Gram-negative Pathogens Research Articles

Quorum Quenching Approaches against Bacterial-Biofilm-Induced Antibiotic Resistance.

With the widespread phenomenon of antibiotic resistance and the diffusion of multiple drug-resistant bacterial strains, enormous efforts are being conducted to identify suitable alternative agents against pathogenic microorganisms. Since an association between biofilm formation and antibiotic resistance phenotype has been observed, a promising strategy pursued in recent years focuses on controlling and preventing this formation by targeting and inhibiting the Quorum Sensing (QS) system, whose central role in biofilm has been extensively demonstrated. Therefore, the research and development of Quorum Quenching (QQ) compounds, which inhibit QS, has gradually attracted the attention of researchers and has become a new strategy for controlling harmful microorganisms. Among these, a number of both natural and synthetic compounds have been progressively identified as able to interrupt the intercellular communication within a microbial community and the adhesion to a surface, thus disintegrating mature/preformed biofilms. This review describes the role played by QS in the formation of bacterial biofilms and then focuses on the mechanisms of different natural and synthetic QS inhibitors (QSIs) exhibiting promising antibiofilm ability against Gram-positive and Gram-negative bacterial pathogens and on their applications as biocontrol strategies in various fields.

Effect of Nitrogen Doping on the Photocatalytic Properties and Antibiofilm Efficacy of Reduced TiO2 Nanoparticles.

Nanomaterial-mediated antibacterial photodynamic therapy (aPDT) emerges as a promising treatment against antibiotic-resistant bacterial biofilms. Specifically, titanium dioxide nanoparticles (TiO2 NPs) are being investigated as photosensitizers in aPDT to address biofilm related diseases. To enhance their photocatalytic performance in the visible spectral range for biomedical applications, various strategies have been adopted, including reduction of TiO2 NPs. However, despite improvements in visible-light photoactivity, reduced TiO2 NPs have yet to reach their expected performance primarily due to the instability of oxygen vacancies and their tendency to reoxidize easily. To address this, we present a two-step approach to fabricate highly visible-light active and stable TiO2 NP photocatalysts, involving nitrogen doping followed by a magnesium-assisted reductive annealing process. X-ray photoelectron spectroscopy analysis of the synthesized reduced nitrogen-doped TiO2 NPs (H:Mg-N-TiO2 NPs) reveals that the presence of nitrogen stabilizes oxygen vacancies and reduced Ti species, leading to increased production of reactive oxygen species under visible-light excitation. The improved aPDT efficiency translates to a 3-fold enhancement in the antibiofilm activity of nitrogen-doped compared to undoped reduced TiO2 NPs against both Gram-positive (Streptococcus mutans) and Gram-negative (Porphyromonas gingivalis, Fusobacterium nucleatum) oral pathogens. These results underscore the potential of H:Mg-N-TiO2 NPs in aPDT for combating bacterial biofilms effectively.

CTC-177, a novel drug-Fc conjugate, shows promise as an immunoprophylactic agent against multidrug-resistant Gram-negative bacterial infections.

The widespread emergence of antibiotic resistance including MDR in Gram-negative bacterial pathogens poses a critical challenge to the current antimicrobial armamentarium. To create a novel drug-Fc conjugate (DFC) that can be delivered at sustained and prolonged levels while simultaneously activating the host immune response to combat MDR Gram-negative infections. The Cloudbreak™ platform was used to develop DFCs consisting of a targeting moiety (TM) (a polymyxin-derived dimer) attached via a non-cleavable linker to an effector moiety (EM) (the Fc domain of human IgG1). In vitro activities of the DFCs were assessed by MIC testing. Neutropenic mouse models of thigh infection, septicaemia and pneumonia were used to evaluate in vivo efficacy. Pharmacokinetics were evaluated in mice and cynomolgus monkeys. A single prophylactic dose of our lead DFC, CTC-177, resulted in significantly decreased bacterial burdens and reduced inflammation comparable to daily treatment with colistin in septicaemia and pneumonia mouse models. Furthermore, CTC-177 prophylaxis was able to restore colistin efficacy in colistin-resistant septicaemia, reducing bacterial burdens beyond the limit of detection. Finally, CTC-177 displayed a long terminal half-life of over 24 and 65 h in mice and cynomolgus monkeys, respectively. These data support the continued development of Cloudbreak™ DFCs as broad-spectrum prophylactic agents against Gram-negative infections.

