60%), followed by tobramycin (50%) and ceftazidime (45%). Forty percentages of the isolates were classified as multi-drug resistant. Strong biofilm producers demonstrated a significantly high correlation with antibiotic resistance (P<0.05). Two predominant clonal groups were identified among the isolates, suggesting a possible clonal spread of resistance traits. Conclusion: The study confirms a strong association between robust biofilm production and heightened antibiotic resistance in P. aeruginosa isolates from CF patients. These findings highlight the need for targeted therapeutic strategies to disrupt biofilm formation and curb resistance spread. [ABSTRACT FROM AUTHOR]

Emerging resistance of Gram-negative bacteria, including Pseudomonas aeruginosa, to commonly used detergents and disinfectant is encountering us with hazard. Inappropriate use of disinfectants has forced bacteria to gain resistance. The ability of bacteria to extrude substrates from the cellular interior to the external environment has enabled them to persist in exposure to toxic compounds, which is due to existence of transport proteins. Efflux pumps, in Gram-negative bacteria, are proteins responsible for exporting molecules outside of the cell, by crossing the two membranes. In this study, 40 P. aeruginosa strains from hospitals, clinics, and burn center laundries and 40 P. aeruginosa strains from urban laundries were collected. This study evaluated the minimum inhibitory concentration (MIC) level of sodium dodecyl sulfate (SDS), didecyldimethylammonium chloride (DDAC), and octenidine dihydrochloride (Od) in P. aeruginosa strains. The real-time PCR was carried out to evaluate the expression of MexAB-OprM, MexCD-OprJ, and MexXY-OprM efflux system. The obtained results indicated a higher MIC level for SDS, DDAC, and Od in medical laundries. The sub-MIC level of DDAC and Od increased the expression level of MexAB-OprM, MexCD-OprJ, and MexXY-OprM in P. aeruginosa strains, suggesting that efflux pumps contribute to disinfectant resistance in P. aeruginosa. [ABSTRACT FROM AUTHOR]

Background Bacterial RNA polymerase (RNAP) is a promising target for antimicrobial chemotherapy due to its indispensable role in bacterial growth and survival. Among its components, only the rpoB gene encoding the β-subunit is known for its association with rifampicin resistance. We recently identified a variant of the RNAP α-subunit (RpoA) in Pseudomonas aeruginosa, conferring heightened bacterial susceptibility to antimicrobials. This susceptibility was attributed to the specific down-regulation of the MexEF-OprN efflux pump. Objectives We asked how to distinguish antimicrobial-susceptible variant strains from clinical isolates. Methods In this study, we identified various P. aeruginosa RpoA variants from clinical sources. Using the sequence alignment of different bacterial RpoA species, we computed the positional conservation of substitutions in RpoA variants using Shannon Entropy. Results Our findings revealed that selective RpoA variant strains exhibited distinct profiles of antimicrobial susceptibility. Notably, RpoA variant strains, containing single-substitutions in the C-terminal domain (α-CTD) but not the N-terminal domain (α-NTD), showed attenuated MexEF-OprN expression and increased susceptibility to MexEF-OprN-specific antibiotics. Furthermore, we observed a close correlation between the susceptibility of these α-CTD RpoA variant strains to antibiotics and the conservation degrees of positional substitutions. Conclusions Our findings demonstrate the prevalence of antimicrobial-susceptible RpoA variant strains among P. aeruginosa clinical isolates. The identified positional conservation pattern in our study facilitates the rapid classification of RpoA variant strains with distinct drug resistances. Given the high conservation of RNAP across bacterial species, our findings open a new therapeutic perspective for precisely and efficiently combating pathogenic RpoA variant strains with specific antimicrobials. [ABSTRACT FROM AUTHOR]

Objectives The measurement of VOCs release in the headspace of a bacterial culture represents a new approach to rapidly assess antimicrobial susceptibility. Herein, we evaluated the diagnostic performance of the VITEK® REVEAL™ system directly from a collection of Gram-negative positive blood cultures. Materials and methods One hundred and twenty-eight positive blood cultures were included in the analysis (Enterobacterales, n  = 95; Pseudomonas aeruginosa , n  = 21; Acinetobacter baumannii complex, n  = 12). Samples were processed using VITEK® REVEAL™ according to the manufacturer's recommendations, and MICs of 22 antimicrobials were compared with those obtained using reference methods. Categorical agreement (CA), essential agreement (EA) and categorical errors were calculated. Results Overall, 2220 strain/antibiotic pair combinations were analysed. Of these, most were classified as resistant by reference antimicrobial susceptibility testing (1091/2220; 48.7%). The overall CA and EA were 97.6% and 97.7%, respectively. CA ranged from 97.5% in Enterobacterales to 97.9% in both P. aeruginosa and A. baumannii complex. The overall number of categorical discrepancies were: 18 very major errors (1.6%), 13 major errors (1.2%) and 22 minor errors (2.4%). EA ranged from 95.2% in P. aeruginosa to 98.1% in Enterobacterales. Screening test for ESBL phenotype was positive, indeterminate and negative in 13.7%, 32.6% and 27.4% of Enterobacterales isolates tested by both VITEK® REVEAL™ and the reference method, showing 100% CA. Conclusions VITEK® REVEAL™ represents a reliable tool to obtain antimicrobial susceptibility results of the main Gram-negative species directly from positive blood cultures with time to results of less than 8 h. [ABSTRACT FROM AUTHOR]

