Global Threat Research Articles

Fe-based nanozyme with photothermal activity prepared from polymerization-induced self-assembly assays boosts the recovery of bacteria-infected wounds

Nowadays, the overuse of antibiotics has escalated bacterial infections into an increasingly severe global health threat. Developing non-antibiotic treatments has emerged as a promising strategy for treating bacterial infections. Notably, nanozyme-based composite materials have garnered growing interest. Therefore, the efficient preparation of nanozyme is important. Herein, we have presented an efficient method to prepare Fe-based nanozyme through polymerization-induced self-assembly assay to kill bacteria efficiently, which could significantly enhance the healing of infected wounds. Through polymerization-induced self-assembly assay, a large number of uniformly sized micelles, bearing imidazole groups, could be efficiently prepared. These nanoparticles subsequently chelate with Fe ions, followed by pyrolysis and etching processes, resulting in the production of uniformly small-sized nanozymes with high adsorption activity in the near-infrared region. The composite materials could effectively eradicate bacteria via a synergistic strategy of photothermal and catalytic therapies under infected microenvironments. In vivo animal models with full-thickness wounds showed that combination therapy not only eradicates 98 % of the bacteria but also significantly accelerates wound healing. This work underscores the utility of polymerization-induced self-assembly in the preparation of nanozymes and reveals promising applications of nanozymes in wound healing. Statement of significanceThis research introduces a functional nanozyme with photothermal activity, synthesized through polymerization-induced self-assembly, offering a promising non-antibiotic strategy to combat bacterial infections. This strategy enhances wound healing by combining photothermal and catalytic therapies, effectively eradicating drug-resistant bacteria while minimizing damage to healthy tissue. Our findings hold significant implications for the development of advanced antibacterial treatments and offer a robust assay to prepare nanozyme with small sizes. The prepared functional nanoparticles have a potential in wound healing, addressing a critical need in the face of rising antibiotic resistance.

Targeting the Ubiquitin Proteasome System to Combat Influenza A Virus: Hijacking the Cleanup Crew.

Influenza A virus (IAV) remains a significant global public health threat, causing substantial illness and economic burden. Despite existing antiviral drugs, the emergence of resistant strains necessitates alternative therapeutic strategies. This review explores the complex interplay between the ubiquitin proteasome system (UPS) and IAV pathogenesis. We discuss how IAV manipulates the UPS to promote its lifecycle, while also highlighting how host cells utilise the UPS to counteract viral infection. Recent research on deubiquitinases as potential regulators of IAV infection is also addressed. By elucidating the multifaceted role of the UPS in IAV pathogenesis, this review aims to identify potential targets for novel therapeutic interventions.

Genotypic Antimicrobial Resistance Profiles of Diarrheagenic Escherichia coli and Nontyphoidal Salmonella Strains Isolated from Children with Diarrhea and Their Exposure Environments in Ethiopia.

Antimicrobial resistance (AMR) poses a significant global threat, particularly in low- and middle-income countries, such as Ethiopia, where surveillance is limited. This study aimed to predict and characterize the AMR profiles of diarrheagenic Escherichia coli (DEC) and nontyphoidal Salmonella (NTS) strains isolated from human, animal, food, and environmental samples using whole genome sequencing. A total of 57 NTS and 50 DEC isolates were sequenced on an Illumina NextSeq 550. The ResFinder and PointFinder tools were employed to identify antimicrobial resistance genes (ARGs) and point mutations. Salmonella serotypes were determined using SeqSero. The analysis identified at least one ARG in every NTS sample and 78% of the DEC isolates, with 22 distinct ARGs in the NTS samples and 40 in the DEC samples. The most prevalent ARGs were aac(6')-Iaa and aph(3')-Ib, which predict aminoglycoside resistance in 100% of NTS and 54% of DEC isolates, respectively. Other commonly identified ARGs include sul2, aph(6)-Id, blaTEM-1B , and tet(A), which confer resistance to folate inhibitors, aminoglycosides, β-lactams, and tetracycline. Some ARGs predicted phenotypic multidrug resistance in both DEC and NTS isolates. All identified β-lactam ARGs, except for blaTEM -1D, conferred resistance to more than three antibiotics. Interestingly, blaCTX- M-15 was found to confer resistance to nine antibiotics, including third-generation cephalosporins, in 18% of DEC and 3.5% of NTS isolates. DEC isolates from children exhibited the highest ARG diversity. Notably, genes such as aph(3″)-Ib, aph(6)-Id, sul2, and tet(A) were detected across all sample types, including water sources, although some ARGs were exclusive to specific sample types. Point mutations mediating AMR were detected in several genes, with mutations associated with nucleotide substitution being the most frequent. This genotypic AMR profiling revealed the presence of widespread drug-resistant NTS and DEC strains in Ethiopia. Robust and sustained AMR surveillance is essential for monitoring the emergence and spread of these resistant pathogens.

