Tackling the emerging threat of antifungal resistance to human health

Illuminating antifungal mode of action and resistance with fluorescent probes

The rise in fungal infections, driven by pathogens resistant to the limited scope of antifungal agents available, poses an increasing threat to global health and the economy. Addressing this challenge requires a thorough understanding of the mechanisms of antifungal agents and the development of advanced resistance diagnostic methods. This opinion manuscript highlights recent advancements in antifungal research, with a focus on chemical biology approaches, particularly the development of fluorescent probes derived from various antifungal agents. These probes reveal new aspects of antifungal activity and provide deeper insights into modes of action and resistance mechanisms. Live cell imaging of fungal pathogens labeled with these probes has uncovered novel strategies to enhance antifungal efficacy, understand virulence factors, and detect resistance. These unique small-molecule tools offer powerful new avenues for addressing the fungal infections crisis, harnessing chemical biology approaches to develop innovative solutions to the global challenges posed by fungi.

Unveiling antifungal resistance and biocide tolerance in clinical isolates of Candida spp

AIMS

Candidiasis, caused by Candida spp. is an opportunistic infection with significant healthcare risks, worsened by trends in antifungal resistance. This study aimed to evaluate the antifungal susceptibility profile, investigate resistance mechanisms, assess efflux pump activity, and examine biocide tolerance in clinical Candida isolates.

METHODS

A total of 100 Candida isolates from hospitalized and outpatient individuals were analyzed for their antifungal susceptibility profile, molecular resistance mechanisms through PCR, efflux pump activity with the Cartwheel method, and biocide tolerance (sodium hypochlorite, hydrogen peroxide, and benzalkonium chloride), which was assessed by disk diffusion.

RESULTS

A high prevalence of resistance (87%) to at least one antifungal was observed, with 47.12% of isolates showing simultaneous multiple resistance to three azole derivatives. The highest antifungal agent resistance was observed for fluconazole (n = 70) and the highest susceptibility for amphotericin B (n = 1). The most common mutation was in the ERG11 gene (n = 38/43.7%). Efflux pump activity was detected in both C. albicans and non-albicans Candida species. Biocide testing revealed a higher tolerance for sodium hypochlorite, with an inhibition zone ranging from 18.25 (4.40) to 34.0 (4.00).

CONCLUSIONS

This study highlights significant antifungal resistance in Candida spp. particularly to azoles, stressing the need for improved infection control and novel therapeutic strategies.

Emerging Treatments in Neonatal Fungal Infections: Progress and Prospects

Fungal infections in neonates are potentially life threatening. The differential diagnosis for neonatal rashes is extensive, with common culprits including both bacteria and fungi. Candida albicans is the predominant fungal pathogen, causing infections that range from superficial disease to severe systemic conditions, including sepsis and meningitis. Neonates, especially those who are preterm, are particularly susceptible because of developmentally immature immune systems and the use of invasive procedures and devices in neonatal intensive care units. Congenital cutaneous candidiasis, acquired in utero or during delivery, can lead to disseminated infection with high mortality rates. Early diagnosis and prompt antifungal treatment are crucial but challenging because of subtle clinical presentations, making accurate identification of the offending organism essential for selecting the appropriate treatment. Candida species account for the majority of neonatal fungal infections, with different species necessitating distinct treatments because of varying susceptibility profiles. Aspergillus, another significant pathogen, poses high mortality risks and can present either cutaneously or systemically. Malassezia, though less common, primarily affects preterm infants with catheter-related fungemia. Other fungal species, including Zygomycetes, Trichosporon, and Cryptococcus, rarely produce neonatal infections but are noteworthy for consideration. Treatment of fungal infection is critical despite the relative paucity of information regarding the clinical pharmacology of many antifungal drugs in neonates. We review the major antifungal agents (e.g., amphotericin B, the echinocandins, the azoles) and provide pharmacologic and dosing information. Finally, preventive strategies, including the use of stringent aseptic techniques and careful clinical monitoring, are essential to mitigate both the incidence and severity of these infections in neonates and infants in the first months of life.

A hidden intrinsic ability of bicistronic expression based on a novel translation reinitiation mechanism in yeast

Gene organization in operons and co-expression as polycistronic transcripts is characteristic of prokaryotes. With the evolution of the eukaryotic translation machinery, operon structure and expression of polycistrons were largely abandoned. Whether eukaryotes still possess the ability to express polycistrons, and how they functionally activate bacterial operons acquired by horizontal DNA transfer is unknown. Here, we demonstrate that a polycistron can be rapidly activated in yeast by induction of bicistronic expression under selection. We show that induced translation of the downstream cistron in a bicistronic transcript is based on a novel type of reinitiation mediated by the 80S ribosome and triggered by inefficient stop codon recognition, and that induced bicistronic expression is stable and independent of cis-elements. These results provide key insights into the epigenetic mechanism of the pathway of activation. We also developed a yeast strain that efficiently expresses bicistronic constructs, but does not carry any genomic DNA sequence change, and utilized this strain to synthesize a high-value metabolite from a bicistronic expression construct. Together, our results reveal the capacity of yeast to express bicistrons in a previously unrecognized pathway. While this capacity is normally hidden, it can be rapidly induced by selection to improve fitness.

Indoloquinoline alkaloid neocryptolepine derivative inhibits Botrytis cinerea by targeting thiamine thiazole synthase

The emergence and rapid spread of multidrug-resistant Botrytis cinerea strains pose a great challenge to the quality and safety of agricultural products and the efficient use of pesticides. Previously unidentified fungicides and targets are urgently needed to combat B. cinerea-associated infections as alternative therapeutic options. In this study, the promising compound Z24 demonstrated efficacy against all tested plant pathogenic fungi. Thiamine thiazole synthase (Bcthi4) was identified as a target protein of Z24 by drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR) assays. Molecular docking and enzyme activity experiments have demonstrated that Z24 can affect the function of Bcthi4. Last, mechanistic studies show that Z24 inhibits thiamine biosynthesis by binding to Bcthi4 and induces up-regulation of alternative splicing [alternative 5' splice site (A5SS)] of the Bcthi4 gene. In conclusion, by targeting Bcthi4, Z24 has the potential to be developed as a previously unidentified anti-B. cinerea candidate.

Clinical aspects and recent advances in fungal diseases impacting human health

Fungal diseases are of growing clinical concern in human medicine as the result of changes in the epidemiology, diversity in clinical presentation, emergence of new pathogens, difficulties in diagnosis and increasing resistance to antifungals of current available classes. There is a need for high disease awareness among the public and healthcare physicians, improvement in diagnostic methods and the development of drugs from new therapeutic classes with an improved resistance profile. In this article, we will explore some key aspects of fungal diseases in humans and provide a general overview of this important topic.