Navigating fluoroquinolone resistance in Gram-negative bacteria: a comprehensive evaluation.

Since the introduction of quinolone and fluoroquinolone antibiotics to treat bacterial infections in the 1960s, there has been a pronounced increase in the number of bacterial species that have developed resistance to fluoroquinolone treatment. In 2017, the World Health Organization established a priority list of the most critical Gram-negative resistant pathogens. These included Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli. In the last three decades, investigations into the mechanisms of fluoroquinolone resistance have revealed that mutations in the target enzymes of fluoroquinolones, DNA gyrase or topoisomerase IV, are the most prevalent mechanism conferring high levels of resistance. Alterations to porins and efflux pumps that facilitate fluoroquinolone permeation and extrusion across the bacterial cell membrane also contribute to the development of resistance. However, there is a growing observation of novel mutants with newer generations of fluoroquinolones, highlighting the need for novel treatments. Currently, steady progress has been made in the development of novel antimicrobial agents that target DNA gyrase or topoisomerase IV through different avenues than current fluoroquinolones to prevent target-mediated resistance. Therefore, an updated review of the current understanding of fluoroquinolone resistance within the literature is imperative to aid in future investigations.

Ineffectiveness of carbapenems in real-world clinical practice according to therapeutic drug monitoring data and Roszdravnadzor AIS reports

Relevance. The use of carbapenems is associated with significant variability in pharmacokinetics/pharmacodynamics (FC/PD) parameters, particularly in critically ill patients. The combination of variability in these parameters and standardized dosing regimens can lead to irrational dosing, excessively high or low doses, and consequently less effective treatment and resistance. Optimal management of these factors is essential for combating the development of resistance, particularly for reserve antibiotics.The aim of this study was to evaluate the achievement of the target levels of carbapenems (imipenem/cilastatin) in plasma concentrations in patients with burn injury based on therapeutic drug monitoring and to analyze spontaneous reports registered in the AIS Roszdravnadzor database regarding the effectiveness of therapy.Methods. The analysis included patients receiving antibiotic therapy with imipenem/cilastatin in the burn unit for adults at the University Hospital of the Volga Region Research Medical University for burn trauma who were hospitalized from 01.03.2023 to 30.06.2023. The study was conducted without correcting the trade name of imipenem/cilastatin. Therapeutic drug monitoring was performed after the 4th administration of imipenem/cilastatin. Blood was drawn at 3 h (1st sample), 5 h (2nd sample), and 8 h (3rd sample) after infusion in a clotting activator tube. The analysis was performed using a liquid chromatograph "LC-20 Prominance" (Shimadzu, Japan) in reversed-phase mode with a matrix photodiode detector for UV and visible spectra. Data processing was performed using the LCsolution program. Spontaneous reports regarding the use of carbapenems recorded in the AIS of Roszdravnadzor from January 2020 to November 2023 were also analyzed as the object of the study.Results. The results of the study of carbapenems (imipenem/cilastatin) concentration level achievement in the plasma of patients with burn injury showed that the effective imipenem concentration exceeding the MPC value in relation to the isolated Gram-negative pathogen was found only in 1 out of 5 patients included in the study. Two patients showed dynamically changing IPC values during treatment, indicating the necessity of therapeutic drug monitoring, as well as the probability of failure to achieve target concentrations and optimal FC/FD values. In another two patients, imipenem concentrations were insufficient to maintain optimal FC/PD values, indicating that the antimicrobial regimen was ineffective. An analysis of spontaneous reports registered in the AIS of Roszdravnadzor regarding identified cases of the ineffectiveness of carbapenems (imipenem/cilastatin, meropenem) revealed 5,2% of reports regarding meropenem and 1.4% regarding imipenem/cilastatin in the total structure of reports.Conclusion. The implementation of therapeutic drug monitoring procedures can reduce therapy ineffectiveness and antibiotic resistance through personalized antimicrobial dosing.