A survey of US and Caribbean veterinary schools reveals strengths and opportunities in antimicrobial stewardship and infection prevention and control activities.

To understand antimicrobial stewardship (AS) and infection prevention and control (IPC) activities in veterinary schools. An online survey was completed by representatives from American Association of Veterinary Medical Colleges-accredited veterinary schools in the US and Caribbean prior to attending the Inaugural Small Animal Antimicrobial Stewardship Workshop for US Veterinary Schools. Responses were examined to identify patterns among AS and IPC activities and adherence to the AVMA core principles. Half (12 of 24) of the surveyed schools had an AS committee and most (79% [19 of 24]) had an IPC committee. Lack of dedicated staff time was a common barrier to AS (88% [21 of 24]) and IPC (75% [18 of 24]) reported by schools both with and without AS and IPC committees. Eleven of 24 schools (46%) reported performing at least 1 activity focused on each of the AVMA's 5 core principles of AS. Although 79% (19 of 24) of schools incorporate AS into preclinical curricula, training of clinical faculty (17% [4 of 24]), veterinary technicians and support staff (21% [5 of 24]), and house officers (42% [10 of 24]) is less common, despite these individuals engaging in teaching clinical-year veterinary students. Veterinary schools varied in established AS education and AS and IPC practices, though financial and human resources were a common barrier. A collaborative and cohesive approach to AS and IPC among schools to create sustainable frameworks for practice improvement will help combat the global threat of antimicrobial resistance. This is a critical action for settings where future veterinarians are trained.

Lemon Peel‐Extracted Recyclable Copper Oxide Nanoparticles for Methylene Blue Dye Adsorption: Optimization, Isotherms, Kinetics, Thermodynamics, and Reusability Study

AbstractResearchers are exploring sustainable methods for synthesizing metal oxide nanoparticles to address wastewater pollution, which poses a global threat to aquatic life and human health. The present research aims to biosynthesize recyclable Lemon peel‐extracted copper oxide nanoparticles (CuO NPs) to remove methylene blue dye via adsorption. Our approach involves a comprehensive range of techniques, such as FTIR, XRD, SEM‐EDX, Zeta potential, and UV‐VIS, to thoroughly characterize the NPs. SEM analysis confirmed that the CuO NPs, with an average size of 64.5 nm and a nearly spherical shape, exhibited a zeta potential value of – 16.34, indicating their relative stability. Optimized conditions for the 92.20% adsorption efficiency for methylene blue dye were pH at 6, contact time of 90 min, 0.06 g of adsorbent dose, 10 ppm dye conc., and Temp. 27 °C. Langmuir 1‐based maximum adsorption capacity (qm) was 617.28 mg/g for CuO NPs. Langmuir 1 and Freundlich are the most suitable isotherm models for experimental data, supporting Physi‐chemisorption and chemisorption as rate‐limiting steps in the exothermic adsorption process. A reusability study of up to three cycles proved the sustainability of the materials.

