Environmental microbiome, human fungal pathogens, and antimicrobial resistance

Current advancements and future perspectives of 1,2,3-triazoles to target lanosterol 14α-demethylase (CYP51), a cytochrome P450 enzyme: A computational approach

Antifungal resistance has become a significant challenge, necessitating the development of novel antifungal agents. Resistance often arises from prolonged and widespread use of existing treatments, leading to mutations in fungal enzymes that reduce drug efficacy. Amongst various scaffolds, 1,2,3-triazoles have emerged as antifungal agents due to their ability to bind effectively to fungal enzymes. This review examines the binding interactions of 1,2,3-triazoles with lanosterol 14α-demethylase (CYP51), an enzyme in Candida albicans (PDB IDs:5TZ1and5V5Z), highlighting their potential in fighting resistance. The CYP51 family is a captivating topic to investigate the structural and functional roles of P450 and makes for a key medical focus. It is one of crucial step in biosynthesis of sterol in eukaryotes. Antifungals mostly work on CYP51 and could also be used to treat protozoan diseases in the future. 1,2,3-Triazoles exert their antifungal effects by inhibiting the CYP51 enzyme, which is crucial for ergosterol synthesis in fungal cell membranes thereby leading to disruption of membrane integrity and ultimately leads to death of fungal cell. In silico studies like molecular docking and molecular dynamics (MD) simulations, reveal that these compounds establish strong interactions (e.g., π-π, π-alkyl, CH, hydrogen bonding, and Van der Waals interactions) with active site residues, stabilizing the ligand-enzyme complex. This review of virtual screening assays shows the adaptability of the 1,2,3-triazole scaffold and its widespread use in core antifungal compounds, making it a key pharmacophore for new lead development against resistant fungal species.

Earthworms Significantly Alter the Composition, Diversity, Abundance and Pathogen Load of Fungal Communities in Sewage Sludge from Different Urban Wastewater Treatment Plants

Management of sewage sludge is of ongoing concern because this waste product is generated continuously and contains high levels of harmful constituents. Among these constituents, fungal pathogens are of increasing concern. Vermicomposting can reduce the amounts of bacterial pathogens in sewage sludge; however, information about the effects of earthworms on fungal pathogens is limited or non-existent. We therefore aimed to determine whether vermicomposting can control fungal pathogens present in sewage sludge. Using next-generation sequencing techniques, we characterized fungal communities in sewage sludge from eight wastewater treatment plants (WWTPs) and in casts (feces) of earthworms feeding on sewage sludge. Fungal communities in earthworm casts primarily included taxa that were absent from sewage sludges, indicating a significant change in fungal composition. Changes in fungal diversity depended on the source of sewage sludge (WWTP). All of the sewage sludges contained low levels of fungal pathogens, most of which were significantly reduced or eliminated by earthworms, such as Armillaria, Cystobasidium, Exophiala and Ophiosthoma. Moreover, earthworm gut transit enhanced beneficial (saprotrophic) fungi like Arthrobotrys, Aseroe, Crepidotus and Trichurus. Overall, digestion of sewage sludge by earthworms alone generated a mainly pathogen-free fungal community with a high proportion of saprotrophic taxa, which would enhance nutrient cycling rates.

Plant pathogens, microbiomes, and soil health

Healthy soil is vital for ecosystem sustainability and global food security. However, anthropogenic activities that promote intensive agriculture, landscape and biodiversity homogenization, and climate change disrupt soil health. The soil microbiome is a critical component of healthy soils, and increasing evidence suggests that soils with low diversity or homogenized microbial systems are more susceptible to soil pathogen invasion, but the extent and mechanisms that increase the threat of pathogen invasion (i.e., increase in prevalence of existing species and introduction of new species) remain unclear. This article aims to fill this knowledge gap by synthesizing the literature and providing novel insights for the scientific community and policy advisors. We also present the current and future global distribution of some dominant soil-borne pathogens. We argue that an improved understanding of the interplay between the soil microbiome, soil health, host, and pathogen distribution, and their responses to environmental changes is urgently needed to ensure the future of productive farms, safe food, sustainable environments, and holistic global well-being.