Background β-lactam antibiotics, which inhibit penicillin-binding protein 3 (PBP3) that is required for cell division, play a key role in treating P. aeruginosa infections. Some sequence variations in PBP3 have been associated with β-lactam resistance but the effects of variations on antibiotic susceptibility and on cell division have not been quantified. Antibiotic efflux can also reduce susceptibility. Objectives To quantify the effects of PBP3 variations on β-lactam susceptibility and cell morphology in P. aeruginosa. Methods Nineteen PBP3 variants were expressed from a plasmid in the reference strain P. aeruginosa PAO1 and genome engineering was used to construct five mutants expressing PBP3 variants from the chromosome. The effects of the variations on β-lactam minimum inhibitory concentration (MIC) and cell morphology were measured. Results Some PBP3 variations reduced susceptibility to a variety of β-lactam antibiotics including meropenem, ceftazidime, cefepime and ticarcillin with different variations affecting different antibiotics. None of the tested variations reduced susceptibility to imipenem or piperacillin. Antibiotic susceptibility was further reduced when PBP3 variants were expressed in mutant bacteria overexpressing the MexAB-OprM efflux pump, with some variations conferring clinical levels of resistance. Some PBP3 variations, and sub-MIC levels of β-lactams, reduced bacterial growth rates and inhibited cell division, causing elongated cells. Conclusions PBP3 variations in P. aeruginosa can increase the MIC of multiple β-lactam antibiotics, although not imipenem or piperacillin. PBP3 variations, or the presence of sub-lethal levels of β-lactams, result in elongated cells indicating that variations reduce the activity of PBP3 and may reduce bacterial fitness. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa infection causes pneumonia and sepsis. Previous research found that X‐ray radiation can induce P. aeruginosa to release outer membrane vesicles (OMVs) of relatively consistent sizes. This study found that OMVs derived from X‐ray‐irradiated P. aeruginosa can significantly inhibit lung leakage, inflammatory cell infiltrating into lung, and the production of pro‐inflammatory cytokines, IL‐1β and TNFα caused by P. aeruginosa infection under preventive and therapeutic administration conditions. Under the same conditions, OMVs also significantly alleviated pathological characteristics of lung injury, including pulmonary edema, pulmonary hemorrhage, and alveolar wall thickening. OMVs also significantly reduced bacterial burdens in peritoneal cavity, accompanied by a reduction in the number of viable bacteria capable of forming bacterial colonies. Pretreating macrophages and neutrophils with OMVs enhances their bactericidal ability. When bacteria were cocultured with treated cells, the number of viable bacteria capable of forming bacterial colonies was significantly reduced. OMVs themselves have not been shown to cause any lung injury or affect bacterial viability. Therefore, OMVs derived from X‐ray‐irradiated P. aeruginosa may not only be applied in prevention and treatment of diseases associated with P. aeruginosa infection, but also served as an excellent vaccine development platform. [ABSTRACT FROM AUTHOR]

The urgency of multidrug-resistant (MDR) bacterial infections in wounds is a significant concern due to the high prevalence of MDR in healthcare settings. Black pigmented marine bacteria, strain PS1C, were isolated from marine sediment on Awur Beach Jepara, Central Java, Indonesia, and cultured in the laboratory. The aim of this research includes molecular identification of strain PS1C, extracting black pigment from strain PS1C, isolation of MDR bacteria from wounds, and evaluating the antibacterial activity of black pigment from strain PS1C against MDR bacteria isolates of wound infections. We examined the 16S rRNA gene sequences strain PS1C to identify the species. Then, the black pigment from PS1C was extracted using methanol: acetone (7:3) solvent. Antibacterial activity was evaluated against MDR bacteria from wounds with the microdilution method. A black-pigmented bacterium was isolated and identified as Pseudomonas aeruginosa PS1C. We found that the black pigment from P. aeruginosa PS1C can be developed as an antibacterial agent against the MDR bacterial isolate of wounds with MIC and MBC values of 6.25-12.5 mg/ml and 6.25-25 mg/ml, respectively. In conclusion, the study's findings highlight the potential of the extract of black pigment from P. aeruginosa PS1C as an antibacterial agent against wound-causing MDR bacteria and reinforce previous research into P. aeruginosa can be isolated from marine sources. Additional in vivo investigations and the identification of the antibacterial activity's mode of action are required. [ABSTRACT FROM AUTHOR]

Purpose: Carbapenem resistant Pseudomonas aeruginosa (CR-PA) is escalating worldwide and leaves clinicians few therapeutic options in recent years, β-lactam/β-lactamase inhibitor combinations (ceftolozane-tazobactam, ceftazidime-avibactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of P. aeruginosa infection and have shown potent activity against isolates defined as carbapenem resistant. The aim of this study was to determine the phenotypic profile of these agents against CR-PA in the emerging setting of carbapenemases. Methods: CR-PA clinical isolates were collected from three teaching hospitals in different geographical regions between January 2017-December 2021. All isolates were subjected to phenotypic carbapenemase testing using modified carbapenem inactivation method. MICs were determined by reference broth microdilution and evaluated according to EUCAST standards, while genotypic profiling was determined using PCR methods. Results: 244 CR-PA sourced most frequently from the respiratory tract (32.2%), blood (20.4%) and urine (17.5%) were evaluated. Of all isolates, 32 (13.1%) were phenotypically and 38 (15.6%) were genotypically defined as carbapenemase-positive. The most common carbapenemase was GES (63.1%), followed by VIM (15.8%). The MIC50/90(S%) of ceftazidime/avibactam, ceftolozane/tazobactam and cefiderocol in all CR-PA isolates were 4 and 32 (80%), 1 and > 64 (69%) and 0.25 and 1 mg/L (96%), respectively. Cefiderocol was also the most active agent in carbapenemase-positive isolates (90%). Conslusion: While ceftolozane/tazobactam and ceftazidime/avibactam remained highly active against CR-PA devoid of carbapenemases, cefiderocol provided potent in vitro activity irrespective of carbapenemase production. When considering the potential clinical utility of newer agents against CR-PA, regional variations in carbapenemase prevalence must be considered. [ABSTRACT FROM AUTHOR]