Enhancing food preservation and safety: Synergistic effects of Allium-derived organosulfur compounds and outer membrane permeabilization peptide L-11

Ready-to-eat (RTE) foods, characterized by the lack of a terminal heating step prior to consumption, offer enhanced organoleptic qualities compared to their cooked counterparts, as they retain more of their natural flavors, textures, and nutritional content. However, these untreated products pose a risk for foodborne illnesses if not promptly consumed and/or adequately stored under refrigeration or in a frozen state. This investigation delves into the synergistic antimicrobial effects of a novel human-mimetic peptide, L-11, in conjunction with organosulfur compounds derived from Allium species—namely allicin, diallyl sulfide (DAS), dipropyl sulfide (DPS), propyl propane thiosulfinate (PTS), and propyl propane thiosulfonate (PTSO)—on the inhibition and control of Gram-negative foodborne pathogens across various food matrices. Notably, despite the minimal individual antimicrobial activity of peptide L-11 and the evaluated organosulfur compounds against target bacteria (Escherichia coli, Salmonella enterica, Yersinia enterocolitica, and Shigella sonnei), their combinations exhibited remarkable synergistic effects in vitro with until 32-fold reduction for some combinations. Specifically, combinations including PTS and PTSO demonstrated up to a 99% reduction in bacterial proliferation within RTE food models such as salmorejo, aioli, pumpkin cream, and spinach cream. These findings highlight the potential applications of these synergistic combinations in extending the shelf-life and enhancing the safety of RTE foods. To the best of our knowledge, this represents the inaugural report of such synergistic interactions between organosulfur compounds and peptides in extending the shelf-life of RTE foods.

Evolving resistance landscape in gram-negative pathogens: An update on β-lactam and β-lactam-inhibitor treatment combinations for carbapenem-resistant organisms.

Antibiotic resistance has become a global threat as it is continuously growing due to the evolution of β-lactamases diminishing the activity of classic β-lactam (BL) antibiotics. Recent antibiotic discovery and development efforts have led to the availability of β-lactamase inhibitors (BLIs) with activity against extended-spectrum β-lactamases as well as Klebsiella pneumoniae carbapenemase (KPC)-producing carbapenem-resistant organisms (CRO). Nevertheless, there is still a lack of drugs that target metallo-β-lactamases (MBL), which hydrolyze carbapenems efficiently, and oxacillinases (OXA) often present in carbapenem-resistant Acinetobacter baumannii. This review aims to provide a snapshot of microbiology, pharmacology, and clinical data for currently available BL/BLI treatment options as well as agents in late stage development for CRO harboring various β-lactamases including MBL and OXA-enzymes.

The antibiotic resistance crisis and the development of new antibiotics.

The Global Burden of Disease report of 2019 estimated 14 million infection-related deaths, making it the second leading cause of death after ischaemic heart disease. Bacterial pathogens accounted for 7.7 million deaths and deaths attributable to bacterial antibiotic resistance amounted to 1.3 million, describing a clear demand for novel antibiotics. Antibiotic development had its golden age in 1930-1960. Following failures in the screening of chemical libraries for novel antibiotics at the beginning of this century, the high cost of launching new antibiotics (estimated at US$ 1.4 billion per registered drug) and difficulties in achieving a return of investment for novel antibiotics, pharmaceutical industry has mostly left the field. The current Lilliput review analyses the question whether scientific or economic hurdles prevented the registration of new antibiotics. Scientifically, substantial progress has been achieved over recent years to define the chemical properties needed to overcome the permeation barrier in Gram-negative pathogens; in extending the chemical space of antibiotic candidates by full modular synthesis of suitable molecules; by extending bioprospecting to previously 'unculturable' bacteria or unusual bacteria; by attacking bacterial targets on the outer bacterial membrane; and by looking for support from structural biology, genomics, molecular genetics, phylogenetic analyses and deep machine learning approaches. However, these research activities were mostly conducted by academic researchers and biotech companies with limited financial resources. It thus seems that the development of new antibiotics, frequently described as the drying of the pipeline, is less limited by lack of scientific insight than by lack of the mobilization of the monetary resources needed to bring these discoveries to the market despite recent financial push and pull efforts of the public sector.

