Siderophore-Conjugated Antifungals: A Strategy to Potentially Cure Fungal Infections.

Fungi pose a global threat to humankind due to the increasing emergence of multi-drug-resistant fungi. There is a rising incidence of invasive fungal infections. Due to the structural complexity of fungal cell membranes, only a few classes of antifungal agents are effective and have been approved by the U.S. FDA. Hence, researchers globally are focusing on developing novel strategies to cure fungal infections. One of the potential strategies is the "Trojan horse" approach, which uses the siderophore-mediated iron acquisition (SIA) system to scavenge iron to deliver potent antifungal agents for therapeutics and diagnostics. These siderophore conjugates chelate to iron and are taken up through siderophore-iron transporters, which are overexpressed exclusively on microbes such as bacteria or fungi, but not mammalian cells. Our comprehensive review delves into recent advancements in the design of siderophore-conjugated antifungal agents to gain fungal cell entry. Notably, our focus extends to unraveling the intricate relationship between the structure of natural siderophores or siderophore-like molecules and the resulting antifungal activity. By exploring these design strategies, we aim to contribute to the ongoing discourse on combating drug-resistant fungal infections and advancing the landscape of antifungal theranostics.

Bridging fungal resistance and plant growth through constitutive overexpression of Thchit42 gene in Pelargonium graveolens.

KEY MESSAGE: Thchit42 constitutive expression for fungal resistance showed synchronisation with leaf augmentation and transcriptome analysis revealed the Longifolia and Zinc finger RICESLEEPER gene is responsible for plant growth and development. Pelargonium graveolens essential oil possesses significant attributes, known for perfumery and aromatherapy. However, optimal yield and propagation are predominantly hindered by biotic stress. All biotechnological approaches have yet to prove effective in addressing fungal resistance. The current study developed transgenic geranium bridging molecular mechanism of fungal resistance and plant growth by introducing cassette 35S::Thchit42. Furthermore, 120 independently putative transformed explants were regenerated on kanamycin fortified medium. Primarily transgenic lines were demonstrated peak pathogenicity and antifungal activity against formidable Colletotrichum gloeosporioides and Fusarium oxysporum. Additionally, phenotypic analysis revealed ~ 2fold increase in leaf size and ~ 2.1fold enhanced oil content. To elucidate the molecular mechanisms for genotypic cause, de novo transcriptional profiles were analyzed to indicate that the auxin-regulated longifolia gene is accountable for augmentation in leaf size, and zinc finger (ZF) RICESLEEPER attributes growth upregulation. Collectively, data provides valuable insights into unravelling the mechanism of Thchit42-mediated crosstalk between morphological and chemical alteration in transgenic plants. This knowledge might create novel opportunities to cultivate fungal-resistant geranium throughout all seasons to fulfil demand.

Mechanisms of antifungal resistance and developments in alternative strategies to combat Candida albicans infection.

Candida albicans is a commensal fungus that infects the humans and becomes an opportunistic pathogen particularly in immuno-compromised patients. Among the Candida genus, yeast C. albicans is the most frequently incriminated species and is responsible for nearly 50-90% of human candidiasis, with vulvovaginal candidiasis alone, affecting about 75% of the women worldwide. One of the significant virulence traits in C. albicans is its tendency to alternate between the yeast and hyphae morphotypes, accounting for the development of multi-drug resistance in them. Thus, a thorough comprehension of the decision points and genes controlling this transition is necessary, to understand the pathogenicity of this, naturally occurring, pernicious fungus. Additionally, the formation of C. albicans biofilm is yet another pathogenesis trait and a paramount cause of invasive candidiasis. Since 1980 and in 90 s, wide spread use of immune-suppressing therapies and over prescription of fluconazole, a drug used to treat chronic fungal infections, triggered the emergence of novel anti-fungal drug development. Thus, this review thoroughly elucidates the diseases associated with C. albicans infection as well as the anti-fungal resistance mechanism associated with them and identifies the emerging therapeutic agents, along with a rigorous discussion regarding the future strategies that can possibly be adopted for the cure of this deleterious pathogen.