This study compared the anti-pseudomonal effects between nephrite-impregnated contact lenses (CLs) and conventional and cosmetic CLs. After inoculation with Pseudomonas aeruginosa (P.aeruginosa), we counted the number of bacteria on the CL surface and observed each surface using atomic force microscopy (AFM) and scanning electron microscopy (SEM). To estimate potential harm of nephrite-impregnated CLs, we conducted a safety test using a rabbit model, treated with all CL types. Both conventional and cosmetic CLs (n = 258 ± 2.9 × 104, 368 ± 2.2 × 104) showed significantly decreased number of attached bacteria when compared with those without nephrite impregnation (n = 134 ± 0.8 × 104, 238 ± 2.5 × 104, p < 0.0001, respectively). AFM and SEM revealed that P. aeruginosa was less attached to the nephrite-impregnated CLs than to the conventional and cosmetic CLs, although those with nephrite impregnation had rougher surface. In the safety test, there were no significant differences in the findings between four groups, and the clarity and stability of all corneas were preserved. Nephrite may be used as a next-generation substance to reduce infectious keratitis caused by P. aeruginosa when added to CLs. [ABSTRACT FROM AUTHOR]

Development of multi-, extensively-, and pandrug-resistant (MDR, XDR, and PDR) strains of Pseudomonas aeruginosa remains a major problem in medical care. The present study evaluated the effect of antimicrobial photodynamic therapy (aPDT) as a monotherapy and in combination with colistin against P. aeruginosa isolates. Two P. aeruginosa isolates recovered from patients with respiratory tract infections were examined in this study. Minimum inhibitory concentration (MIC) of colistin was determined by the colistin broth disk elution (CBDE) and the reference broth microdilution (rBMD) methods. aPDT was performed using the photosensitizer (Ps) riboflavin at several concentrations and a light-emitting diode (LED) emitting blue light for different irradiation times with or without colistin at 1/2 × MIC concentration. Both PA1 and PA2 isolates were identified as colistin-resistant P. aeruginosa with a MIC ≥4 μg/mL by the CBDE and MICs of 512 μg/mL and 256 μg/mL, respectively, by the rBMD. In aPDT, neither riboflavin nor LED light alone had antibacterial effects. The values of colony forming units per milliliter (CFU/mL) in both isolates were significantly reduced by LED + Ps treatments in a time-dependent manner (LED irradiation time) and dose-dependent manner (Ps concentration). In comparison with control, treatment with Ps (50 μM) + LED (120 s) and Ps (100 μM) + LED (120 s) resulted in 0.27 log 10 CFU/mL and 0.43 log 10 CFU/mL reductions in PA1, and 0.28 log 10 CFU/mL and 0.34 log 10 CFU/mL reductions in PA2, respectively, (P < 0.01). The best results were obtained after the combination of aPDT followed by colistin, which increased bacterial reduction, resulting in a 0.41−0.7 log 10 CFU/mL reduction for PA1 and 0.35−0.83 log 10 CFU/mL reduction for PA2 (P = 0.001). This study suggests the potential implications of aPDT in combination with antibiotics, such as colistin for treatment of difficult-to-treat P. aeruginosa infections. [ABSTRACT FROM AUTHOR]

Microplastics in the aquatic environment are susceptible to colonization by surrounding microorganisms, which form biofilms over the microplastic's surface. These biofilm‐laden microplastics can then interact with a diverse array of contaminants. In the present study, biofilms were grown on microplastics in a laboratory setting using Pseudomonas aeruginosa as a model biofilm‐forming bacterium for periods of 5 to 15 days. The sorption of three organic compounds representing different levels of hydrophobicity, namely methylene blue (MB), phenanthrol, and phenanthrene, was used to evaluate the effect of biofilm biomass on the adsorption of organic contaminants to microplastics. The sorption of MB and phenanthrol was found to increase with biofouling time, indicating affinity between these contaminants and the biofilm biomass on the particle. However, the presence of a biofilm did not influence the sorption of phenanthrene on the microplastics. These results suggest that the hydrophobicity of organic contaminants plays a major role in how biofouling of microplastics will influence contaminant sorption by microplastics. For some contaminants, biofilm can enhance the role of microplastics as contaminant vectors. These findings emphasize the need to understand the biomass load on environmental microplastics and the contaminants that associate with it for an accurate representation of the risk associated with microplastics in the environment. Environ Toxicol Chem 2024;43:1973–1981. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen accountable for severe illness and mortality among immunocompromised individuals due to its extraordinary resistance to antibiotics. The regulation of pathogenic traits in P. aeruginosa is governed by a quorum sensing (QS) signaling molecule named acyl homoserine lactone (AHL). The present study investigated the inhibitory effects of the compound, Artocarpus heterophyllus Lam (A. heterophyllus), on the number of AHL-dependent components produced by P. aeruginosa (PAO1). A. heterophyllus is considered as a beneficial natural compound with notable inhibitory effects on several pathogens. The present study investigated the antimicrobial and antibiofilm activities of A. heterophyllus against PAO1 through in vitro experiments, including minimum inhibitory concentration tests, biofilm inhibition assays and growth curve analysis. The results demonstrated that the methanolic extract of A. heterophyllus at a concentration of 10 mg/ml effectively inhibited PAO1. Additionally, the extract exhibited a 55.12% biofilm inhibitory effect at the lowest sub-inhibitory concentration of 2.5 mg/ml, without affecting planktonic cell growth. On the whole, the findings of the present study indicate the prospective signifi- cance of A. heterophyllus as an anti-pathogenic agent, which is effective in reducing QS-dependent infection in PAO1. [ABSTRACT FROM AUTHOR]