Proton-Detected Solid-State NMR for Deciphering Structural Polymorphism and Dynamic Heterogeneity of Cellular Carbohydrates in Pathogenic Fungi

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals fifteen forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan as separate domains or polymers and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of α-1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating soft matrix under antifungal stress. Eight α-1,2-mannan sidechain variants in C. albicans were resolved, highlighting the crucial role of mannan sidechains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

Cyclic N, O-acetals and corresponding opened N, N-aminals as new scaffolds with promising anti-inflammatory and antifungal activities against Candida albicans

P2 × 7R is crucial in the pathogenesis of chronic inflammatory diseases, and its activation leads to the release of pro-inflammatory cytokines, exacerbating the inflammatory response. Two new series of scarce cyclic N, O-acetals (ATF 61-74) and corresponding opened N, N-aminals (CS 1-14) have been designed as novel potential P2RX7 antagonists, then synthesized and evaluated for their anti-inflammatory properties through investigating the pro-inflammatory markers and also for their antifungal activity against Candida albicans. Three compounds (ATF 64, CS 8, and CS 9) exhibited dual antifungal and anti-inflammatory properties. ATF 64, CS 8, and CS 9 reduced ROS production and IL-1β expression in macrophages and intestinal cells in a manner correlated with NF-KB expression. These compounds showed excellent antifungal activity against clinical isolates of C. albicans resistant to fluconazole and caspofungin, and reduced C. albicans biofilm formation. Treatment with CS 8 or CS 9 protected the nematode Caenorhabditis elegans against infection with C. albicans and enhanced antimicrobial gene expression. This duality of action offers a promising new pharmacological strategy to counteract inflammatory diseases and propels N, N-aminals as promising candidates for future optimization and investigation.

Fungal microbiota in COPD patients during exacerbations

Acute exacerbations of chronic obstructive pulmonary disease (COPD) results in increased mortality and can be triggered by a range of factors, including microorganisms. Very little studies have examined the role of fungi and fungal diversity in COPD patients. The aim of the study was to determine the role of Candida in COPD during an exacerbation. Oral swabs, sputum, feces and whole blood samples were collected from the AECOPD patients and control group. Mycological and serological analysis were performed. Yeast were statistically significantly more often isolated from the AECOPD group (97.06%) than from the control group (26.32%). 7 species were isolated from the AECOPD, and 3 from the control group. Dominated Candida albicans followed by C. tropicalis. α-diversity was much greater in AECOPD patients than in controls. β-diversity was also assessed. A much higher level of antimycotic resistance was observed in isolates from the AECOPD group, which affects the effectiveness of therapy. Serological tests showed twice the frequency of positive results in the AECOPD group. The mycobiota of AECOPD patients is numerically and taxonomically richer than controls, including species less frequently recorded in humans. Our research confirms that fungal mycobiota may be a potential factor influencing the development of exacerbations and progression of COPD.

Antifungal Action of Valencene and Nootkatone Compounds in Association with Fluconazole and Their Mechanism of Action Against Candida spp. and Pichia kudriavzevii Strains

Candidemia is a public health challenge as it causes thousands of annual deaths and combating it has become difficult due to the development of resistance in Candida spp. Compounds derived from natural products may counter this resistance. Therefore, we evaluate the intrinsic and combined antifungal activity of valencene and nootkatone compounds and their possible mechanism of action against Candida spp. Using the microdilution method, the antifungal effect of sesquiterpenes and their combination with fluconazole was determined. The results comprised the yeast growth curve and its 50% Inhibitory Concentration (IC50). They showed that the compounds alone inhibited microbial growth at a concentration of 1024 µg/mL for valencene being able to kill the fungus Pichia kudriavzevii (Candida krusei), for nootkatone the inhibition occurred at 512 µg/mL and was able to kill the species P. kudriavzevii and Candida tropicalis. Combined with the antifungal, the inhibition occurred at low concentrations (2 and 4 µg/mL) against all strains except P. kudriavzevii, which the combination with nootkatone inhibited at 512 µg/mL. The IC50 revealed inhibition of the strains at higher concentrations in the compounds and fluconazole alone compared to the combination concentrations. In addition, both compounds acted through the production of reactive oxygen species, helping the antifungal against C. albicans and P. kudriavzevii, contributing minimally to compromising membrane viability. Thus, the compounds show promise for combined activity with fluconazole.

Structure-guided optimization of small molecules targeting Yck2 as a strategy to combat Candida albicans

Candida albicans is the most common cause of life-threatening fungal infection in the developed world but remains a therapeutic challenge. Protein kinases have been rewarding drug targets across diverse indications but remain untapped for antifungal development. Previously, screening kinase inhibitors against C. albicans revealed a 2,3-aryl-pyrazolopyridine, GW461484A (GW), which targets casein kinase 1 (CK1) family member Yck2. Here, we report optimization of GW via two complementary approaches, synthesis of bioisosteres possessing an imidazo[1,2-a]pyridine core, and R-group substitution of GW's pyrazolo[1,5-a]pyridine core. Characterization of compounds reveals two 6-cyano derivatives with improved pharmacological properties that retain whole-cell bioactivity and selectivity for fungal Yck2 compared to human CK1α. Efficacy studies in mice indicate both analogs possess single-agent activity against C. albicans resistant to first-line echinocandin antifungals and potentiate non-curative echinocandin treatment. Results validate Yck2 as an antifungal target and encourage further development of inhibitors acting by this previously unexploited mode of action.

Electrically-driven drug delivery into deep cutaneous tissue by conductive microneedles for fungal infection eradication and protective immunity

Fungal infections affect over 13 million people worldwide and are responsible for 1.5 million deaths annually. Some deep cutaneous fungal infections may extend the dermal barriers to cause systemic infection, resulting in substantial morbidity and mortality. However, the management of deep cutaneous fungal infection is challenging and yet overlooked by traditional treatments, which only offer limited drug availability within deep tissue. In this study, we have developed an electrically stimulated microneedle patch to deliver miconazole into the subcutaneous layer. We tested its antifungal efficacy using in vitro and ex vivo models that mimic fungal infection. Moreover, we confirmed its anti-fungal and wound-healing effects in a murine subcutaneous fungal infection model. Furthermore, our findings also showed that the combination of miconazole and applied current synergistically stimulated the nociceptive sensory nerves, thereby activating protective cutaneous immunity mediated by dermal dendritic and γδ-T cells. Collectively, this study provides a new strategy for minimally invasive delivery of therapeutic agents and the modulation of the neuro-immune axis in deep tissue.

Vidarabine as a novel antifungal agent against Candida albicans: insights on mechanism of action

Around 1.5 million mortality cases due to fungal infection are reported annually, posing a massive threat to global health. However, the effectiveness of current antifungal therapies in the treatment of invasive fungal infections is limited. Repurposing existing antifungal drugs is an advisable alternative approach for enhancing their effectiveness. This study evaluated the antifungal efficacy of the antiviral drug vidarabine against Candida albicans ATCC 90028. Antifungal susceptibility testing was performed by microbroth dilution assay and further processed to find the minimum fungicidal concentration. Investigation on probable mode of vidarabine action against C. albicans was assessed by using the ergosterol reduction assay, reactive oxygen species (ROS) accumulation, nuclear condensation, and apoptosis assay. Results revealed that C. albicans was susceptible to vidarabine action and exhibited minimum inhibitory concentration at 150 µg/ml. At a concentration of 300 µg/ml, vidarabine had fungicidal activity against C. albicans. 300 µg/ml vidarabine-treated C. albicans cells demonstrated 91% reduced ergosterol content. Annexin/FITC/PI assay showed that vidarabine (150 µg/ml) had increased late apoptotic cells up to 31%. As per the fractional inhibitory concentration index, vidarabine had synergistic activity with fluconazole and caspofungin against this fungus. The mechanism underlying fungicidal action of vidarabine was evaluated at the intracellular level, and probably because of increased nuclear condensation, enhanced ROS generation, and cell cycle arrest. In conclusion, this data is the first to report that vidarabine has potential to be used as a repurposed antifungal agent alone or in combination with standard antifungal drugs, and could be a quick and safe addition to existing therapies for treating fungal infections.