Assessing Microplastic Contamination in Shellfish: Insights from Pantai Remis Kuala Selangor, Strait of Malacca, Malaysia

Introduction: Microplastic (MP) contamination poses a global environmental threat, affecting terrestrial and marine ecosystems, and human health. This study investigates the presence, density, and composition of MPs in three commercially important shellfish species, oriental angel wing clam (Pholas orientalis), bamboo clam (Ensis leei), and blood cockles (Tegillarca granosa) at Pantai Remis Jeram, Kuala Selangor. Methods: Microplastics in shellfish were quantitatively analyzed for their abundance, colour, size, shape, and composition using microscopic techniques and micro-Fourier Transform Infrared (FTIR). Standard experimental protocols were followed. Statistical analysis of the data was performed using SPSS to identify correlations between these parameters. Results and Discussion: Our findings reveal a significant presence of MP particles in shellfish with T. granosa exhibiting the highest density (2.417 particles/cm³) compared to E. leei (0.721 particles/cm³) and P. orientalis (1.449 particles/cm³). Fibers and fragments were the dominant MP morphotypes, primarily in black color. P. orientalis and T. granosa contained a majority of MPs within the 1 - 5 mm size range, totalling 41 and 56 particles, respectively. Shellfish samples contain polymers of cellulase acetate and polyethylene terephthalate, indicating possible origins from plastic bottles and textile fibres. A statistically significant difference in the mean MP densities in the different species of shellfish was found by one-way ANOVA analysis (p = 0.042, p < 0.05). Conclusion: This study provides relevant data on MP pollution in commercially significant shellfish species. To effectively mitigate this environmental concern and comprehend the long-term ecological ramifications of MP intake by shellfish, more research is required.

Combating Antimicrobial Resistance by Resensitising Bacteria to Antibiotics Using CRISPR: A Narrative Review

Background: Antimicrobial resistance (AMR) remains a formidable global health threat. Conventional strategy of developing new antibiotics is costly and unsustainable. Thus, innovative approaches for resensitising bacteria using clustered regularly inter-spaced short palindromic repeats (CRISPR) technology are sought. Aims and Objectives: The aim of this study was to review existing technologies and approaches with the aim to identify the most feasible and practical approach to solve AMR globally. Methods: It is a narrative review of CRISPR research to identify a practical medical solution for combating AMR. By considering biological, social and pharmaceutical factors, feasible solutions and their limitations were identified. Next, CRISPR solutions were examined, then filtered based on strict medical expectations. A suitable cargo type and delivery mechanism will be established. Finally, the feasibility from a practical and economic perspective is considered. Results: Among the Cas effector modules examined, Cas12k was identified as the most promising candidate. Notably, Cas12k possesses a small protein size and lacks trans-cleavage activity, enhancing its specificity for targeted bacterial strains. Additionally, its naturally inactivated endonuclease domain further contributes to its precision. In line with this investigation, DNA plasmid was identified as the optimal cargo storage, while lipid nanoparticles were identified as the optimal delivery method. Conclusion: This is the first time an end-to-end consideration to AMR was considered for CRISPR-based strategies. This review offers valuable insights into a promising solution to addressing the AMR crisis. Such knowledge is essential to guide the development of novel AMR solutions.

Guanethidine Enhances the Antibacterial Activity of Rifampicin Against Multidrug-Resistant Bacteria

The escalating global threat of antibiotic resistance necessitates innovative strategies, such as the combination of antibiotics with adjuvants. Monotherapy with rifampicin is more likely to induce resistance in pathogens compared to other antibiotics. Herein, we found that the antihypertensive drug guanethidine enhanced the activity of rifampicin against certain clinically resistant Gram-negative bacteria, resulting in a reduction of up to 128-fold in the minimum inhibitory concentration. In infected animal models, this combination has achieved treatment benefits, including increased survival and decreased bacterial burden. The antimicrobial mechanism of guanethidine in synergy with rifampicin involves the disruption of the outer membrane of Gram-negative bacteria, leading to dissipation of the proton motive force. This results in an increase in reactive oxygen species and a reduction in ATP synthesis, severely disturbing energy metabolism and ultimately increasing bacterial mortality. In summary, guanethidine has the potential to become a novel adjuvant for rifampicin, offering a new option for the treatment of clinical Gram-negative bacterial infections.