Introduction and purpose: We report a case of extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) scleritis after pterygium surgery. Methods: Case report. Results: A 58-year-old farmer presented with a 40-day history of severe pain, swelling, and blurred vision after a pterygium excision was performed at another institute. The patient was on multiple medications with no relief. The examination showed a nasally located scleral thinning in his right eye, with ulceration and infiltrates. Microbiology revealed Pseudomonas aeruginosa, which showed intermediate sensitivity to colistin only. The patient was administered topical (0.19%) and intravenous colistin and dexamethasone. There was a rapid reduction in symptoms, and the lesions healed over the next 2 months. Conclusions: To the best of our knowledge, this is the first case report of XDR-PA scleritis. We suggest the possibility of evolving drug resistance caused by the iatrogenic use of antibiotics during the early stages of the disease course. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa PR23 isolated from the hydrocarbon contaminated soil can tolerate and degrade mixture of polyaromatic hydrocarbons (PAHs) at an initial concentration of 1300 ppm. The degradation and intermediates formed were assessed by gas chromatography-mass spectrometry (GC–MS) analysis. The isolated strain was able to degrade 59.2% of the mixture of PAHs in 3 days and 71.6% by day 15. Effect of PAHs on protein expression in Pseudomonas aeruginosa PR23 was studied using nano LC–MS/MS. Thirty-six proteins showed a more than 2-fold increase in expression in the presence of mixture of PAHs. Out of these proteins, 7 proteins have been reported for their role in degradation of naphthalene, phenanthrene, and pyrene. The data revealed the presence of 16 proteins that were uniquely expressed in the presence of mixture of PAHs. A twin-arginine translocation signal peptide (Tat system), known for the transportation of folded proteins across the cell membrane, showed more than 8-fold increased expression in the presence of mixture of PAHs. These results indicate that the isolated strain adopts the conditions in the presence of mixture of PAHs by modulating its metabolic and physiological processes. These findings suggest that Pseudomonas aeruginosa PR23 may be a suitable candidate for use in the development of strategies for bioremediation of mixtures of PAHs. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen that causes infectious diseases. It has high tendency to form biofilms, resulting in the failure of traditional antibiotic therapies. Inspired by the phenomenon that co-culture of Escherichia coli (E. coli) and P. aeruginosa leads to a biofilm reduction, we reveal that E. coli exopolysaccharides (EPS) can disrupt P. aeruginosa biofilm and increase its antibiotic susceptibility. The results show that E. coli EPS effectively inhibit biofilm formation and disrupt mature biofilms in P. aeruginosa, Staphylococcus aureus , and E. coli itself. The maximal inhibition and disruption rates against P. aeruginosa biofilm are 40 % and 47 %, respectively. Based on the biofilm-disrupting ability of E. coli EPS, we develop an E. coli EPS/antibiotic combining strategy for the treatment of P. aeruginosa biofilms. The combination with E. coli EPS increases the antibacterial efficiency of tobramycin against P. aeruginosa biofilms in vitro and in vivo. This study provides a promising strategy for treating biofilm infections. Biofilm formation is a leading cause of chronic infections. It blocks antibiotics, increases antibiotic-tolerance, and aids in immune evasion, thus representing a great challenge in clinic. This study proposes a promising approach to combat pathogenic Pseudomonas aeruginosa (P. aeruginosa) biofilms by combining Escherichia coli exopolysaccharides with antibiotics. This strategy shows high efficiency in different P. aeruginosa stains, including two laboratory strains, PAO1 and ATCC 10145, as well as a clinically acquired carbapenem-resistant strain. In addition, in vivo experiments have shown that this approach is effective against implanted P. aeruginosa biofilms and can prevent systemic inflammation in mice. This strategy offers new possibilities to address the clinical failure of conventional antibiotic therapies for microbial biofilms. [Display omitted] [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is a Gram-negative water-borne opportunistic pathogen. Reservoirs of bacteria can infect vulnerable populations. Mitigation of this risk in health care includes regular microbiology monitoring and chemical/thermal disinfection of outlets. Where contamination is persistent, point-of-use filters/antimicrobial showers may be used to reduce the bioburden. This study tested the efficacy of a silver nanoparticle (Ag+)-impregnated antimicrobial showerhead against P. aeruginosa under simulated conditions. Test (excised from Ag+-impregnated showerhead) and control (stainless steel) coupons (∼1 cm2; N =108) were inoculated with 10 μL [∼103 colony-forming units (CFU)] P. aeruginosa (NCTC 10662 and wild-types) and overlaid with coverslips. Coupons were incubated at ambient temperature (∼40% relative humidity) for 0 min, 30 min, 2 h, 4 h and 24 h. Coupons and coverslips were transferred to neutralizer solution, followed by bead washing for bacterial recovery and enumeration. Contamination ranged from ∼2.90 log 10 CFU (±0.14 log 10 ; type strain) to ∼3.02 log 10 CFU (±0.16 log 10 ; wild-types). No significant reductions in the P. aeruginosa bioburden were observed for any of the three strains (P >0.05). Analogous bacterial decline was noted between the test and control coupons (falling to below the detection limit) between 4 and 24 h, possibly due to desiccation. Whilst being an economically and environmentally friendly option, antimicrobial showers may not be appropriate to reduce the bioburden in healthcare waters. Previous research has demonstrated the bactericidal effects of Ag+; however, this was not established in the present study. Although the concentration of silver in the test materials was unknown, these findings suggest that antimicrobial showerheads may require higher concentrations of Ag+ to display antimicrobial activity. Further testing is required to determine efficacy against biofilms. [ABSTRACT FROM AUTHOR]