Pre- and Post-debridement Wound Cultures in Gustilo Type III Open Tibial Fractures to Predict Wound Infection at a Tertiary Care Hospital.

Gustilo type III open tibial fractures are difficult injuries that carry a higher risk of infection and other consequences. Open-fracture wound microbiology is dynamic and responsible for change over time. Effective antibiotic treatment plans are required, as detrimental microorganisms are often linked to these types of lesions. The study aimed to determine whether pre- and post-debridement wound cultures could predict wound infection in Gustilo type III open tibial fractures. This prospective study was carried out at the National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR) in Dhaka, Bangladesh, on 344 patients who presented to the emergency department with a Gustilo type III open tibial fracture within 24 hours of injury from June 2018 to October 2019. Three successive cultures were carried out: one in the emergency room (surveillance culture), the second at the emergency theater after debridement, and the third in the ward after one week (seven to 10 days). Statistical analyses of the results were conducted using Microsoft Excel (Microsoft Corp., Redmond, WA) and IBM SPSS Statistics for Windows, version 27 (IBM Corp., Armonk, NY). The study included 344 patients with an average age of 37.15 years, with motor vehicle accidents being the primary cause (78.2%). Gustilo type IIIA fractures made up the majority (48.5%), followed by type IIIB fractures (44.8%). A significant reduction in contamination rates was observed from initial admission (48.8%) to post-debridement (36.6%) (p =.001). There was a significant positive correlation between pre-debridement cultures and wound infections (r =.311), as well as between post-debridement cultures and wound infections. The infection rate increased to 61.6% in ward samples, indicating a high rate of hospital-acquired infections. Pseudomonas and Klebsiella species were the most prevalent multidrug-resistant bacteria that caused these infections. The present study provides information on the relationship between contamination and infection. Gram-negative pathogens were dominant in this study, and the results of the antibiograms showed an alarming pattern of resistance. Nosocomial infection demands further urgent study.

Exploring Fe(III) coordination and membrane interaction of a siderophore-peptide conjugate: Enhancing synergistically the antimicrobial activity

Many microbes produce siderophores, which are extremely potent weapons capable of stealing iron ions from human tissues, fluids and cells and transferring them into bacteria through their appropriate porins. We have recently designed a multi-block molecule, each block having a dedicated role. The first component is an antimicrobial peptide, whose good effectiveness against some bacterial strains was gradually improved through interactive sequence modifications. Connected to this block is a flexible bio-band, also optimized in length, which terminates in a hydroxyamide unit, a strong metal binder. Thus, the whole molecule brings together two pieces that work synergistically to fight infection. To understand if the peptide unit, although modified with a long tail, preserves the structure and therefore the antimicrobial activity, and to characterize the mechanism of interaction with bio-membrane models mimicking Gram-negative membranes, we performed a set of fluorescence-based experiments and circular dichroism studies, which further supported our design of a combination of two different entities working synergistically. The chelating activity and iron(III) binding of the peptide was confirmed by iron(III) paramagnetic NMR analyses, and through a competitive assay with ethylenediamine-tetra acetic acid by ultraviolet–visible spectroscopy. The complexation parameters, the Michaelis constant K, and the number of sites n, evaluated with spectrophotometric techniques are confirmed by Fe(III) paramagnetic NMR analyses here reported. In conclusion, we showed that the coupling of antimicrobial capabilities with iron-trapping capabilities works well in the treatment of infectious diseases caused by Gram-negative pathogens.

Development and characterisation of agar/silver nanoparticles-based film from Gracilaria canaliculata for food packaging

Gracilaria canaliculata was used as a novel source to extract agar, and for the green synthesis of silver nanoparticles. Silver nanoparticles (0.1 - 0.3%) were incorporated into the agar matrix to develop an environment-friendly food packaging material using the solution casting method. The concentration of nanoparticles affected the physical, thermal, and mechanical properties of the films. Films containing higher concentrations of silver nanoparticles exhibited promising properties, and demonstrated strong antimicrobial activity against both Gram-negative and Gram-positive foodborne pathogens. The film formulation exhibited no cytotoxic effect on HepG2 cells, with cell viability exceeding 94%. These findings suggested that the film possessed favourable characteristics for use as a food packaging material, presenting a potential alternative to plastics.