Aspergillus-mediated allergic airway inflammation is triggered by dendritic cell recognition of a defined spore morphotype

BACKGROUND

Exposure to fungi, especially Aspergillus fumigatus, can elicit potent allergic inflammation that triggers and worsens asthmatic disease. Dendritic cells (DCs) initiate allergic inflammatory responses to allergic stimuli. However, it is unclear if Af spores during isotropic growth (early spore swelling) can activate DCs to initiate allergic responses or if germination is required. This lack of basic understanding of how Af causes disease is a barrier to developing new treatments.

OBJECTIVE

We sought to show that a precise Af morphotype stage during spore swelling can trigger DCs to mediate allergic inflammatory responses and ascertain if antifungal therapeutics can be effective at suppressing this process.

METHODS

We used an Af strain deficient in pyrimidine biosynthesis (ΔpyrG) to generate populations of Af spores arrested at different stages of isotropic growth (swelling) via temporal removal of uracil and uridine from growth media. These arrested spore stages were cultured with bone marrow-derived DCs (BMDCs), and their activation was measured via flow cytometry and ELISA to examine which growth stage was able to activate BMDCs. These BMDCs were then adoptively transferred into the airways to assess if they were able to mediate allergic inflammation in naïve recipient mice. Allergic airway inflammation in vivo was determined via flow cytometry, ELISA, and real-time quantitative PCR. This system was also used to determine if antifungal drug (itraconazole) treatment could alter early stages of spore swelling and therefore BMDC activation and in vivo allergic inflammation upon adoptive transfer.

RESULTS

We found that Af isotropic growth is essential to trigger BMDC activation and mediate allergic airway inflammation. Furthermore, using time-arrested Af stages, we found that at least 3 hours in growth media enabled spores to swell sufficiently to activate BMDCs to elicit allergic airway inflammation in vivo. Incubation of germinating Af with itraconazole reduced spore swelling and partially reduced their ability to activate BMDCs to elicit in vivo allergic airway inflammation.

CONCLUSION

Our results have pinpointed the precise stage of Af development when germinating spores are able to activate DCs to mediate downstream allergic airway inflammation. Furthermore, we have identified that antifungal therapeutics partially reduced the potential of Af spores to stimulate allergic responses, highlighting a potential mechanism by which antifungal treatment might help prevent the development of fungal allergy.

A comprehensive insight into naphthalimides as novel structural skeleton of multitargeting promising antibiotics

The globally growing antimicrobial resistance seriously threatens human health, increasing efforts have been devoting to the development of novel antibiotics. Naphthalimides contain a special skeleton of cyclic double imides and the naphthalene framework, this unique structure can exert multitargeting abilities which are helpful to overcome the escalating issue of resistance. Therefore, research in connection with the development of naphthalimides as novel antimicrobial agents is becoming progressively active. It has been revealed that naphthalimides as novel structural skeleton of multitargeting promising antibiotics could not only target DNAs and enzymes, disturb membrane, produce reactive oxygen species, etc. suggesting the multitargeting actions which do not induce resistance, but also show a broad antimicrobial spectrum with safety profile and pharmacokinetic characteristics, implying large potential as a new type of antibiotics via continuous efforts toward antimicrobial naphthalimides. This review presents naphthalimides as a new type of potential antimicrobial agents and discusses rational design strategies, structure-activity relationships, and mechanisms of action, with a comprehensive view to providing a new insight for in the rational design of efficient, broad-spectrum, and low-toxic naphthalimide antibiotics.

Species-specific circular RNA circDS-1 enhances adaptive evolution in Talaromyces marneffei through regulation of dimorphic transition

Thermal adaptability is a crucial characteristic for mammalian pathogenic fungi that originally inhabit natural ecosystems. Thermally dimorphic fungi have evolved a unique ability to respond to host body temperature by shifting from mycelia to yeast. The high similarity of protein-coding genes between these fungi and their relatives suggests the indispensable but often overlooked roles of non-coding elements in fungal thermal adaptation. Here, we systematically delineated the landscape of full-length circRNAs in both mycelial and yeast conditions of Talaromyces marneffei, a typical thermally dimorphic fungus causing fatal Talaromycosis, by optimizing an integrative pipeline for circRNA detection utilizing next- and third-generation sequencing. We found T. marneffei circRNA demonstrated features such as shorter length, lower abundance, and circularization-biased splicing. We then identified and validated that circDS-1, independent of its parental gene, promotes the hyphae-to-yeast transition, maintains yeast morphology, and is involved in virulence regulation. Further analysis and experiments among Talaromyces confirmed that the generation of circDS-1 is driven by a T. marneffei-specific region in the flanking intron of circDS-1. Together, our findings not only provide fresh insights into the role of circRNA in fungal thermal adaptation but also reveal a novel molecular mechanism for the adaptive evolution of functional circRNAs derived from intronic mutations.

Genomics insights of candidiasis: mechanisms of pathogenicity and drug resistance

Candidiasis, a prevalent class of human infections caused by fungi belonging to the Candida genus, is garnering increasing attention due to its pathogenicity and the emergence of drug resistance. The advancement of genomics technologies has offered powerful tools for investigating the pathogenic mechanisms and drug resistance characteristics of Candida. This comprehensive review provides an overview of the applications of genomics in candidiasis research, encompassing genome sequencing, comparative genomics, and functional genomics, along with the pathogenic features and core virulence factors of Candida. Moreover, this review highlights the role of genomic variations in the emergence of drug resistance, further elucidating the evolutionary and adaptive mechanisms of Candida. In conclusion, the review underscores the current state of research and prospective avenues for exploration of candidiasis, providing a theoretical basis for clinical treatments and public health strategies.

In Vitro Study to Evaluate the Best Conditions Highlighting the Antimicrobial Activity of Carum carvi Essential Oil on Human Pathogen Isolates in Formulations Against the Spread of Antibiotic Resistance

Background/Objectives: In recent years, antimicrobial resistance has become a major threat to global health, and scientific research aiming to identify new therapeutic resources is a priority. Essential oils (EOs), obtained from spices belonging to the culinary tradition, like Carum carvi essential oil (CC-EO), are of great interest for their antimicrobial activity, but the methods used to evaluate their efficacy need to be standardized. The aims of this work were to evaluate the following: (i) the best microbiological in vitro test; (ii) the best surfactant; and (iii) the best microbiological target of CC-EO and its method of administration. Methods: CC-EO quality was evaluated using gas chromatography-mass spectrometry. Antimicrobial susceptibility testing with drugs currently in use was performed. Antimicrobial effectiveness against 70 clinical strains belonging to S. aureus, E. coli, E. faecalis, K. pneumoniae, P. aeruginosa, S. pyogenes, and C. albicans was evaluated. Two microbial tests (broth microdilution tests and disk diffusion), generally used in routine clinical practice, were compared. To choose the best vehicle, Tween80, DMSO, and ethanol were evaluated. The antimicrobial efficacy of vapors was assessed using a microatmosphere test. Results: The broth microdilution test is confirmed as the best in evaluating the antimicrobial activity of EOs. The most suitable EOs vehicle for antimicrobial testing was Tween80. CC-EO and its vapors were effective against GRAM+ and C. albicans strains, both sensible and resistant, and ineffective against GRAM-. Conclusions: In the future, it may be possible to include CC-EO in topical or spray formulations for the treatment of GRAM+ and C. albicans infections.