The global concern over health issues related to heavy metal pollution has driven the adoption of various treatment technologies. The investigation into optimal conditions for cadmium biosorption and bioaccumulation was conducted using a resilient bacterial strain, Pseudomonas aeruginosa DR7, which was isolated from ponds. The equilibrium time of the adsorption process of living cells was much longer than that of non‐living cells, which was about 240 min, which indicates that living cells have intracellular accumulation and delay the adsorption process. Living cells favored a pH of 6.0, while non‐living cells showed higher efficiency at pH 7.0, demonstrating the pH‐dependent nature of metal biosorption. In this context, the maximum biosorption capacities for cadmium using non‐living cells and living cells were 103.8 mg/g and 70.94 mg/g, under cell mass of 1.0 g/L, pH 7.0, initial metal concentration of 200 mg/L, and contact time of 240 min, respectively. Cadmium biosorption by living cells was more accurately described by the Freundlich isothermal model, whereas the Langmuir model was used for non‐living cells. Living cells tend to show pseudo‐second‐order kinetic adsorption behavior, while non‐living cells tend to show pseudo‐first‐order kinetic adsorption behavior. Fourier‐transform infrared spectroscopy (FTIR) analysis suggested that the hydroxyl, amino, and carboxyl groups all play a role in biosorption. Scanning electron microscopy (SEM)–energy dispersive x‐ray spectroscopy (EDS) showed that the high‐temperature treatment destroys the integrity of the cell wall, which enhances the permeability of the cell wall, thus increasing the biosorption of Cd (II) by the non‐living cells. The study found that P. aeruginosa DR7 with high temperature inactivation has a higher Cd(II) adsorption capacity than living cells, making it a green and environmentally friendly biological adsorbent for wastewater treatment with heavy metals. [ABSTRACT FROM AUTHOR]

17 β‐Estradiol is produced by animals, and humans and excreted through excreta, and has endocrine‐disrupting activity. Bacterial degradation is one of the suitable methods used for the removal of 17 β‐estradiol (E2) from the natural environment. In this study, E2‐degrading bacteria were screened from the enriched sediment sample from the wastewater environment. Two bacterial strains of E2‐degrading bacteria (Stenotrophomonas maltophilia MN08 and Pseudomonas aeruginosa KL10) were determined and >70% of E2‐degradation was achieved. The strain MN08 could rapidly remove approximately 86.5% ± 1.3% of E2 within 7 days of treatment. In addition, the strain KL10 removed 79.5% ± 1% of E2 within the same period. Optimized culture temperature and pH of the medium could improve E2‐degradation. The results demonstrated that the strain MN08 exhibited maximum E2‐degradation activity at 35°C, and pH 8.0. The optimal pH for strain KL10 to degrade E2 ranged from 7.0 to 9.0. The E2‐degradation level for the mixture culture systems can exhibit synergistic E2‐degradation activity. The degradation of the MN08 and KL10 individual strains was 87.3% ± 1.2% and 81.4% ± 1.5%, respectively. The E2‐degradation potential for the mixed culture system was 91.3% ± 2.9% under optimized conditions in which 100 mg/L of E2 served as the sole source of carbon and energy. The present finding demonstrates that the co‐culture of S. maltophilia MN08 and P. aeruginosa KL10 may provide a promising bio‐treatment strategy for the removal of steroids from wastewater. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) and polylactic acid (PLA) are among the polymers used in the food industry. In this study, crude extracts of Dunaliella salina were used to treat the surface of 3D printed materials studied, aiming to provide them with an anti-adhesive property against Pseudomonas aeruginosa. The hydrophobicity of treated and untreated surfaces was characterized using the contact angle method. Furthermore, the adhesive behavior of P. aeruginosa toward the substrata surfaces was also studied theoretically and experimentally. The results showed that the untreated PLA was hydrophobic, while the untreated PET was hydrophilic. It was also found that the treated materials became hydrophilic and electron-donating. The total energy of adhesion revealed that P. aeruginosa adhesion was theoretically favorable on untreated materials, while it was unfavorable on treated ones. Moreover, the experimental data proved that the adhesion to untreated substrata was obtained, while there was complete inhibition of adhesion to treated surfaces. [ABSTRACT FROM AUTHOR]