Transcriptome profile of pecan scab resistant and susceptible trees from a pecan provenance collection.

Pecan scab is a devastating disease that causes damage to pecan (Carya illinoinensis (Wangenh.) K. Koch) fruit and leaves. The disease is caused by the fungus Venturia effusa (G. Winter) and the main management practice for controlling the disease is by application of fungicides at 2-to-3-week intervals throughout the growing season. Besides disease-related yield loss, application of fungicides can result in considerable cost and increases the likelihood of fungicide resistance developing in the pathogen. Resistant cultivars are available for pecan growers; although, in several cases resistance has been overcome as the pathogen adapts to infect resistant hosts. Despite the importance of host resistance in scab management, there is little information regarding the molecular basis of genetic resistance to pecan scab.The purpose of this study was to elucidate mechanisms of natural pecan scab resistance by analyzing transcripts that are differentially expressed in pecan leaf samples from scab resistant and susceptible trees. The leaf samples were collected from trees in a provenance collection orchard that represents the natural range of pecan in the US and Mexico. Trees in the orchard have been exposed to natural scab infections since planting in 1989, and scab ratings were collected over three seasons. Based on this data, ten susceptible trees and ten resistant trees were selected for analysis. RNA-seq data was collected and analyzed for diseased and non-diseased parts of susceptible trees as well as for resistant trees. A total of 313 genes were found to be differentially expressed when comparing resistant and susceptible trees without disease. For susceptible samples showing scab symptoms, 1,454 genes were identified as differentially expressed compared to non-diseased susceptible samples. Many genes involved in pathogen recognition, defense responses, and signal transduction were up-regulated in diseased samples of susceptible trees, whereas differentially expressed genes in pecan scab resistant samples were generally down-regulated compared to non-diseased susceptible samples.Our results provide the first account of candidate genes involved in resistance/susceptibility to pecan scab under natural conditions in a pecan orchard. This information can be used to aid pecan breeding programs and development of biotechnology-based approaches for generating pecan cultivars with more durable scab resistance.

Combination oral antifungal therapy for paediatric fungal infection: An option to improve efficacy and overcome clinical resistance.

There is increasing evidence of clinically resistant cutaneous fungal infections. The use of combination oral antifungals is described in adults but not in paediatric patients. We present seven paediatric cases of clinically resistant fungal infections treated successfully with combination oral antifungal therapy after inadequate response to a single agent.

Pdr5: A master of asymmetry.

Pdr5 is a founding member of a large (pdr) subfamily of clinically and agriculturally significant fungal ABC transporters. The tremendous power of yeast genetics combined with biochemical and structural approaches revealed the astonishing asymmetry of this efflux pump. Asymmetry is manifested in Pdr5's ATP-binding sites, drug binding sites, signal transformation interface, and molecular exit gate. Even its mode of conformational switching is asymmetric with one half of the protein remaining nearly stationary. In the case of its ATP-binding sites, asymmetry is created by replacing a set of highly conserved residues with a characteristic set of deviant ones. This contrasts with the asymmetry of the molecular gate. There, a full complement of canonical residues is present, but structural features in the vicinity prevent some of these from forming a molecular plug during closure. Compared to their canonical-functioning counterparts, the deviant ATP site and these gating residues have different, essential functions. In addition to its remarkable asymmetry, the surprising observation that Pdr5 is a drug / proton co-transporter shines a new light on this remarkable protein.

Improving health literacy of antifungal use-Comparison of the readability of antifungal medicines information from Australia, EU, UK, and US of 16 antifungal agents across 5 classes (allylamines, azoles, echinocandins, polyenes, and others).