The antimicrobial activity of ETD151 defensin is dictated by the presence of glycosphingolipids in the targeted organisms

Fungal infections represent a significant global health concern, with a growing prevalence of antifungal drug resistance. Targeting glucosylceramides (GlcCer), which are functionally important glycosphingolipids (GSL) present in fungal membranes, represents a promising strategy for the development of antifungal drugs. GlcCer are associated with the antifungal activity of certain plant and insect defensins. The 44-residue ETD151 peptide, optimized from butterfly defensins, is active against several fungal pathogens. ETD151 has been shown to induce a multifaceted mechanism of action (MOA) in Botrytis cinerea, a multiresistant phytopathogenic fungus. However, the target has yet to be identified. Our findings demonstrate that the presence of GlcCer in membranes determines the susceptibility of Pichia pastoris and Candida albicans toward ETD151. To ascertain whether this is due to direct molecular recognition, we demonstrate that ETD151 selectively recognizes liposomes containing GlcCer from B. cinerea, which reveals a methylated-sphingoid base structure. The dissociation constant was estimated by microscale thermophoresis to be in the µM range. Finally, fluorescence microscopy revealed that ETD151 localizes preferentially at the surface of B. cinerea. Furthermore, the majority of prokaryotic cells do not contain GSL, which explains their resistance to ETD151. We investigated the susceptibility of Novosphingobium capsulatum, one of the rare GSL-containing bacteria, to ETD151. ETD151 demonstrated transient morphological changes and inhibitory growth activity (IC50 ~75 µM) with an affinity for the cell surface, emphasizing the critical importance of GSL as target. Understanding the MOA of ETD151 could pave the way for new perspectives in human health and crop protection.

Kodamaea ohmeri: An emergent yeast from a One Health perspective

Kodamaea ohmeri is an emerging and opportunistic yeast associated with a high mortality rate in humans. As it is commonly found in the environment, it is possible that environmental conditions and agricultural practices contribute to the adaptation of this yeast and the selection of antifungal resistance. During a multicentric study in Brazil, conducted under a One Health perspective, 14 isolates of K. ohmeri were identified from different sources: three from blood cultures, three from animals (swine and poultry), and eight from animal environments (swine and poultry). Yeasts were isolated using CHROmagar® Candida medium and identified by MALDI-TOF MS and ITS rDNA barcoding. Minimum inhibitory concentration (MIC) was determined using the broth microdilution method for clinical (azoles, echinocandins, pyrimidine analogs, and polyenes), and environmental antifungals (tebuconazole, pyraclostrobin, carbendazim, and mancozeb), and hospital disinfectants (quaternary ammonium compounds). Of note, color variations of K. ohmeri were noted on CHROmagar® depending on the incubation time, which is likely to complicate its identification. Following polyphasic identification and taxonomic confirmation, all isolates demonstrated low MIC values for clinical antifungals, disinfectants, and tebuconazole. However, all isolates were able to grow in the presence of carbendazim, mancozeb, and pyraclostrobin. Together, these findings highlight the risks associated with the use of environmental azoles, such as tebuconazole, as they may impact non-target fungi of medical importance, but other fungicides do not present the same risk. This is the first study to demonstrate that K. ohmeri, an important emerging yeast in human medicine, can be isolated from various sources, including patients. Although the isolates exhibited low MIC values for clinical antifungals, it is crucial to monitor changes in sensitivity patterns over time in emerging microorganisms to prevent the development of multidrug resistance, which may originate in the environment.

Prodrugging fungicidal amphotericin B significantly decreases its toxic effects

Amphotericin B (AmB) is one of the most effective antifungal drugs, with a strong, dose-dependent activity against most Candida and Aspergillus species responsible for life-threatening infections. However, AmB is severely toxic, which hinders its broad use. In this proof-of-concept study, we demonstrate that prodrugging AmB considerably decreases AmB toxicity without affecting its fungicidal activity. For this purpose, we modified the AmB structure by attaching a designer phosphate promoiety, thereby switching off its mode of action and preventing its toxic effects. The original fungicidal activity of AmB was then restored upon prodrug activation by host plasma enzymes. These AmB prodrugs showed a safer toxicity profile than commercial AmB deoxycholate in Candida and Aspergillus species and significantly prolonged larval survival of infected Galleria mellonella larvae. Based on these findings, prodrugging toxic antifungals may be a viable strategy for broadening the antifungal arsenal, opening up opportunities for targeted prodrug design.

Broad-Spectrum Activity and Mechanisms of Action of SQ109 on a Variety of Fungi

We investigated the activity of the tuberculosis drug SQ109 against sixteen fungal pathogens: Candida albicans, C. auris, C. glabrata, C. guilliermondi, C. kefyr, C. krusei, C. lusitaniae, Candida parapsilosis, C. tropicalis, Cryptococcus neoformans, Rhizopus spp., Mucor spp., Fusarium spp., Coccidioides spp., Histoplasma capsulatum and Aspergillus fumigatus. MIC values varied widely (125 ng/mL to >64 μg/mL) but in many cases we found promising (MIC~4 μg/mL) activity as well as MFC/MIC ratios of ~2. SQ109 metabolites were inactive. The activity of 12 analogs of SQ109 against Saccharomyces cerevisiae correlated with protonophore uncoupling activity, suggesting mitochondrial targeting, consistent with the observation that growth inhibition was rescued by agents which inhibit ROS species accumulation. SQ109 disrupted H+/Ca2+ homeostasis in S. cerevisiae vacuoles, and there was synergy (FICI~0.31) with pitavastatin, indicating involvement of isoprenoid biosynthesis pathway inhibition. SQ109 is, therefore, a potential antifungal agent with multi-target activity.

A microscopy-based image analysis pipeline for the quantification of germination of filamentous fungi

Germination is the fundamental process whereby fungi transition from the dormant and stress resistant spores into actively replicating cells such as hyphae. Germination is essential for fungal colonization of new environments and pathogenesis, yet this differentiation process remains relatively poorly understood. For filamentous fungi, the study of germination has been limited by the lack of high-throughput, temporal, low cost, and easy-to-use methods of quantifying germination. To this end we have developed an image analysis pipeline to automate the quantification of germination from microscopy images. We have optimized this tool for the fungal pathogen Aspergillus fumigatus and demonstrated its potential applications by evaluating different strains, germination inhibitors, and auxotrophic and antifungal resistant mutants. Finally, we have expanded this tool to a variety of filamentous fungi and developed an easy-to-use web app for the fungal research community.

Investigating the effectiveness of atorvastatin mouthwash on denture stomatitis: A randomized, double-blind controlled trial

STATEMENT OF PROBLEM

Denture stomatitis (DS) is a common oral disorder in patients with complete maxillary dentures. Typical treatments such as nystatin or azoles lead to drug resistance after a long period. Several studies have shown the antifungal activity of statins against Candida albicans; however, studies on the antifungal effect of atorvastatin against DS are lacking.

PURPOSE

The purpose of this randomized, double-blind controlled trial was to assess the effectiveness of atorvastatin mouthwash against DS.

MATERIAL AND METHODS

Twenty-two participants diagnosed with DS were randomly allocated into 2 groups: 11 in the intervention group (atorvastatin mouthwash) and 11 in the control group (nystatin). Participants were asked to use the mouthwash 3 times a day for 2 weeks. The length and width of the lesions were measured, and the number of colonies were counted on days 1 and 14. Data were analyzed with the Spearman correlation coefficient and the Mann-Whitney, Kruskal Wallis, and Wilcoxon tests (α=.05).