Understanding factors influencing Listeria monocytogenes biofilms aid in developing more effective elimination/prevention strategies. This study examined the effect of temperature (4 °C, 21 °C, 30 °C), materials (stainless steel 316 L with 2B and 2 R finishes, glass, and polypropylene), and slope (0°/horizontal or 90°/vertical) on mono- and dual-species biofilms using two L. monocytogenes strains and one Pseudomonas aeruginosa strain. All biofilms were grown in 10% TSB for 24 h and analyzed using culture-based methods. Additionally, the architecture of monospecies biofilms was studied using fluorescence microscopy. Overall, P. aeruginosa showed higher biofilm formation potential (6.2 log CFU/cm2) than L. monocytogenes (4.0 log CFU/cm2). Temperature greatly influenced P. aeruginosa and varied for L. monocytogenes. The slope predominantly influenced L. monocytogenes monospecies biofilms, with cell counts increasing by up to 2 log CFU/cm2. Surface material had little impact on biofilm formation. The study highlights the varying effects of different parameters on multispecies biofilms and the importance of surface geometry. HIGHLIGHTS: Surface material does not affect L. monocytogenes or P. aeruginosa biofilms L. monocytogenes produces more biofilm on horizontal surfaces than on vertical surfaces In dual-species biofilm, L. monocytogenes shows enhanced biofilm production Increased temperature often results in enhanced biofilm formation [ABSTRACT FROM AUTHOR]

Background: Carbapenem resistance in Pseudomonas aeruginosa is a serious global health problem. We investigated the clonal distribution and its association with the carbapenem resistance mechanisms of carbapenem-non-susceptible P. aeruginosa isolates from three Korean hospitals. Methods: A total of 155 carbapenem-non-susceptible P. aeruginosa isolates collected between 2011 and 2019 were analyzed for sequence types (STs), antimicrobial susceptibility, and carbapenem resistance mechanisms, including carbapenemase production, the presence of resistance genes, OprD mutations, and the hyperproduction of AmpC ß-lactamase. Results: Sixty STs were identified in carbapenem-non-susceptible P. aeruginosa isolates. Two high-risk clones, ST235 (N=41) and ST111 (N=20), were predominant; however, sporadic STs were more prevalent than high-risk clones. The resistance rate to amikacin was the lowest (49.7%), whereas that to piperacillin was the highest (92.3%). Of the 155 carbapenem-non-susceptible isolates, 43 (27.7%) produced carbapenemases. Three metallo-β-lactamase (MBL) genes, blaIMP-6 (N=38), blaVIM-2(N=3), and blaNDM-1(N=2), were detected. blaIMP-6 was detected in clonal complex 235 isolates. Two ST773 isolates carried blaNDM-1 and rmtB. Frameshift mutations in oprD were identified in all isolates tested, regardless of the presence of MBL genes. Hyperproduction of AmpC was detected in MBL gene-negative isolates. Conclusions: Frameshift mutations in oprD combined with MBL production or hyperproduction of AmpC are responsible for carbapenem resistance in P. aeruginosa. Further attention is required to curb the emergence and spread of new carbapenem-resistant P. aeruginosa clones. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa (PA) is a widely prevalent opportunistic pathogen. Multiple resistant strains of PA have emerged from excessive or inappropriate use of antibiotics, making their eradication increasingly difficult. Therefore, the search for highly efficient and secure novel antimicrobial agents is crucial. According to reports, there is an increasing exploration of nanometals for antibacterial purposes. The antibacterial mechanisms involving the nanomaterials themselves, the release of ions, and the induced oxidative stress causing leakage and damage to biomolecules are widely accepted. Additionally, the study of the cytotoxicity of metal nanoparticles is crucial for their antibacterial applications. This article summarizes the types of metal nanomaterials and metal oxide nanomaterials that can be used against PA, their respective unique antibacterial mechanisms, cytotoxicity, and efforts made to improve antibacterial performance and reduce toxicity, including combination therapy with other materials and antibiotics, as well as green synthesis approaches. [ABSTRACT FROM AUTHOR]

Background Objectives Materials and Methods Results Conclusions and Clinical Relevance Otitis externa (OE) is one of the most frequently diagnosed dermatological diseases in dogs, having a multifactorial aetiology. Among the bacterial agents associated with canine OE, Pseudomonas aeruginosa is of special concern owing to its frequent multidrug resistance profile and ability to form biofilms related to the infection's chronicity and recurrence.The main objective of this study was to evaluate and compare the antibiofilm activity of two innovative antimicrobials—an otological gel containing a synthetic antimicrobial peptide and Lavandula angustifolia essential oil—with gentamicin (a conventional antibiotic) using biofilm‐producing P. aeruginosa isolates obtained from dogs with OE.The biofilm eradication capacity of gentamicin, otological gel and lavender oil was determined against a collection of 12 P. aeruginosa biofilm‐producers among 35 clinical isolates obtained from the ear canals of dogs with OE. Also, the antimicrobial activity of the otological gel against P. aeruginosa biofilms was assessed in an in vitro model of dog cerumen.Lavender oil showed the best effectiveness after 30 min of contact, eradicating 58.3% (seven of 12) of the isolates, and gentamicin showed full eradication (12 of 12) after 24 h. The otological gel acted more slowly than the lavender oil; yet at 24 h, the antibiofilm capacity of both compounds was similar, with no significant difference between them. It also was found that triglycerides from synthetic cerumen earwax had antipseudomonal activity and, when combined with the otological gel, led to the full eradication of P. aeruginosa.The results of this in vitro study indicate that lavender oil and the otological gel may be effective topical treatments for canine OE promoted by P. aeruginosa biofilm‐producers, as alternatives to gentamicin. [ABSTRACT FROM AUTHOR]