Evolutionary trends indicate a coherent organization of sap operons

Human hosts possess a complex network of immune responses against microbial pathogens. The production of antimicrobial peptides (AMPs), which target the pathogen cell membranes and inhibit them from inhabiting the hosts, is one such mechanism. However, pathogens have evolved systems that encounter these host-produced AMPs. The Sap (sensitivity to antimicrobial peptides) transporter uptakes AMPs inside the microbial cell and proteolytically degrades them. The Sap transporters comprise five subunits encoded by genes in an operon. Despite its ubiquitous nature, its subunits are not found to be in tandem with many organisms. In this study, a total of 421 Sap transporters were analyzed for their operonic arrangement. Out of 421, a total of 352 operons were found to be in consensus arrangement, while the remaining 69 show a varying arrangement of genes. The analysis of the intergenic distance between the subunits of the sap operon suggests a signature pattern with sapAB (-4), sapBC (-14), sapCD (-1), and sapDF (-4 to 1). An evolutionary analysis of these operons favors the consensus arrangement of the Sap transporter systems, substantiating its prevalence in most of the Gram-negative pathogens. Overall, this study provides insight into bacterial evolution, favoring the maintenance of the genetic organization of essential pathogenicity factors.

Temporal decreases in pathogen colonization and infection among hospitalized neonates following routine skin antisepsis with chlorhexidine gluconate: Botswana 2022 – 2023

Background: Multidrug-resistant Gram-negative bacteria are a major cause of sepsis among hospitalized neonates globally. Aqueous chlorhexidine gluconate (CHG) skin antisepsis has been shown to be safe for use in infants; however, its sustained effectiveness in preventing Gram-negative pathogen colonization, bloodstream infection (BSI), and mortality is unclear. Methods: We conducted a period prevalence survey, with 26 sampling events over 12 months (18 October 2022 – 31 October 2023) at a 33-bed neonatal unit in a tertiary public hospital in Botswana where ESBL-producing Klebsiella pneumoniae and carbapenem-resistant Acinetobacter baumannii are leading causes of BSI. Perirectal and periumbilical skin swabs were collected every two weeks from all inpatients. Swabs were inoculated onto chromogenic media selective and differential for extended-spectrum beta-lactamase producing Enterobacterales (ESBL-E) and Acinetobacter spp. (CHROMagar™ ESBL, Acinetobacter). Colonization status was determined based on culture growth and colony morphology. Contemporaneous data on all-cause mortality and BSI were abstracted from routine surveillance records. Pre- and post-CHG prevalences were compared using a simple Chi-square test. During the surveillance period, an outbreak of K. pneumoniae linked to contaminated multi-use vials was detected, thus BSIs and deaths during the outbreak period (2 February–6 April, 2023) were excluded. In February 2023, the hospital infection prevention and control (IPC) team introduced twice-weekly whole-body cleansing with commercially available 2% aqueous CHG, performed by caregivers and healthcare workers on neonates >24 hours old and weighing ≥1 kg until discharge. Results: There were significant decreases in ESBL-E and Acinetobacter skin and perirectal colonization following the CHG intervention (Table 1; Figure 1). After the CHG intervention, the incidence of Acinetobacter BSIs declined significantly and there was a trend toward a decline in other BSIs and mortality. No adverse events associated with CHG were reported. Conclusions: Twice-weekly CHG application was temporally associated with significant reductions in neonatal ESBL-E and Actinetobacter skin and perirectal colonization and Acinetobacter BSI. This analysis was limited by a short pre-intervention surveillance period and thus may have been influenced by confounders such as seasonality, and intensified IPC efforts following the outbreak. Analysis of the routine CHG use in other settings and over longer surveillance periods are needed to better understand its effectiveness as an IPC strategy in settings where neonatal sepsis incidence is high. Table 1. Colonization prevalence, BSI incidence, and mortality surrounding introduction of CHG skin cleansing in a neonatal unit, 18 October 2022 – 31 October 2023.