RESULTS

The number of colonies before and after using a mouthwash was significantly different in the control and intervention groups (P=.005 and P=.003, respectively). The number of colonies in the 2 groups were statistically similar on the first day (P=.809). However, a significant difference was observed between the groups on day 14 (P=.024). The number of colonies in the atorvastatin group decreased more than nystatin, indicating that atorvastatin was more effective. A significant difference among the groups was found in terms of Candida species detected after the intervention (P=.032).

CONCLUSIONS

Atorvastatin was effective in reducing Candida species in participants with DS and can be used as an antifungal agent in treating DS.

Antifungal stewardship in the UK: where are we now?

Background

Antifungal stewardship (AFS) is the judicious use of today's antifungal agents with the aim of improving patient outcomes and preserving their future effectiveness. Antifungal resistance (AFR) is increasing globally, with more patients at risk of Invasive Fungal Disease (IFD), highlighting the urgent need to standardize AFS practices in the UK. The aim of this position paper is to understand the current AFS landscape in the UK.

Methods

A virtual panel discussion was held from September to October 2023 on an online platform followed by a virtual meeting with nine healthcare professionals from across the UK selected for their expertise on IFD management and AFS. The discussion was structured across four topics: current AFS landscape, key elements of an AFS programme, diagnostics and diagnostic stewardship, and unmet needs in education and training. A thematic analysis was carried out. The results represent the collated and summarized views from these activities.

Results and discussion

Participants reported barriers to implementing AFS and its integration within antimicrobial stewardship (AMS) programmes in the UK. The primary challenge identified was a lack of resources, including funding and staff time. Sub-optimal fungal diagnostics and limited mycology expertise was reported as a barrier to AFS, clinical IFD and AFR surveillance. Approaches to combatting these challenges may include investing in formal mycology networks to serve as centres of clinical expertise and diagnostic hubs.

Conclusion

National standards for AFS services and associated outcome metrics need to be established to set a benchmark for centres to improve AFS.

Potable water as a source of intermediate and borderline-resistant Aspergillus and Candida strains

The World Health Organization calls to assess possible health risks from emerging fungi originating not only from hospitals but also from the natural environment. Fungal contamination in oligotrophic water systems represents a public health concern due to the potential for the emergence of antifungal-resistant strains. This study focused on the identification of Aspergillus spp. and Candida spp. isolated from different water sources and materials in contact with water. Isolated strains have been tested against nine antifungals to assess the prevalence of resistance in these strains. Only one strain of Aspergillus protuberus was resistant to amphotericin B. On the other hand, all Candida strains were intermediately resistant to anidulafungin and micafungin, 5.8% were borderline resistant to 5-flucytosine and fluconazole, and 3% to voriconazole. Candida parapsilosis sensu stricto isolated from water samples had statistically higher minimal inhibitory concentration (MIC) for anidulafungin than clinical strains and clinical strains had statistically higher MIC for itraconazole. Statistical analysis pointed out habitat to be significant for higher MIC in C. parapsilosis. Our findings show that borderline-resistant strains can be transferred by water; thus, potable water should be considered as a possible source of resistant strains in hospitals and healthcare units.

Small Disulfide Proteins with Antifungal Impact: NMR Experimental Structures as Compared to Models of Alphafold Versions

In response to the growth of emerging resistance to conventional antifungal drugs, antifungal proteins (AFPs) of filamentous Ascomycetes origin have been discovered in recent years. Understanding the structure of AFPs is crucial for elucidating their antifungal mechanisms and developing new therapeutic agents. While nuclear magnetic resonance (NMR) has proven effective in determining the structures of small proteins, some AFP structures remain unresolved, necessitating the use of alternative prediction methods. Through bioinformatics analysis and heatmaps of amino acid sequence identity and similarity matrix, we categorized AFPs into three major classes and six subcategories, revealing structural and bioactivity differences. We employed AlphaFold (AF) to predict the 3D structures of six different AFPs, with predictions compared to NMR-derived structures. The results demonstrated a high degree of consistency between AF and NMR structures, with AF excelling in structural quality assessment and accurately capturing complex disulfide bond patterns. Both AF2 and AF3 models outperform the NMR model in overall structural quality and coherence, with AF3 showing the best performance. However, the limitations of AF should be considered, including its reduced accuracy in predicting multi-metal ion complexes, suboptimal performance in highly flexible or disordered regions, and its inability to account for multiple conformers, as it generates only a single dominant structure. Moreover, while AF3 accurately predicts all disulfide bond patterns, AF2 falls short in this regard. This study verifies the reliability of AF in the structural prediction of cysteine-rich AFPs while highlighting these constraints, offering important support for the rational design of new protein-based antifungal drugs.

Anti-Candida albicans effect and mechanism of Pachysandra axillaris Franch

ETHNOPHARMACOLOGICAL RELEVANCE

Pachysandra axillaris Franch., a traditional herbal medicine in Yunnan, has been used to treat traumatic injuries and stomach ailments, some of which were related to microbial infections in conventional applications, but, to the best of our knowledge, the antifungal bioactivity of this plant and its main antifungal components have not been previously reported.

AIM OF THE STUDY

To identify the antifungal compounds of P. axillaris against fluconazole-resistant C. albicans in vitro and in vivo, and then elucidate the underlying mechanism of action.

MATERIALS AND METHODS

The antifungal compounds were obtained by bioguided isolation, and then they were investigated in vitro by MIC, growth curves, time-kill assay, and drug resistance induction. The antifungal mechanism was explored using combined network pharmacology and metabolomic analysis, and further supported by analyzing sterol composition using LC-MS/MS, scanning and transmission electron microscopy observation of fungal cell morphology, examining its effects on cell membranes using the fluorescent probes and RT-qPCR. Additionally, the antifungal effect in vivo was evaluated by a murine C. albicans skin infection model.

RESULTS

Three bioactive compounds from P. axillaris efficiently inhibited fluconazole-resistant C. albicans (MIC = 4 μg/mL), in which the major compound, pachysamine M, affected the ergosterol biosynthesis pathway by inhibiting ERG genes (ERG1, ERG4, ERG7, ERG9, and ERG24), leading to the accumulation of squalene, lanosterol, and zymosterol. So, pachysamine M targeted cell membranes in vitro by reducing the ergosterol level, to avoid drug resistance. In addition, it promoted wound healing, reduced fungal load, and alleviated inflammation in vivo.

CONCLUSIONS

Pachysamine M, an antifungal compound without reported before, inhibited fluconazole-resistant C. albicans efficiently in vitro and in vivo, and its mechanism targeted cell membranes, reducing the risk of drug resistance, which validated the traditional use of P. axillaris for the treatment of fungal skin infections.