Adherence to antifungals is poor in high endemic regions where antifungal resistance is high. Poor readability of prescription/over-the-counter (OTC) antifungals may contribute to poor adherence, due to the patient not fully understanding the purpose, importance, and dosage of their antifungal medicine. As there are no reports on the readability of antifungals, this study examined the readability of patient-facing antifungal information. Antifungals (n = 16; five classes [allylamines, azoles, echinocandins, polyenes, and others-flucytosine and griseofulvin]) were selected. Readability of four sources of information, (i) summary of product characteristics, (ii) patient information leaflets (PILs), (iii) OTC patient information, and (iv) patient web-based information, was calculated using Readable software, to obtain readability scores [(i) Flesch Reading Ease [FRE], (ii) Flesch-Kinkaid Grade Level [FKGL], (iii) Gunning Fog Index, and (iv) Simple Measure of Gobbledygook (SMOG) Index) and text metrics [word count, sentence count, words/sentence, and syllables/word]. PILs, web-based resources, and OTC patient information had good readability (FRE mean ± sd = 52.8 ± 6.7, 58.6 ± 6.9, and 57.3 ± 7.4, respectively), just falling short of the ≥ 60 target. For FKGL (target ≤ 8.0), PILs, web-based resources, and OTC patient information also had good readability (mean ± sd = 8.5 ± 1.0, 7.2 ± 0.86, and 7.8 ± 0.1, respectively). Improved readability scores observed correlate with reduced words, words/sentence and syllables/word. Improving readability may lead to improved patient health literacy. Healthcare professionals, academics, and publishers preparing written materials regarding antifungals for the lay/patient community are encouraged to employ readability calculators to check the readability of their work, so that the final material is within recommended readability reference parameters, to support the health literacy of their patients/readers.

Yeast and mould infections can be difficult-to-treat, due to resistance. Our study shows that patient information on antifungals is fairly easy-to-read. Such information helps the patient know how best to take the medicine and help avoid resistance. Authors should always try to write clearly for patients.

MALDI-TOF MS: A Quick Method to Detect the Susceptibility of Fusarium spp. Clinical Isolates to Amphotericin B.

Disseminated fusariosis is treated with amphotericin B and voriconazole. To determine adequate therapy, the minimal inhibitory concentration (MIC) is used. However, MIC analysis is based on visual observation and requires a long period of fungal incubation. The measure of the minimal profile change concentration (MPCC) using MALDI-TOF MS is a quick spectral method that has presented good results in determining the antimicrobial resistance of yeasts. However, there is a lack of information on filamentous fungi. In the present work, 13 Fusarium spp. clinical isolates and two reference strains were used. MIC was obtained according to the M38-A2 protocol of the Clinical Laboratory Standards Institute, while MPPC was obtained following the initial steps of the M38-A2 protocol. Both Biotyper and the Rstudio environment were used to analyze mass spectra. For some fungal strains, the data obtained from the software MALDI Biotyper Compass 4.1 led to fuzzy heatmaps resulting in difficult interpretation, while heatmaps obtained using Rstudio tools generated better MPCC resolutions. Herein, 86.6% of the AMB MPCC values were highly correlated with the gold-standard AMB MIC. MALDI-TOF MS is a prominent tool used to determine MPCCs quicker, cost-effectively, and more accurately for Fusarium spp. strains. However, better statistical analyses could help measure the technique's limit detection.

Vulvovaginal Candidiasis in Pregnancy-Between Sensitivity and Resistance to Antimycotics.

Vulvovaginitis with Candida spp. is the most common infection in women and the rate is increased during pregnancy. Antifungal prescription in pregnant women continues to present challenges and the decision must balance the risk of fetal toxicity with the benefits to the fetus and mother. Starting from the idea that clotrimazole is the most recommended antifungal in candidal vaginitis in pregnancy, we tested the sensitivity of different species of Candida spp. to other azoles, polyenes, and antimetabolites. This retrospective study (January to June 2019) assessed 663 pregnant women hospitalized for various pregnancy-related symptoms in which samples of phage secretion were taken. The laboratory results confirmed 21% of cases, indicating 140 positive mycologic samples. In this study, vaginal candidiasis was mostly related to the first trimester of pregnancy (53.57%,) and less related in the last trimester (17.14%). Candida albicans was the most frequent isolated strain in this study, accounting for 118 cases, followed by 16 strains of Candida glabrata and 6 cases of Candida krusei. The highest sensitivity for C. albicans was found in azoles, mostly in miconazole (93.2%), while C. krusei was completely resistant to polyene with low sensitivity in antimetabolites and even in some azoles, such as fluconazole. In our study, higher resistance rates to flucytosine were found, with C. glabrata and C. krusei exhibiting greater resistance than C. albicans.