Rapid estimation of DON content in wheat flour using close‐range hyperspectral imaging and machine learning

AbstractFusarium head blight (FHB) is one of the most destructive fungal diseases affecting wheat (Triticum aestivum). Moreover, it is notorious for producing mycotoxin deoxynivalenol (DON), posing a significant global threat to food and feed safety. Traditional methods like enzyme‐linked immunosorbent assay (ELISA) and gas chromatography‐mass spectrometry (GC‐MS) are commonly used to assess DON levels in grain or flour samples and are time‐consuming and expensive. Therefore, a faster, cost‐effective method to estimate DON content is needed, especially for enhancing breeding efforts to reduce DON levels in wheat. In this study, we envisioned integrating close‐range hyperspectral imaging with deep learning (DL) models to estimate DON content in wheat meal/flour. We selected 243 advanced breeding lines from the South Dakota State University (SDSU) wheat breeding program that were evaluated in FHB nurseries (2019–2020 and 2020–2021). The wheat meal samples were analyzed for DON content using GC‐MS and subsequently subjected to close‐range hyperspectral imaging. We evaluated three conventional machine learning (ML), two DL models and data augmentation. Among the conventional ML models, partial least squares regression (PLSR) (with R2P = 0.88 and 0.90 for original and augmented datasets, respectively) demonstrated the highest prediction accuracies for DON content. However, the one‐dimensional convolutional neural network (1D‐CNN) achieved the highest prediction accuracies (R2P = 0.90 and = 0.96 for original and augmented datasets, respectively) compared to all tested models and demonstrated the lowest error. In conclusion, integration of advanced hyperspectral imaging with ML approaches exhibits significant potential for high‐throughput and cost‐effective estimation of DON content in wheat, thereby accelerating wheat breeding efforts for reduced DON levels.

Molecular evidence reveals fish-pathogenic Aphanomyces spp. (Oomycetes: Saprolegniales) on new host of the threatened seasonal cyprinodont fish Nothobranchius spp. (Teleostei: Cyprinodontiformes) in south-eastern Democratic Republic of Congo

The Aphanomyces species pose an important global threat and cause damage to aquaculture and agriculture by infecting aquatic animals and plants. Several subpopulations of the seasonal cyprinodont fish genus Nothobranchius with lesions suggestive of infection with Aphanomyces invadans, were observed in ephemeral wetland habitats of the upper Congo drainage in the south-eastern Democratic Republic of Congo. Molecular analyses on samples collected in 2023 revealed evidence of fish-pathogenic oomycetes Aphanomyces invadans and A. laevis, for the first time in the host of fish genus Nothobranchius spp. All Nothobranchius fishes in the upper Congo drainage are subject to a high level of threat and belong to one of the threatened Red List categories, due to habitat degradation of seasonal wetlands. These fishes complete their seasonal life cycle in ephemeral natural habitats. The latter makes them highly vulnerable, as such wetland habitats are often degraded by the cumulative effect of multiple human stressors which include: the cultivation of wetlands for agriculture, the abstraction of water, the expansion of urban areas and the pollution load. Evidence of infection by oomycete pathogens documented in this study, represents a critical additional threat to the unique seasonal aquatic biodiversity of the region.

The Global Threat from the Irreversible Accumulation of Trifluoroacetic Acid (TFA).

Trifluoroacetic acid (TFA) is a persistent and mobile substance that has been increasing in concentration within diverse environmental media, including rain, soils, human serum, plants, plant-based foods, and drinking water. Currently, TFA concentrations are orders of magnitude higher than those of other per- and polyfluoroalkyl substances (PFAS). This accumulation is due to many PFAS having TFA as a transformation product, including several fluorinated gases (F-gases), pesticides, pharmaceuticals, and industrial chemicals, in addition to direct release of industrially produced TFA. Due to TFA's extreme persistence and ongoing emissions, concentrations are increasing irreversibly. What remains less clear are the thresholds where irreversible effects on local or global scales occur. There are indications from mammalian toxicity studies that TFA is toxic to reproduction and that it exhibits liver toxicity. Ecotoxicity data are scarce, with most data being for aquatic systems; fewer data are available for terrestrial plants, where TFA bioaccumulates most readily. Collectively, these trends imply that TFA meets the criteria of a planetary boundary threat for novel entities because of increasing planetary-scale exposure, where potential irreversible disruptive impacts on vital earth system processes could occur. The rational response to this is to instigate binding actions to reduce the emissions of TFA and its many precursors.