Enhanced biocidal efficacy of alcohol based disinfectants with salt additives

Surfaces contaminated with pathogens pose a significant risk of disease transmission and infection. Alcohol-based disinfectants are widely utilized to decontaminate high-touch areas across various settings. However, their limited antimicrobial activity and the emergence of alcohol-tolerant strains necessitate the development of highly efficient disinfectant formulations. In this work we test the broad-spectrum antimicrobial activities of the salt-incorporated alcohol solution disinfectant against enveloped and non-enveloped viruses, spore-forming and non-spore-forming bacteria, and mold and yeast fungi. Specifically, the disinfection capability of the isopropanol (IPA) and ethanol (EtOH) solutions containing NaCl salts was evaluated by measuring (1) antibacterial activity against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli), and an alcohol-tolerant strain of E. coli; (2) sporicidal activity against Clostridioides difficile; (3) the antiviral activity against enveloped A/PR8/34 H1N1 influenza virus and non-enveloped adenovirus VR-5; and (4) the antifungal efficacy against Aspergillus niger and Cryptococcus neoformans from the time-dependent viability assays. Additionally, the biocidal activity of the disinfectant formulation was tested by spraying it on the biocontaminated surfaces, including plastics, stainless steel, and glass. Overall, the inclusion of salt in alcohol solutions significantly enhanced their disinfection activities, positioning these solutions as promising candidates for long-term disinfection and maintenance of hygienic environments. This method, which employs mild salt instead of toxic materials, offers a simpler, more cost-effective, and safer alternative to conventional alcohol-based disinfectants. This research is expected to significantly impact on disease prevention and contribute greatly to public health and safety.

Targeted regulation of sterol biosynthesis genes according to perturbations in ergosterol biosynthesis in fungi

INTRODUCTION

The synthesis and regulation of ergosterol are vital for fungal growth and stress adaptation. While ergosterol-mediated feedback regulation is a recognized mechanism controlling sterol biosynthesis in fungi, prior research suggests the presence of additional regulatory mechanisms. However, the specifics of the alternative regulatory mechanisms have not been systematically investigated.

OBJECTIVES

We proposed that a regulatory network is likely to discern disturbances in sterol biosynthesis and trigger responses accordingly. This study aimed to validate the hypothesis and investigate the regulatory mechanisms.

METHODS

Quantitative Real-time PCR and HPLC-MS/MS were used to explore and compare the regulation of sterol biosynthesis in different fungi. Key transcription factors involved in the alternative regulatory mechanism in Neurospora crassa were identified by phenotypic profiling of a transcription factor mutant library. ChIP-qPCR, fluorescence confocal imaging, RNA sequencing, and gene set enrichment analysis (GSEA) were used to reveal the mechanism of each transcription factor.

RESULTS

Unlike the canonical ergosterol-mediated feedback regulation in fungi like C. neoformans, our study demonstrated that the inhibitions of ergosterol biosynthesis at specific steps triggered distinct transcriptional responses of erg genes in fungi, including N. crassa and Aspergillus fumigatus. In N. crassa, the responses were orchestrated by different transcription factors. Specifically, the inhibition of ERG24 and ERG2 activated transcription factors SAH-2 and AtrR, resulting in the upregulation of erg24, erg2, erg25, and erg3. Furthermore, the inhibition of ERG11/CYP51 activated transcription factor NcSR, leading to the upregulation of erg11 and erg6. Phenotypic profiles of mutants of various N. crassa erg genes and the aforementioned transcription factors implied that the targeted regulation of ergosterol biosynthesis could fortify fungal viability within complex habitats.

CONCLUSION

Our study reveals a novel regulatory mechanism in fungi: targeted upregulation of specific sterol biosynthesis genes in response to given perturbations in ergosterol biosynthesis, exhibiting a higher degree of precision and sophistication in sterol biosynthesis regulation.

Electrical signaling in fungi: past and present challenges

Electrical signaling is a fundamental mechanism for integrating environmental stimuli and coordinating responses in living organisms. While extensively studied in animals and plants, the role of electrical signaling in fungi remains a largely underexplored field. Early studies suggested that filamentous fungi generate action potential-like signals and electrical currents at hyphal tips, yet their function in intracellular communication remained unclear. Renewed interest in fungal electrical activity has fueled developments such as the hypothesis that mycorrhizal networks facilitate electrical communication between plants and the emerging field of fungal-based electronic materials. Given their continuous plasma membrane, specialized septal pores, and insulating cell wall structures, filamentous fungi possess architectural features that could support electrical signaling over long distances. However, studying electrical phenomena in fungal networks presents unique challenges due to the microscopic dimensions of hyphae, the structural complexity of highly modular mycelial networks, and the limitations of traditional electrophysiological methods. This review synthesizes current evidence for electrical signaling in filamentous fungi, evaluates methodological approaches, and highlights experimental challenges. By addressing these challenges and identifying best practices, we aim to advance research in this field and provide a foundation for future studies exploring the role of electrical signaling in fungal biology.

The impact of phenotypic heterogeneity on fungal pathogenicity and drug resistance

Phenotypic heterogeneity in genetically clonal populations facilitates cellular adaptation to adverse environmental conditions while enabling a return to the basal physiological state. It also plays a crucial role in pathogenicity and the acquisition of drug resistance in unicellular organisms and cancer cells, yet the exact contributing factors remain elusive. In this review, we outline the current state of understanding concerning the contribution of phenotypic heterogeneity to fungal pathogenesis and antifungal drug resistance.

The evolution of antifungal therapy: Traditional agents, current challenges and future perspectives

Fungal infections kill more than 3 million people every year. This high number reflects the significant challenges that treating these diseases worldwide presents. The current arsenal of antifungal drugs is limited and often accompanied by high toxicity to patients, elevated treatment costs, increased frequency of resistance rates, and the emergence of naturally resistant species. These treatment challenges highlight the urgency of developing new antifungal therapies, which could positively impact millions of lives each year globally. Our review offers an overview of the antifungal drugs currently available for treatment, presents the status of new antifungal drugs under clinical study, and explores ahead to future candidates that aim to help address this important global health issue.

Candida glabrata: A Tale of Stealth and Endurance

Candida (Nakaseomyces) glabrata, an opportunistic human fungal pathogen, causes mucosal and deep-seated infections in immunocompromised individuals. Recently designated as a high-priority fungal pathogen by the World Health Organization (WHO), C. glabrata exhibits low inherent susceptibility to azole antifungals. In addition, about 10% clinical isolates of C. glabrata display co-resistance to both azole and echinocandin drugs. Molecular mechanisms of antifungal resistance and virulence in C. glabrata are currently being delineated in-depth. This Review provides an overview of the epidemiology, biology, drug resistance, tools and host model systems for C. glabrata. Additionally, we discuss the immune evasion strategies that aid C. glabrata in establishing infections in the host. Overall, this Review aims to contribute to ongoing efforts to raise awareness of human pathogenic fungi, the growing threat of antifungal drug resistance and the unmet need for novel antifungal therapies, with an ultimate goal of improving clinical outcomes of affected individuals.

Metal-organic frameworks as thermocatalysts for hydrogen peroxide generation and environmental antibacterial applications

Reactive oxygen species (ROS) are highly reactive, making them useful for environmental and health applications. Traditionally, photocatalysts and piezocatalysts have been used to generate ROS, but their utilization is limited by various environmental and physical constraints. This study introduces metal-organic frameworks (MOFs) as modern thermocatalysts efficiently producing hydrogen peroxide (H2O2) from small temperature differences. Temperature fluctuations, abundant in daily life, offer tremendous potential for practical thermocatalytic applications. As proof of concept, MOF materials coated onto carbon fiber fabric (MOF@CFF) created a thermocatalytic antibacterial filter. The study compared three different MOFs (CuBDC, MOF-303, and ZIF-8) with bismuth telluride (Bi2Te3), a known thermocatalytic material. ZIF-8 demonstrated superior H2O2 generation under low-temperature differences, achieving 96% antibacterial activity through temperature variation cycles. This work advances potential in thermoelectric applications of MOFs, enabling real-time purification and disinfection through H2O2 generation. The findings open interdisciplinary avenues for leveraging thermoelectric effects in catalysis and various technologies.