Intestinal bacteria-a powerful weapon for fungal infections treatment.

The morbidity and mortality of invasive fungal infections are rising gradually. In recent years, fungi have quietly evolved stronger defense capabilities and increased resistance to antibiotics, posing huge challenges to maintaining physical health. Therefore, developing new drugs and strategies to combat these invasive fungi is crucial. There are a large number of microorganisms in the intestinal tract of mammals, collectively referred to as intestinal microbiota. At the same time, these native microorganisms co-evolve with their hosts in symbiotic relationship. Recent researches have shown that some probiotics and intestinal symbiotic bacteria can inhibit the invasion and colonization of fungi. In this paper, we review the mechanism of some intestinal bacteria affecting the growth and invasion of fungi by targeting the virulence factors, quorum sensing system, secreting active metabolites or regulating the host anti-fungal immune response, so as to provide new strategies for resisting invasive fungal infection.

Antifungal Properties of Hydrazine-Based Compounds against Candida albicans.

Candida albicans, an opportunistic yeast, is the most common cause of fungal infection. In the past decade, there has been an increase in C. albicans resistance to existing antifungal drugs, which has necessitated the development of new antifungal agents. In the present study, screening 60 compounds from the JUNIA chemical library enabled us to explore an additional 11 hybrid compounds that contain pyrrolidinone rings and hydrazine moieties for their potential antifungal activities. This chemical series was identified with fair to excellent antifungal activities. Among this series, three molecules (Hyd.H, Hyd.OCH3, and Hyd.Cl) significantly reduced C. albicans viability, with rapid fungicidal activity. In addition, these three compounds exhibited significant antifungal activity against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. Hyd.H, Hyd.OCH3, and Hyd.Cl did not show any cytotoxicity against human cancer cell lines up to a concentration of 50 µg/mL and decreased Candida biofilm formation, with a significant reduction of 60% biofilm formation with Hyd.OCH3. In an infection model of Caenorhabditis elegans with C. albicans, hydrazine-based compounds significantly reduced nematode mortality. Overall, fungicidal activity was observed for Hyd.H, Hyd.OCH3, and Hyd.Cl against C. albicans, and these compounds protected C. elegans from C. albicans infection.

Quantitative proteomics revealed the transition of ergosterol biosynthesis and drug transporters processes during the development of fungal fluconazole resistance.

Fungal infections and antifungal resistance are the increasing global public health concerns. Mechanisms of fungal resistance include alterations in drug-target interactions, detoxification by high expression of drug efflux transporters, and permeability barriers associated with biofilms. However, the systematic panorama and dynamic changes of the relevant biological processes of fungal drug resistance acquisition remain limited. In this study, we developed a yeast model of resistance to prolonged fluconazole treatment and utilized the isobaric labels TMT (tandem mass tag)-based quantitative proteomics to analyze the proteome composition and changes in native, short-time fluconazole stimulated and drug-resistant strains. The proteome exhibited significant dynamic range at the beginning of treatment but returned to normal condition upon acquisition drug resistance. The sterol pathway responded strongly under a short time of fluconazole treatment, with increased transcript levels of most enzymes facilitating greater protein expression. With the drug resistance acquisition, the sterol pathway returned to normal state, while the expression of efflux pump proteins increased obviously on the transcription level. Finally, multiple efflux pump proteins showed high expression in drug-resistant strain. Thus, families of sterol pathway and efflux pump proteins, which are closely associated with drug resistance mechanisms, may play different roles at different nodes in the process of drug resistance acquisition. Our findings uncover the relatively important role of efflux pump proteins in the acquisition of fluconazole resistance and highlight its potential as the vital antifungal targets.