AbstractBackgroundMethodsResultsConclusionCombination therapy is an attractive therapeutic option for extensively drug-resistant (XDR) Pseudomonas aeruginosa infections. Existing data support the combination of aztreonam and ceftazidime/avibactam (CZA) against class serine-β-lactamase (SBL)- and metallo-β-lactamase (MBL) - producing Enterobacterales. However, data about that combination against SBL- and MBL-producing P. aeruginosa are scarce. The objective of the study was to assess the in vitro activity of CZA and aztreonam alone and in combination against SBL- and MBL-producing XDR P. aeruginosa isolatesThe combination was analyzed by means of the hollow-fiber infection model in three selected carbapenemase-producing P. aeruginosa isolates that were representative of the three most common XDRP. aeruginosa high-risk clones (ST175, ST111, ST235) responsible for global nosocomial infection outbreaks.The three isolates were nonsusceptible to CZA and nonsusceptible to aztreonam. In the dynamic hollow-fiber infection model, the combination of CZA plus aztreonam exerts a bactericidal effect on the isolates, regardless of their resistance mechanism and demonstrates synergistic interactions against three isolates, achieving a bacterial reduction of 5.07 log10 CFU/ml, 5.2 log10 CFU/ml and 4 log10 CFU/ml, respectively.The combination of CZA and aztreonam significantly enhanced the in vitro efficacy against XDR P. aeruginosa isolates compared to each monotherapy. This improvement suggests that the combination could serve as a feasible treatment alternative for infections caused by carbapenemase-producing XDR P. aeruginosa, especially in scenarios where no other treatment options are available. [ABSTRACT FROM AUTHOR]

Purpose: To describe the prevalence and antibiotic resistance profiles of Pseudomonasaeruginosa isolated from the Asia Cornea Society Infectious Keratitis Study (ACSIKS). Methods: All bacterial isolates from ACSIKS underwent repeat microbiological identification in a central repository in Singapore. Minimum inhibitory concentration (MIC) determination was conducted for isolates of P. aeruginosa against thirteen antibiotics from 6 different classes, and categorized based on Clinical Laboratory Standard Institutes' reference ranges. The percentage rates of resistance (non-susceptibility) to each antibiotic included isolates of both intermediate and complete resistance. Multi-drug resistance (MDR) was defined as non-susceptibility to at least one agent in three or more antimicrobial classes. Results: Of the 1493 unique bacterial specimens obtained from ACSIKS, 319 isolates were of P. aeruginosa. The majority of isolates were from centers in India (n = 118, 37%), Singapore (n = 90, 28.2%), Hong Kong (n = 31, 9.7%) and Thailand (n = 30, 9.4%). The cumulative antibiotic resistance rate was the greatest for polymyxin B (100%), ciprofloxacin (17.6%) and moxifloxacin (16.9%), and lowest for cefepime (11.6%) and amikacin (13.5%). Isolates from India demonstrated the highest antibiotic resistance rates of all the centers, and included moxifloxacin (47.5%) and ciprofloxacin (39.8%). Forty-eight of the 59 MDR isolates also originated from India. Antibiotic resistance rates were significantly lower in the other ACSIKS centers, and were typically less than 10%. Conclusions: The antibiotic resistance profiles of P. aeruginosa varied between different countries. While it was low for most countries, substantial antibiotic resistance and a significant number of multi-drug resistant isolates were noted in the centers from India. [ABSTRACT FROM AUTHOR]

Metabolism provides the foundation for all cellular functions. During persistent infections, in adapted pathogenic bacteria metabolism functions radically differently compared with more naïve strains. Whether this is simply a necessary accommodation to the persistence phenotype or if metabolism plays a direct role in achieving persistence in the host is still unclear. Here, we characterize a convergent shift in metabolic function(s) linked with the persistence phenotype during Pseudomonas aeruginosa colonization in the airways of people with cystic fibrosis. We show that clinically relevant mutations in the key metabolic enzyme, pyruvate dehydrogenase, lead to a host-specialized metabolism together with a lower virulence and immune response recruitment. These changes in infection phenotype are mediated by impaired type III secretion system activity and by secretion of the antioxidant metabolite, pyruvate, respectively. Our results show how metabolic adaptations directly impinge on persistence and pathogenicity in this organism. he role of metabolism in bacterial persistence during infections is not clear. This study shows that host-specialized metabolic adaptations in Pseudomonas aeruginosa reduce virulence and immune responses in cystic fibrosis patients. [ABSTRACT FROM AUTHOR]