Transition transferases prime bacterial capsule polymerization.

Capsules are long-chain carbohydrate polymers that envelop the surfaces of many bacteria, protecting them from host immune responses. Capsule biosynthesis enzymes are potential drug targets and valuable biotechnological tools for generating vaccine antigens. Despite their importance, it remains unknown how structurally variable capsule polymers of Gram-negative pathogens are linked to the conserved glycolipid anchoring these virulence factors to the bacterial membrane. Using Actinobacillus pleuropneumoniae as an example, we demonstrate that CpsA and CpsC generate a poly(glycerol-3-phosphate) linker to connect the glycolipid with capsules containing poly(galactosylglycerol-phosphate) backbones. We reconstruct the entire capsule biosynthesis pathway in A. pleuropneumoniae serotypes 3 and 7, solve the X-ray crystal structure of the capsule polymerase CpsD, identify its tetratricopeptide repeat domain as essential for elongating poly(glycerol-3-phosphate) and show that CpsA and CpsC stimulate CpsD to produce longer polymers. We identify the CpsA and CpsC product as a wall teichoic acid homolog, demonstrating similarity between the biosynthesis of Gram-positive wall teichoic acid and Gram-negative capsules.

Emergence Characteristics of Fire Blight from 2019 to 2023 in Korea

Erwinia amylovora is a gram-negative plant pathogen that causes fire blight in apple and pear trees, resulting in significant damage worldwide. In this study, we monitored the emergence of fire blight from 2019 to 2023 to determine the emergence patterns and the factors affecting the outbreak of the disease. As a result of the 5-year survey on the emergence of fire blight, a total of 2,029 cases have emerged, mostly in apple trees of 1,378 cases (67.9%) followed by 645 cases (31.8%) in pear trees, and from quince, hawthorn, and mountain ash trees. Fire blight appeared in specific areas of Gyeonggi, Chungnam, Gangwon, and Chungbuk provinces in 2019, but spread to Andong and Yesan in 2021, Muju and Bonghwa in 2023. In 2020 and 2021, there were 744 and 618 cases of fire blight outbreaks, respectively, compared to other years (188–245 cases/year). Notably, 914 of these cases were observed in apple trees from May to July, with 667 cases reported in Chungju and Jecheon. The incidence of fire blight was positively correlated with the daily maximum temperatures and rainy days in January and February, as well as the rainy days in May and June. The average age of the diseased pear trees was 25 years, higher than the 10-year average age of the apple trees. This study provides fundamental information to understand the status and factors affecting the fire blight emergence in Korea. Prevention measures should be established through continuous analysis of the status of fire blight.

Rejuvenation of Meropenem by Conjugation with Tilapia Piscidin-4 Peptide Targeting NDM-1 Escherichia coli.

Gram-negative pathogens that produce β-lactamases pose a serious public health threat as they can render β-lactam antibiotics inactive via hydrolysis. This action contributes to the waning effectiveness of clinical antibiotics and creates an urgent need for new antimicrobials. Antimicrobial peptides (AMPs) exhibiting multimodal functions serve as a potential source in spite of a few limitations. Thus, the conjugation of conventional antibiotics with AMPs may be an effective strategy to leverage the advantages of each component. In this study, we conjugated meropenem to the AMP Tilapia piscidin 4 (TP4) using a typical coupling reaction. The conjugate was characterized by using HPLC-MS, HR-MS, and MS-MS fragmentation analysis. It was then evaluated in terms of antibacterial potency, hemolysis, and cytotoxicity toward RAW264.7 and CCD-966SK cell lines. The conjugation of meropenem with TP4 significantly reduced the cytotoxicity compared to TP4. Conjugation of unprotected TP4 with meropenem resulted in cross-linking at the N-terminal and lysine sites. The structural activity relationship of the two isomers of the TP4-meropenem conjugate was investigated. Both the isomers showed notable antibacterial activities against NDM-1 Escherichia coli and reduced red blood cell hemolysis as compared to TP4. Lysine conjugate (TP4-K-Mero) showed lesser hemolysis than the N-terminal conjugate (TP4-N-Mero). Molecular modeling further revealed that the conjugates can bind to lipopolysaccharides and inhibit NDM-1 β-lactamase. Together, these data show that conjugation of antibiotics with AMP can be a feasible approach to increase the therapeutic profile and effectively target multidrug-resistant pathogens. Furthermore, antibiotic conjugation at different AMP sites tends to show unique biological properties.