Evaluation of the antibacterial potential of mango (Mangifera indica) seed kernels in Bangladesh

Antimicrobial resistance is a global threat. On the other hand, Bangladesh produces high-quality mangoes, yet the mango coat and seed kernel, which contain medicinal components, remain unused. Therefore, this study investigated the antibacterial potential and toxicity of ethanol extracts from mango (Mangifera indica) seed kernels, which specifically target the bacterial strains Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella sp. Amrapali variant mango seeds were collected, dried, ground into a fine powder, and extracted with ethanol at various ratios. The efficacy of the crude extract was tested via the disc diffusion method. The results demonstrated significant antibacterial activity against gram-positive bacteria (S. aureus and B. cereus), with clear zones of inhibition observed, especially in a dose-dependent manner. The pure crude extract inhibited the growth of S. aureus with a zone of 23 mm, identical to that produced by doxycycline. However, the extract exhibited limited activity against gram-negative bacteria (E. coli and Klebsiella sp.). Additionally, the extract was effective against multidrug-resistant S. aureus. The pure crude extract produced a 22.5 mm zone of inhibition against multidrug-resistant S. aureus, which was slightly smaller than that of gentamicin (23 mm) but larger than those of chloramphenicol (21 mm), vancomycin (20 mm), and tetracycline (16 mm). In vivo toxicity was assessed in mice, revealing no significant adverse effects on the hepatic structure or renal cortex at lower doses (100 μl of pure crude extract). However, higher doses caused mild histopathological changes in the liver and kidneys. These findings suggest that mango seed kernel extract holds promise as an alternative antibacterial agent, particularly against gram-positive and antibiotic-resistant bacteria, while being relatively safe at lower doses. Further research is needed to elucidate the active compounds, mechanisms of action, and broader applications of this extract in combating antibiotic-resistant bacterial infections.

Considerations for prioritising clinical research using bacteriophage.

Antimicrobial resistance (AMR) poses a significant global health threat, as it contributes to prolonged illness, higher mortality rates and increased healthcare costs. As traditional antibiotics become less effective, treatments such as bacteriophage therapy offer potential solutions. The question remains, however, on how to set research priorities in the face of a growing number of antibiotic-resistant pathogens, some common and/or dangerous. One standard way of making decisions about which research to prioritise is by using the disability-adjusted life year metric to estimate the current global impact of a disease or condition, combined with considerations of social justice although decisions made at a national level by governments, especially in low income countries with forecasting potential over future needs may look very different. Another approach is based on the needs of researchers and regulators given what we know about the technology itself. The biological characteristics of bacteriophage therapies set challenges to a universal and standardised prioritisation method. A proof of principle is still arguably needed. With a preliminary discussion of the scope and complexity of AMR and AMR therapeutics, we propose some implications of regulatory frameworks aiming to integrate bacteriophage therapy into mainstream medical practice while gathering scientific data on safety and efficacy, enhancing the collective action needed to combat AMR.

Chemical Space for Peptide-based Antimicrobials.

Multidrug-resistant (MDR) bacteria represent a global public health threat, and antimicrobial peptides (AMPs), derived from naturally occurring linear or cyclic peptides, can provide the solution. However, most AMPs are sensitive to proteases and have poor pharmacokinetics. The EU-funded ERC Advanced Grant SPACE4AMPS aims to identify new AMPs by applying the concepts of chemical space and ligand-based virtual screening, which are well known for small molecule drug discovery, to the world of peptides. We create virtual libraries of peptides and related molecules and use these approaches to select a few tens of compounds for synthesis and detailed. evaluation of antibacterial, toxicity and stability effects. Recent results and prospects of this ongoing project are presented in this review.