Background Objectives Materials and Methods Results Conclusions and Clinical Relevance Silver sulfadiazine (SSD) is commonly formulated into otic preparations to treat otitis externa, although evidence of stability and antimicrobial efficacy with long‐term storage is lacking.To evaluate the effect of storage time on chemical stability and in vitro antimicrobial activity of SSD diluted in sterile water, including two 1% suspensions using SSD pharmaceutical‐grade powder stored at room temperature (RT) in plastic or sterile glass bottles, and a 1:9 dilution using prescription SSD 1% cream stored at RT in a sterile glass bottle.Liquid chromatography–tandem mass spectrometry (LC–MS/MS) assessed chemical stability. Trimethoprim/sulfamethoxazole‐susceptible and trimethoprim/sulfamethoxazole‐resistant strains of Staphylococcus pseudintermedius (SP), meticillin‐resistant (MR) SP, S. schleiferi (SS), MRSS, Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli evaluated by 24 h time–kill analysis assessed in vitro antimicrobial efficacy. Each assessment was performed at zero, one, three and six months of storage.LC–MS/MS showed no significant change in concentration over time for any suspension. When adjusted for time and species/strain, all SSD suspensions showed significant reductions in colony forming units (cfu)/mL at 24 h (p < 0.001). Including all suspensions, a bactericidal effect (minimum 3‐log cfu/mL reduction at 24 h) occurred against 94% of total isolates, with failure against 33 of 552 isolates (6%). Bactericidal failure was more likely with the cream‐based suspension (p < 0.05) and at six months (p < 0.01).Powder‐based and cream‐based SSD/sterile water suspensions showed no significant change in concentration and demonstrated in vitro antimicrobial activity for six months. Bactericidal failure was more likely with the cream‐based suspension and after six months of storage. [ABSTRACT FROM AUTHOR]

The opportunistic bacterial pathogen Pseudomonas aeruginosa causes a wide range of infections that are difficult to treat, largely because of the spread of antibiotic-resistant isolates. Antivirulence therapy, í.e. the use of drugs that inhibit the expression or activity of virulence factors, is currently considered an attractive strategy to reduce P. aeruginosa pathogenicity and complement antibiotic treatments. Because of the multifactorial nature of P. aeruginosa virulence and the broad arsenal of virulence factors this bacterium can produce, the regulatory networks that control the expression of multiple virulence traits have been extensively explored as potential targets for antivirulence drug development. The intracellular signaling molecule diadenosine tetraphosphate (Ap4A) has been reported to control stress resistance and virulence-related traits in some bacteria, but its role has not been investigated in P. aeruginosa so far. To fill this gap, we generated a mutant of the reference strain P. aeruginosa PAO1 that lacks the Ap4A-hydrolysing enzyme ApaH and, consequently, accumulates high intracellular levels of Ap4A. Phenotypic and transcriptomic analyses revealed that the lack of ApaH causes a drastic reduction in the expression of several virulence factors, including extracellular proteases, elastases, siderophores, and quorum sensing signal molecules. Accordingly, infection assays in plant and animal models demonstrated that ApaH-deficient cells are significantly impaired in infectivity and persistence in different hosts, including mice. Finally, deletion of apaH in P. aeruginosa clinical isolates demonstrated that the positive effect of ApaH on the production of virulence-related traits and on infectivity is conserved in P. aeruginosa. This study provides the first evidence that the Ap4A-hydrolysing enzyme ApaH is important for P. aeruginosa virulence, highlighting this protein as a novel potential target for antivirulence therapies against P. aeruginosa. Author summary: Novel therapeutic interventions are urgently needed to address the threat of antimicrobial resistance. Inhibition of the virulence potential of bacterial pathogens, the so called antivirulence approach, is an alternative or complementary strategy to standard antibiotic-based therapies. The identification of suitable targets is essential to promote and advance antivirulence drug discovery programs. By combining in vitro analyses and in vivo infection assays, we demonstrated that the enzyme ApaH, which is responsible for the degradation of the intracellular signaling molecule diadenosine tetraphosphate, contributes to the virulence of the important human pathogen Pseudomonas aeruginosa. Indeed, loss of ApaH drastically reduces the production of several virulence factors in both laboratory and clinical isolates, and impairs P. aeruginosa ability to cause infection in plant, insect and rodent models. These results, together with the absence of ApaH homologues in mammals, make ApaH a promising target for the development of anti-P. aeruginosa antivirulence drugs. [ABSTRACT FROM AUTHOR]

Phage therapy is a promising antibacterial strategy, especially given that drugresistant bacterial infections are escalating worldwide. Because phages are not active against all strains of a given species, phages being considered for therapeutic use would ideally be tested against bacterial isolates from individual patients prior to administration. Standardized, clinically validated phage susceptibility testing (PST) methods are needed for assessing in vitro phage activity. This study compared two high-throughput liquid-based PST assays. The first, using the Biolog Omnilog™, assessed changes in microbial respiration leading to color changes based on a tetrazolium dye. The second, Agilent BioTek Cytation 7, assessed changes in optical density. Both used 96-well microtiter plate formats. A total of 55 diverse phages with activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, or Enterococcus faecalis were studied against their respective susceptible bacterial hosts and non-susceptible controls, with susceptibility defined based on plaque assay. PST was performed by both assays in replicates, with results compared in terms of hold times (time through which bacterial growth is inhibited by phage compared to controls). Coefficients of variance and interclass correlation coefficients were used to assess inter- and intra-assay reproducibility. Based on a ≤50% coefficient of variance cutpoint, 87% of Biolog and 84% of Agilent assays were considered valid for susceptible bacteria, with 100% considered valid for non-susceptible bacteria by both systems. Using a 8 h hold time cutpoint, 100% of the results matched between the two assays. The interclass correlation coefficient showed 26% excellent agreement, 35% good agreement, and 17% moderate agreement between the two assays for susceptible isolates and 100% excellent agreement for non-susceptible isolates. Overall, the assays compared provided good/fair statistical reproducibility for the assessment of phage susceptibility. [ABSTRACT FROM AUTHOR]