A Novel Multi-epitope Vaccine Based on Virulence Stimulating Two-component Protein EsrA Against Fish Pathogenic Edwardsiella tarda – An Immunoinformatic Approach

Edwardsiellosis, caused by the gram-negative pathogen Edwardsiella tarda, is a major global aquaculture threat. Despite vaccination being a potential strategy, development of effective vaccines remains a challenge. The study aimed to develop a multi-epitope vaccine (EsrAmev) against virulent EsrA antigen in fish pathogenic E. tarda using an immunoinformatic approach. The study identified antigenic, non-allergenic, and nontoxic epitopes for cytotoxic T lymphocytes, helper T-lymphocytes, and linear Blymphocytes. They were combined to create the EsrAmev construct, with TLR4 agonist added for the immunogenicity. The physiochemical analysis of EsrAmev by ProtParam server showed a molecular weight of 29 kDa, an antigenicity score of 0.5966, and a solubility of 0.823563 with immunogenic, non-allergenic and non-toxic properties. Robetta, Mod, and Galaxy refiner servers refined the EsrAmev 3D structure, achieving 97.4% RAMA-favoured region, stable interactions, binding stability, and structural stiffness with TLR4 receptor. The EsrAmev construct, optimized for high immune responses in Escherichia coli K12 model, was successfully cloned into the pET28a (+) vector in silico for future wet lab applications. These findings suggests that the EsrAmev multi-epitope vaccine might have potential for the prophylaxis of E.tardacausing Fish Edwardsiellosis.

Trends in Empiric Broad-Spectrum Antibiotic Use for Suspected Community-Onset Sepsis in US Hospitals

Little is known about the degree to which suspected sepsis drives broad-spectrum antibiotic use in hospitals, what proportion of antibiotic courses are unnecessarily broad in retrospect, and whether these patterns are changing over time. To describe trends in empiric broad-spectrum antibiotic use for suspected community-onset sepsis. This cross-sectional study used clinical data from adults admitted to 241 US hospitals in the PINC AI Healthcare Database. Eligible participants were aged 18 years or more and were admitted between 2017 and 2021 with suspected community-onset sepsis, defined by a blood culture draw, lactate measurement, and intravenous antibiotic administration on admission. Empiric anti-methicillin-resistant Staphylococcus aureus (MRSA) and/or antipseudomonal β-lactam agent use. Annual rates of empiric anti-MRSA and/or antipseudomonal β-lactam agent use and the proportion that were likely unnecessary in retrospect based on the absence of β-lactam resistant gram-positive or ceftriaxone-resistant gram-negative pathogens from clinical cultures obtained through hospital day 4. Annual trends were calculated using mixed-effects logistic regression models, adjusting for patient and hospital characteristics. Among 6 272 538 hospitalizations (median [IQR] age, 66 [53-78] years; 443 465 male [49.6%]; 106 095 Black [11.9%], 65 763 Hispanic [7.4%], 653 907 White [73.1%]), 894 724 (14.3%) had suspected community-onset sepsis, of whom 582 585 (65.1%) received either empiric anti-MRSA (379 987 [42.5%]) or antipseudomonal β-lactam therapy (513 811 [57.4%]); 311 213 (34.8%) received both. Patients with suspected community-onset sepsis accounted for 1 573 673 of 3 141 300 (50.1%) of total inpatient anti-MRSA antibiotic days and 2 569 518 of 5 211 745 (49.3%) of total antipseudomonal β-lactam days. Between 2017 and 2021, the proportion of patients with suspected sepsis administered anti-MRSA or antipseudomonal therapy increased from 63.0% (82 731 of 131 275 patients) to 66.7% (101 003 of 151 435 patients) (adjusted OR [aOR] per year, 1.03; 95% CI, 1.03-1.04). However, resistant organisms were isolated in only 65 434 cases (7.3%) (30 617 gram-positive [3.4%], 38 844 gram-negative [4.3%]) and the proportion of patients who had any resistant organism decreased from 9.6% to 7.3% (aOR per year, 0.87; 95% CI, 0.87-0.88). Most patients with suspected sepsis treated with empiric anti-MRSA and/or antipseudomonal therapy had no resistant organisms (527 356 of 582 585 patients [90.5%]); this proportion increased from 88.0% in 2017 to 91.6% in 2021 (aOR per year, 1.12; 95% CI, 1.11-1.13). In this cross-sectional study of adults admitted to 241 US hospitals, empiric broad-spectrum antibiotic use for suspected community-onset sepsis accounted for half of all anti-MRSA or antipseudomonal therapy; the use of these types of antibiotics increased between 2017 and 2021 despite resistant organisms being isolated in less than 10% of patients treated with broad-spectrum agents.