Emergence of Triazole-Resistant Cryptococcus neoformans after Exposure to Environmentally Relevant Concentrations of Difenoconazole in Liquid Medium and Soil

The rapid global emergence and spread of resistance to clinical triazoles in Cryptococcus neoformans have been associated with the use of agricultural triazole fungicides. However, there is no direct evidence currently linking the emergence of triazole-resistant C. neoformans (TRCN) strains to the application of triazole fungicides in soil. This study investigated whether triazole resistance in C. neoformans could be induced by difenoconazole, an agricultural triazole fungicide, in liquid medium and soil. Our findings reveal that environmentally relevant concentrations of difenoconazole can drive cross-resistance to clinical triazoles in C. neoformans through the upregulation of ERG11 and efflux pump genes (AFR1, AFR3, and MDR1). Notably, the prevalence of TRCN strains in soil correlates with residual difenoconazole levels, with significantly more TRCN isolates observed at two- and five-fold the recommended dose than at the standard dose. These results provide direct evidence linking agricultural triazole use to the emergence of TRCN and highlight the importance of applying difenoconazole at or below the recommended dosage to mitigate resistance development in soil environments. This study addresses a critical gap in the understanding of the environmental drivers of triazole resistance and underscores the need for responsible fungicide use to prevent the spread of resistant pathogens.

Effects of fluconazole and amphotericin B in the control of cryptococcal pneumonia in vivo

Cryptococcal pneumonia is a severe fungal infection of the respiratory system, predominantly caused by Cryptococcus neoformans. Its incidence is increasing, driven by evolving pathogen dynamics and heightened susceptibility among patient populations. This investigation aimed to assess the combined therapeutic efficacy of Fluconazole and Amphotericin B for cryptococcal pneumonia and to explore the roles of miR-15b and TGF-β1 in modulating treatment response. Twenty-eight patients diagnosed with cryptococcal pneumonia were randomly allocated to receive either Amphotericin B monotherapy (control group) or a combination of Amphotericin B and Fluconazole (observation group) over a 14-day period. Key respiratory function indices-forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratios-were measured pre- and post-treatment, alongside levels of procalcitonin (PCT), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), miR-15b, and TGF-β1. Results demonstrated marked improvements in pulmonary function within the observation group, with significantly higher FEV1, FVC, and FEV1/FVC values than those in the control group (P < 0.05). Additionally, the observation group exhibited greater reductions in PCT and sTREM-1, coupled with notable elevations in miR-15b and TGF-β1 levels. The combination therapy achieved a total response rate of 92.86%, significantly surpassing the control's 57.14% efficacy (P < 0.05). These findings indicate that Fluconazole combined with Amphotericin B not only enhances clinical efficacy by mitigating inflammation but also supports lung function recovery with a favourable safety profile, highlighting its utility in managing cryptococcal pneumonia effectively.

Antimicrobial peptides and proteins against drug-resistant pathogens

The rise of drug-resistant pathogens, driven by the misuse and overuse of antibiotics, has created a formidable challenge for global public health. Antimicrobial peptides and proteins have garnered considerable attention as promising candidates for novel antimicrobial agents. These bioactive molecules, whether derived from natural sources, designed synthetically, or predicted using artificial intelligence, can induce lethal effects on pathogens by targeting key microbial structures or functional components, such as cell membranes, cell walls, biofilms, and intracellular components. Additionally, they may enhance overall immune defenses by modulating innate or adaptive immune responses in the host. Of course, development of antimicrobial peptides and proteins also face some limitations, including high toxicity, lack of selectivity, insufficient stability, and potential immunogenicity. Despite these challenges, they remain a valuable resource in the fight against drug-resistant pathogens. Future research should focus on overcoming these limitations to fully realize the therapeutic potential of antimicrobial peptides in the infection control.