Genome-wide characterization and functional identification of MYB genes in Malus sieversii infected by Valsa mali.

Among the most important transcription factors in plants, the v-myb avian myeloblastosis viral oncogene homolog (MYB) regulates the expression network of response genes under stresses such as fungal infection. In China, the canker disease Valsa mali threatens the survival of Malus sieversii, an ancestor of cultivated apples. Using the M. sieversii genome, we identified 457 MsMYB and 128 R2R3-MsMYB genes that were randomly distributed across 17 chromosomes. Based on protein sequence and structure, the R2R3-MsMYB genes were phylogenetically divided into 29 categories, and 26 conserved motifs were identified. We further predicted cis-elements in the 2000-kb promoter region of R2R3-MsMYBs based on the genome. Transcriptome analysis of M. sieversii under V. mali infection showed that 27 R2R3-MsMYBs were significantly differentially expressed, indicating their key role in the response to V. mali infection. Using transient transformation, MsMYB14, MsMYB24, MsMYB39, MsMYB78, and MsMYB108, which were strongly induced by V. mali infection, were functionally identified. Among the five MsMYBs, MsMYB14 and MsMYB78 were both important in enhancing resistance to diseases, whereas MsMYB24 inhibited resistance. Based on the results of this study, we gained a better understanding of the MsMYB transcription factor family and laid the foundation for a future research program on disease prevention strategies in M. sieversii.

HSP90.2 modulates 2Q2-mediated wheat resistance against powdery mildew.

Wheat (Triticum aestivum L.) is a critical food crop feeding the world, but pathogens threaten its production. Wheat Heat Shock Protein 90.2 (HSP90.2) is a pathogen-inducible molecular chaperone folding nascent preproteins. Here, we used wheat HSP90.2 to isolate clients regulated at the posttranslational level. Tetraploid wheat hsp90.2 knockout mutant was susceptible to powdery mildew, while the HSP90.2 overexpression line was resistant, suggesting that HSP90.2 was essential for wheat resistance against powdery mildew. We next isolated 1500 clients of HSP90.2, which contained a wide variety of clients with different biological classifications. We utilized 2Q2, a nucleotide-binding leucine repeat-rich protein, as a model to investigate the potential of HSP90.2 interactome in fungal resistance. The transgenic line co-suppressing 2Q2 was more susceptible to powdery mildew, suggesting 2Q2 as a novel Pm-resistant gene. The 2Q2 protein resided in chloroplasts, and HSP90.2 played a critical role in the accumulation of 2Q2 in thylakoids. Our data provided over 1500 HSP90.2 clients with a potential regulation at the protein folding process and contributed a nontypical approach to isolate pathogenesis-related proteins.

Anti-Candida auris activity in vitro and in vivo of micafungin loaded nanoemulsions.

Fungi are becoming increasingly resistant, especially the new strains. Therefore, this work developed nanoemulsions (NE) containing micafungin (MICA), in order to improve its action against infections caused by Candida auris. The NEs were composed of the surfactants polyoxyethylene (20) cetyl ether (Brij 58®)/soy phosphatidylcholine at 10%, sunflower oil/cholesterol at 10%, and 80% PBS. The NEs were characterized by Dynamic Light Scattering (DLS). For the microbiological in vitro evaluation the determination of the minimum inhibitory concentration (MIC), ergosterol/sorbitol, time kill and biofilms tests were performed. Additionally, the antifungal activity was also evaluated in a Galleria mellonella model. The same model was used in order to evaluate acute toxicity. The NE showed a size of ∼ 42.12 nm, a polydispersion index (PDI) of 0.289, and a zeta potential (ZP) of -3.86 mV. NEM had an average size of 41.29 nm, a PDI of 0.259, and a ZP of -4.71 mV. Finally, both nanoemulsions showed good stability in a storage period of 3 months. Although NEM did not show activity in planktonic cells, it exhibited action against biofilm and in the in vivo infection model. In the alternative in vivo model assay, it was possible to observe that both, NEM and free MICA at 0.2 mg/l, was effective against the infection, being that NEM presented a better action. Finally, NEM and free MICA showed no acute toxicity up to 4 mg/l. NEM showed the best activities in in vitro in mature antibiofilm and in alternative in vivo models in G. mellonella. Although, NEs showed to be attractive for MICA transport in the treatment of infections caused by C. auris in vitro and in vivo studies with G. mellonella, further studies should be carried out, in mice, for example.