Vaccine hesitancy: a structured review from a behavioral perspective (2015–2022)

ABSTRACT Vaccine hesitancy, a complex behavioral phenomenon, poses a significant global health threat and has gained renewed attention amidst the COVID-19 pandemic. This paper scrutinized peer-reviewed literature on vaccine hesitancy published from 2015 to 2022, with a specific focus on behavioral perspectives, utilizing a Theories-Constructs-Variables-Contexts-Methods (TCVCM) framework. The study highlighted prominent theoretical approaches, abstract concepts, research variables, global contexts and academic techniques employed across a selected sample of 138 studies. The result is a consolidated overview of research and schematization of the factors influencing vaccine hesitancy and vaccination behaviors. These include individual-level, contextual, vaccine-specific, organizational, and public-policy-related dynamics. The findings corroborated the complexity of vaccine hesitancy and emphasized the difficulties of pursuing vaccine advocacy. The analysis also identified several directions for future research, and the need to conduct more contextual studies in low- and middle-income nations to bring out the cross-cultural nuances of vaccine hesitancy.

Capturing the complexity of veterinarians' antibiotic prescribing practices in the livestock sector: a meta-ethnography across contexts: Veterinarians' antibiotic prescribing in different contexts.

Strategies and policies to tackle the global public health threat of antimicrobial resistance are increasingly addressing antimicrobial use prescribing practices in both the human and animal health sectors. Veterinarians' antibiotic prescribing practices are influenced by different factors and conditioned by the context within which antibiotic prescribing decisions are made, complexifying the implementation of behaviour change interventions. A better understanding of these factors could therefore help in the design and application of such interventions. Meta-ethnography was used to explore the antibiotic prescribing behaviour of veterinarians in different contexts and to construct a new conceptual framework. A search was conducted in PubMed, Web of Science Core Collection and SciELO Citation Index between 2016 and 2024. The final sample consisted of 29 articles, 27 of which were selected from the 561 articles identified in the search and 2 of which were added by the authors. The results were synthesized and presented through four contextual situations influencing antibiotic prescribing by livestock veterinarians: priorities and pressures, uncertain field conditions, systemic challenges and an enabling environment. The results are presented as a conceptual framework that views veterinarians' antibiotic prescribing behaviour as dynamic, adapting in response to the different contextual situations they encounter. The findings provide an integrated and contextualized understanding of veterinarians' antibiotic prescribing behaviours, which could be implemented to facilitate the development and application of future antimicrobial stewardship interventions.

The clinical praxis of bacteriocins as natural anti-microbial therapeutics.

In recent decades, the excessive use of antibiotics has resulted in a rise in antimicrobial drug resistance (ADR). Annually, a significant number of human lives are lost due to resistant infectious diseases, leading to around 700,000 deaths, and it is estimated that by 2050, there could be up to 10 million casualties. Apart from their possible application as preservatives in the food sector, bacteriocins are gaining acknowledgment as potential clinical treatments. Not only this, these antimicrobial peptides have revealed in modulating the host immune system producing anti-inflammatory and anti-modulatory responses. At the same time, due to the ever-increasing global threat of antibiotic resistance, bacteriocins have gained attraction among researchers due to their potential clinical applications. Bacteriocins as antimicrobial peptides, represent one of the most important natural defense mechanisms among bacterial species, particularly lactic acid bacteria (LAB), that can fight against infection-causing pathogens. In this review, we are highlighting the potential of bacteriocins as novel therapeutics for inhibiting a wide range of clinically relevant and multi-drug-resistant pathogens (MDR). We also highlight the effectiveness and potential applications of current bacteriocin treatments in combating antimicrobial resistance (AMR), thereby promoting human health.

Treatment ineffectiveness towards Haemonchus contortus is highly prevalent in sheep and goat farms of North-Eastern Italy