Structure-guided optimization of small molecules targeting the yeast casein kinase, Yck2, as a therapeutic strategy to combat Candida albicans

Candida albicans is the most common cause of life-threatening fungal infection in the developed world but remains a therapeutic challenge. Protein kinases have been rewarding drug targets across diverse indications but remain untapped for antifungal development. Previously, screening kinase inhibitors against C. albicans revealed a 2,3-aryl-pyrazolopyridine, GW461484A (GW), which targets casein kinase 1 (CK1) family member Yck2. Here, we report optimization of GW via two complementary approaches, synthesis of bioisosteres possessing an imidazo[1,2-a]pyridine core, and R-group substitution of GW's pyrazolo[1,5-a]pyridine core. Characterization of compounds synthesized revealed two 6-cyano derivatives with improved pharmacological properties that retained whole-cell bioactivity and selectivity for fungal Yck2 compared to human CK1α. Efficacy studies in mice indicated both analogs possess single-agent activity against C. albicans resistant to first-line echinocandin antifungals and potentiate non-curative echinocandin treatment. Results validate Yck2 as an antifungal target and encourage further development of inhibitors acting by this previously unexploited mode of action.

Exploring the antifungal potential of Cannabis sativa-derived stilbenoids and cannabinoids against novel targets through in silico protein interaction profiling

Cannabinoid and stilbenoid compounds derived from Cannabis sativa were screened against eight specific fungal protein targets to identify potential antifungal agents. The proteins investigated included Glycosylphosphatidylinositol (GPI), Enolase, Mannitol-2-dehydrogenase, GMP synthase, Dihydroorotate dehydrogenase (DHODH), Heat shock protein 90 homolog (Hsp90), Chitin Synthase 2 (CaChs2), and Mannitol-1-phosphate 5-dehydrogenase (M1P5DH), all of which play crucial roles in fungal survival and pathogenicity. This research evaluates the binding affinities and interaction profiles of selected cannabinoids and stilbenoids with these eight proteins using molecular docking and molecular dynamics simulations. The ligands with the highest binding affinities were identified, and their pharmacokinetic profiles were analyzed using ADMET analysis. The results indicate that GMP synthase exhibited the highest binding affinity with Cannabistilbene I (-9.1 kcal/mol), suggesting hydrophobic solid interactions and multiple hydrogen bonds. Similarly, Chitin Synthase 2 demonstrated significant binding with Cannabistilbene I (-9.1 kcal/mol). In contrast, ligands such as Cannabinolic acid and 8-hydroxycannabinolic acid exhibited moderate binding affinities, underscoring the variability in interaction strengths among different proteins. Despite promising in silico results, experimental validation is necessary to confirm therapeutic potential. This research lays a crucial foundation for future studies, emphasizing the importance of evaluating binding affinities, pharmacokinetic properties, and multi-target interactions to identify promising antifungal agents.

The role of gene copy number variation in antimicrobial resistance in human fungal pathogens

Faced with the burden of increasing resistance to antifungals in many fungal pathogens and the constant emergence of new drug-resistant strains, it is essential to assess the importance of various resistance mechanisms. Fungi have relatively plastic genomes and can tolerate genomic copy number variation (CNV) caused by aneuploidy and gene amplification or deletion. In many cases, these genomic changes lead to adaptation to stressful conditions, including those caused by antifungal drugs. Here, we specifically examine the contribution of CNVs to antifungal resistance. We undertook a thorough literature search, collecting reports of antifungal resistance caused by a CNV, and classifying the examples of CNV-conferred resistance into four main mechanisms. We find that in human fungal pathogens, there is little evidence that gene copy number plays a major role in the emergence of antifungal resistance compared to other types of mutations. We discuss why we might be underestimating their importance and new approaches being used to study them.

PHI-base - the multi-species pathogen-host interaction database in 2025

The Pathogen-Host Interactions Database (PHI-base) has, since 2005, provided manually curated genes from fungal, bacterial and protist pathogens that have been experimentally verified to have important pathogenicity, virulence and/or effector functions during different types of interactions involving human, animal, plant, invertebrate and fungal hosts. PHI-base provides phenotypic annotation and genotypic information for both native and model host interactions, including gene alterations that do not alter the phenotype of the interaction. In this article, we describe major updates to PHI-base. The latest version of PHI-base, 4.17, contains a 19% increase in genes and a 23% increase in interactions relative to version 4.12 (released September 2022). We also describe the unification of data in PHI-base 4 with the data curated from a new curation workflow (PHI-Canto), which forms the first complete release of PHI-base version 5.0. Additionally, we describe adding support for the Frictionless Data framework to PHI-base 4 datasets, new ways of sharing interaction data with the Ensembl database, an analysis of the conserved orthologous genes in PHI-base, and the increasing variety of research studies that make use of PHI-base. PHI-base version 4.17 is freely available at www.phi-base.org and PHI-base version 5.0 is freely available at phi5.phi-base.org.

Efficacy of cleaning, disinfection, and sterilization modalities for addressing infectious drug-resistant fungi: a review

This is a timely and important review that focuses on the appropriateness of established cleaning, disinfection, and sterilization methods to safely and effectively address infectious fungal drug-resistant pathogens that can potentially contaminate reusable medical devices used in healthcare environment in order to mitigate the risk of patient infection. The release of the World Health Organization (WHO) fungal priority pathogen list (FPPL) in 2022 highlighted the public health crisis of antimicrobial resistance (AMR) in clinically relevant fungal species. Contamination of medical devices with drug-resistant fungal pathogens (including those on the FPPL) in healthcare is a rare event that is more likely to occur due to cross-transmission arising from lapses in hand hygiene practices. Established disinfection and sterilization methods decontaminate fungal pathogens on single-use and reusable medical devices; however, there are assumptions that reusable devices destined for semi-critical use are appropriately cleaned and do not harbour biofilms that may undermine the ability to effectively decontamination these type devices in healthcare. International standards dictate that manufacturer's instructions for use must provide appropriate guidance to healthcare facilities to meet safe reprocessing expectations that include addressing drug-resistant fungal pathogens. Increased environmental monitoring and vigilance surrounding fungal pathogens in healthcare is advised, including adherence to hand hygiene/aseptic practices and appropriate cleaning encompassing the simplification of reusable device features for 'ease-of-reach'. There are emereging opportunities to promote a more integrated multiactor hub approach to addressing these sophisticated challenges, including future use of artificial intelligence and machine learning for improved diagnostics, monitoring/surveillance (such as healthcare and wastewater-based epidemiology), sterility assurance, and device design. There is a knowledge gap surrounding the occurrence and potential persistence of drug-resistant fungal pathogens harboured in biofilms, particularly for ascertaining efficacy of high-level disinfection for semi-critical use devices.