Prevalence and clinical implications of bloodstream infections in intensive care patients with or without burn injury: a retrospective cohort study

PurposeSevere burn injuries are often accompanied by infections and associated with high morbidity and mortality. This study aimed to compare the prevalence and clinical impact of bacteremia between patients receiving intensive care with and without burns.MethodsThis single-center retrospective cohort study at the University Hospital Vienna, Austria, analyzed blood cultures from intensive care unit (ICU) patients with and without burns (2012–2022) to assess the prevalence of bacteremia, the associated pathogen distribution and the 60-day all-cause mortality.ResultsIn 1170 ICU patients, 303 with burns and 867 without, the prevalence of bacteremia was similar among patients with at least one blood culture (31/157 [19.7%] versus 44/213 [20.7%], OR [95%CI] = 0.95 [0.57–1.57]). Burn patients exhibited a significantly higher frequency of microbiological sampling (51.5% versus 24.5%, p < 0.001), resulting in a higher overall prevalence of bacteremia (10.2% versus 5.1%, p = 0.002). 16.2% of all identified pathogens were multidrug-resistant (MDR). The 60-day all-cause mortality was higher in patients with MDR pathogens than in patients without bacteremia (41.7% versus 10.6%, p = 0.026).ConclusionBacteremia prevalence was similar in burn and non-burn patients, with high rates of multidrug-resistant Gram-negative pathogens. The 60-day all-cause mortality was significantly higher in patients with MDR pathogens than in patients without bacteremia.

Pseudomonas aeruginosa impairs mitochondrial function and metabolism during infection of corneal epithelial cells.

Pseudomonas aeruginosa (PA) is a gram-negative opportunistic pathogen that can infect the cornea as a result of trauma or contact lens wear. In addition to their known energy producing role, mitochondria are important mediators of immune signaling and host defense. While certain pathogens have developed strategies to evade host defenses by modulating host mitochondrial dynamics and metabolism, the ability of PA to harness host cell mitochondria during corneal infection is unknown. Using a combination of biochemical and imaging techniques, we show that PA infection of corneal epithelial cells induced mitochondrial fission in a DRP1-dependent manner that preceded PINK1/Parkin and FUNDC1-mediated mitophagy. PA also impaired NADH-linked respiration through a reduction in complex 1. This corresponded to a decrease in metabolic pathways related to glycolysis and the TCA cycle. Metabolomics analysis further demonstrated an upregulation of the pentose phosphate pathway, arginine, purine, and pyrimidine metabolism in PA infected cells. These pathways may provide a key source of nucleotides, amino acids, and nitrogen for both the host cell and PA, in addition to antioxidant functions. Following treatment with gentamicin to kill all extracellular bacteria, metabolic flux analysis showed that corneal epithelial cells were able to restore mitochondrial function despite the continued presence of intracellular PA. Taken together, these data demonstrate that mitochondrial dysfunction and metabolic rewiring in host cells is triggered by extracellular PA, but once inside, PA requires healthy mitochondria to ensure host cell survival.