BackgroundAnthelmintic resistance (AR) is a global threat to grazing livestock farming. In Italy, anthelmintic efficacy remains high compared to other European countries, but many parts of the country haven’t been investigated yet. Local veterinary practitioners from Trentino and Veneto regions reported suspected inefficacy towards anthelmintic drugs in some of their farms, prompting a study on AR in sheep and goat farms of northern Italy. The study aimed to assess anthelmintic effectiveness using genus-specific faecal egg count reduction tests (FECRT), to detect differences in treatment response among nematode genera involved in the infection.ResultsTwelve farms (6 sheep and 6 goat farms) were included based on clinical suspicion of AR. Treatments were carried out with either benzimidazoles (BZ) or macrocyclic lactones (ML) Treatment was effective in 3/6 goat trials, with reduced effectiveness to BZ in two farms and to ML the last one. In sheep farms (6/6), effectiveness was consistently and more severely insufficient. Ineffectiveness was particularly high towards Haemonchus contortus, while Oesophagostomum/Chabertia maintained susceptibility in nearly all trials. Trichostrongylus/Teladorsagia exhibited intermediate results.ConclusionsThis study reveals diminished efficacy of both BZ and ML in small ruminant farms in north-eastern Italy, an area previously lacking data on the topic, except for goats in South Tyrol. Variability in treatment responses among nematode genera support suspicions of AR, and further concerns are raised by the prevalence of treatment ineffectiveness against the highly pathogenic Haemonchus contortus. This finding underscores the urgent need for comprehensive AR monitoring in the area and improved management practices to prevent further resistance development and protect livestock health.

Lichen-associated Fungi Inhabiting from a Mangrove Ecosystem in Sri Lanka: A Novel Source of Antibacterial Agents

The global threat of antimicrobial resistance has spurred interest in discovering innovative antimicrobial agents from diverse sources. Amid the rise of new diseases, the quest for novel drug leads has intensified. This study explores the antibacterial potential of lichen-associated fungi in mangrove ecosystems, using NARA Regional Research Centre in Kalpitiya, Sri Lanka as the study site. Lichen-associated fungi were isolated from collected lichens and the antibacterial activities of the isolates were tested using two gram-positive bacteria: Staphylococcus aureus (ATCC 25923) and Bacillus cereus (ATCC 11778) and two gram-negative bacteria: Pseudomonas aeruginosa (ATCC 25853) and Escherichia coli (ATCC 25922). Putative fungal isolates were primarily screened using agar plug diffusion assay and ethyl acetate extracts of fungal isolates with marked activity were secondarily screened using the well diffusion assay in triplicate. Isolate LIF 0803 identified as Trichosporon faecale showed the most outstanding antibacterial activities as 2.58, 3.43, 4.2, 4.5 cm of zone diameter at 100 mg/mL, and 1.95, 3.08, 3.7, 4.3 cm of zone diameter at 50 mg/mL against P. aeruginosa, S. aureus, B. cereus, and E. coli respectively. All nine fungal isolates showed promising antibacterial activity against both gram-positive and negative bacteria. Therefore, this study showed that lichen-associated fungi in mangrove ecosystems have potent antibacterial activities. Hence, bioassay-guided fractionation of active compounds from lichen-associated fungi and structure elucidation are warranted.

Molecular Characterization and Antibiogram of <i>Pseudomonas aeruginosa</i> Isolated from Fish Sold in Markets of Tirupati, India

Pseudomonas aeruginosa is an emerging opportunistic pathogen and is one of the pathogens in the acronym ESKAPE representing a global threat to human health associated with antimicrobial resistance. The present study aimed for molecular characterization, virulence gene profiling and antimicrobial resistance studies of P. aeruginosa isolated from 200 fish samples collected from different fish markets in Tirupati, Andhra Pradesh, India. Of the 200 fish samples screened, 30.5% were confirmed as P. aeruginosa by PCR, targeting the 16S rRNA gene. Among the positive isolates, it was found that 70.4% and 75.4% of the isolates harbored toxA and exoS virulence markers, respectively. All 61 P. aeruginosa isolates recovered were phenotypically characterized for antimicrobial resistance patterns by the disc diffusion method. The study has found 100% resistance against erythromycin followed by 98.4% resistance to amoxicillin, 91.8% resistance against tetracycline, 88.5% resistance to vancomycin and cotrimoxazole, 45.9% resistance to ciprofloxacin, 44.2% resistance against cefepime and 9.9% resistance to gentamicin. The MAR indices were in the range from 0.5 to 1.0. The prevalence of multiple antibiotic resistance of P. aeruginosa harboringvirulence genes in fish can pose a serious threat and hazard to public health through the consumption of raw or undercooked fish.