Azole Antifungal Consumption in Community Pharmacy Sales in Mainland Portugal: Trend Analysis from 2014 to 2023

Background/Objectives: Excessive or inadequate use of antimicrobial drugs may lead to the emergence of resistant strains. For this reason, it is important to monitor consumption indicators to assess drugs' utilization over time. This study aimed to analyze the consumption of medically prescribed azole antifungal drugs in mainland Portugal from 2014 to 2023, focusing on those directed to genital infections: fluconazole, isoconazole, itraconazole, and sertaconazole. Methods: For each drug, the evaluated parameters were the total number of packages, number of packages per 1000 inhabitants, defined daily dose (DDD) per 1000 inhabitants per day, and total costs. For this purpose, we used data from community pharmacies' sales, which are available through INFARMED (the Portuguese national authority on medicines and health products). Results: Several trends emerged from data analysis. The COVID-19 pandemic negatively affected the consumption of all azole antifungal drugs included in this study. However, after 2020, fluconazole and sertaconazole consumption has been increasing. In the specific case of fluconazole, there was an increase in expenditure, although the total number of packages suffered a decrease over the 10-year study period. Additionally, the defined daily dose (DDD) per 1000 inhabitants per day for fluconazole and itraconazole was lower compared to estimates from the last available survey (2009). Conclusions: Although our findings represent a lesser pressure on fungi, further monitoring is needed to better understand the evolution of fluconazole and itraconazole consumption over time, particularly due to the trends observed in this study.

In search of herbistasis: COT-metsulfuron methyl displays rare herbistatic properties

Weed management is an essential intervention for maintaining food security and protecting biodiversity but is heavily reliant on chemical control measures (i.e., herbicides). Concerningly, only one herbicide has been developed with a new mode of action (MOA) since the 1980s. Therefore, alternative strategies for preventing weed growth need to be explored. The lesser-known concept of halting weed growth through herbistasis could be one strategy to alleviate the lack of success in obtaining new MOA leads, but this type of activity has rarely been investigated. Herein reported is a bioisosteric cyclooctatetraene (COT) for phenyl ring replacement tactic, using the commercial acetolactate synthase (ALS) inhibitor metsulfuron methyl, that has unearthed a rare agent displaying herbistatic properties against the weed, Cryptostegia grandiflora (rubber vine).

Role of Posaconazole Drug in the Treatment of Invasive Fungal Disease: A Review

Posaconazole is an antifungal medication used primarily to treat invasive fungal infections caused by various organisms, such as Aspergillus, Candida, and certain molds. It belongs to the class of drugs known as triazole antifungals. Clinical studies have reported posaconazole to be effective in treating various invasive fungal infections, especially in patients who are immunocompromised, such as those with weakened immune systems due to conditions like HIV/AIDS, undergoing chemotherapy, or having received an organ transplant. It has effectively treated invasive candidiasis, aspergillosis, zygomycosis, and other serious fungal infections. The effectiveness of the drug varies based on factors, such as the type of infection, the patient's immune status, and the site of infection. This review describes the types of infection, the drug's safety profile, the development of resistance to posaconazole, and strategies to manage or prevent resistance.

Insights into phosphatidic acid phosphatase and its potential role as a therapeutic target

Phosphatidic acid phosphatase, a conserved eukaryotic enzyme that catalyzes the Mg2+-dependent dephosphorylation of phosphatidic acid to produce diacylglycerol, has emerged as a vital regulator of lipid homeostasis. By controlling the balance of phosphatidic acid and diacylglycerol, the enzyme governs the use of the lipids for synthesis of the storage lipid triacylglycerol and the membrane phospholipids needed for cell growth. The mutational, biochemical, and cellular analyses of yeast phosphatidic acid phosphatase have provided insights into the structural determinants of enzyme function with the understanding of its regulation by phosphorylation and dephosphorylation. The key role that the enzyme plays in triacylglycerol synthesis indicates it may be a potential drug target to ameliorate obesity in humans. The enzyme activity, which is critical to the growth and virulence of pathogenic fungi, is a proposed target for therapeutic development to ameliorate fungal infections.

Environmental microbiome, human fungal pathogens, and antimicrobial resistance

Traditionally, antifungal resistance (AFR) has received much less attention compared with bacterial resistance to antibiotics. However, global changes, pandemics, and emerging new fungal infections have highlighted global health consequences of AFR. The recent report of the World Health Organisation (WHO) has identified fungal priority pathogens, and recognised AFR among the greatest global health threats. This is particularly important given the significant increase in fungal infections linked to climate change and pandemics. Environmental factors play critical roles in AFR and fungal infections, as many clinically relevant fungal pathogens and AFR originate from the environment (mainly soil). In addition, the environment serves as a potential rich source for the discovery of new antifungal agents, including mycoviruses and bacterial probiotics, which hold promise for effective therapies. In this article, we summarise the environmental pathways of AFR development and spread among high priority fungal pathogens, and propose potential mechanisms of AFR development and spread. We identify a research priority list to address key knowledge gaps in our understanding of environmental AFR. Further, we propose an integrated roadmap for predictive risk management of AFR that is critical for effective surveillance and forecasting of public health outcomes under current and future climatic conditions.

What in Earth? Analyses of Canadian soil populations of Aspergillus fumigatus

Aspergillus fumigatus is a globally distributed mold and a major cause of opportunistic infections in humans. Because most infections are from environmental exposure, it is critical to understand environmental populations of A. fumigatus. Soil is a major ecological niche for A. fumigatus. Here, we analyzed 748 soil isolates from 21 locations in six provinces and one territory in Canada. All isolates were genotyped using nine microsatellite markers. Due to small sample size and/or close proximities for some local samples, these isolates were grouped into 16 local geographic and ecological populations. Our results indicated high allelic and genotypic diversities within most local and provincial populations. Interestingly, low but statistically significant genetic differentiations were found among geographic populations within Canada, with relatively similar proportions of strains and genotypes belonging to two large genetic clusters. In Hamilton, Ontario, and Vancouver, BC, where two and three ecological populations were analyzed, respectively, we found limited genetic difference among them. Most local and provincial populations showed evidence of both clonality and recombination, with no population showing random recombination. Of the 748 soil isolates analyzed here, two were resistant to triazole antifungals. We discuss the implications of our results to the evolution and epidemiology of A. fumigatus.

The antidepressant drug sertraline is a novel inhibitor of yeast Pah1 and human lipin 1 phosphatidic acid phosphatases

Phosphatidic acid phosphatase (PAP) is an evolutionarily conserved eukaryotic enzyme that catalyzes the Mg2+-dependent dephosphorylation of phosphatidic acid to produce diacylglycerol. The product and substrate of PAP are key intermediates in the synthesis of triacylglycerol and membrane phospholipids. PAP activity is associated with lipid-based cellular defects indicating the enzyme is an important target for regulation. We identified that the antidepressant sertraline is a novel inhibitor of PAP. Using Saccharomyces cerevisiae Pah1 as a model PAP, sertraline inhibited the activity by a noncompetitive mechanism. Sertraline also inhibited the PAP activity of human lipin 1 (α, β, and γ), an orthologue of Pah1. The inhibitor constants of sertraline for the S. cerevisiae and human PAP enzymes were 7-fold and ∼2-fold, respectively, lower than those of propranolol, a commonly used PAP inhibitor. Consistent with the inhibitory mechanism of sertraline and propranolol, molecular docking of the inhibitors predicts that they interact with non-catalytic residues in the haloacid dehalogenase-like catalytic domain of Pah1. The Pah1-CC (catalytic core) variant, which lacks regulatory sequences, was inhibited by both drugs in accordance with molecular docking data. That Pah1 is a physiological target of sertraline in S. cerevisiae is supported by the observations that the overexpression of PAH1 rescued the sertraline-mediated inhibition of pah1Δ mutant cell growth, the lethal effect of overexpressing Pah1-CC was rescued by sertraline supplementation, and that a sublethal dose of the drug resulted in a 2-fold decrease in TAG content.