Candida auris is a fungus that can cause infections in the human body. As it is a microorganism with a high potential for resistance, it is extremely important to develop new therapeutic alternatives. Thus, nanotechnology, the science that studies materials with extremely small sizes, can be considered a promising method in the treatment of these infections.

Modified screening method of middle american dry bean genotypes reveals new genomic regions on Pv10 associated with anthracnose resistance.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib., is one of the most devastating diseases in dry bean (Phaseolus vulgaris L.) with seed yield losses up to 100%. Most anthracnose resistance genes thus far identified behave in a dominant manner and were identified by seedling screening. The Middle American Diversity Panel (MDP; n=266) was screened with a modified greenhouse screening method to evaluate the response to anthracnose race 73. Thirty MDP genotypes exhibited resistance to the race of which 16 genotypes were not known to contain anthracnose resistance genes to race 73. GWAS with ~93,000 SNP markers identified four genomic regions, two each on Pv01 and Pv10, associated race 73 resistance. A likelihood-ratio-based R2 analysis indicated the peak four SNP markers are responsible for 26% of the observed phenotypic variation, where one SNP, S10_072250, explains 23% of the total variation. SNP S10_072250 is associated with a new region of anthracnose resistance and is in an intron of a ZPR1-like gene. Further greenhouse testing of the 16 resistant lines without previously known resistance to race 73 revealed various levels of resistance under various levels of disease pressure. Disease resistance was further characterized in the field using four representative genotypes. GTS-900 and Remington exhibited field resistance while Merlot and Maverick were susceptible. Field testing with two different fungicide regimes revealed the resistant genotypes had no significant disease differences. The results suggest resistance to anthracnose may differ at various growth stages and that breeders have been selecting for major genes at early seedling stages while ignoring the effect of alternative genes that may be active at later stages. The newly identified resistant lines may be related to Age Related Resistance (ARR) and could be exploited as parental sources of anthracnose resistance in addition to already known major genes. The physical localization of the multiple regions of resistance confirms the presence of two clusters of disease resistance genes on Pv01 and identifies two new regions of anthracnose resistance on Pv10 possibly associated with ARR. Future research should look at the mode of inheritance of this resistance and its effect when combined with other anthracnose resistance loci.

A Complex Case of Aspergillus Infection of the Brain and Its Future Medical Implications.

Aspergillus is a fungal genus found worldwide, which causes infection most commonly in the respiratory system and in other systems, including the central nervous system. Fungal species, such as Aspergillus fumigatus or flavus, are more common in immunocompromised patient populations, such as those taking immunosuppressants post-transplantation, those on long-term corticosteroids, or those with immunodeficiencies such as AIDS. In this paper, we describe a rare case of aspergillosis that occurred due to a history of taking corticosteroids to treat arthritis pain in a patient with type 2 diabetes. Given the rise in antifungal-resistant species and environmental changes, it is noteworthy for further research to be conducted on new treatment plans and the management of such fungal infections to prepare against opportunistic infections caused by Aspergillus in the future.

Violacein and its antifungal activity: comments and potentialities.

Violacein is an important natural antimicrobial pigment that is mainly produced by Chromobacterium violaceum and Janthinobacterium lividum. It presents a significant range of effects against phytopathogenic and human fungi, besides being featured as having low toxicity, and by its important ecological role in protecting amphibian species and applications in dyed medical fabric. The hypothesis about violacein's action mechanisms against mucormycosis (Rhizopus arrhizus) and candidiasis (Candida auris) is herein discussed based on data available in the scientific literature.

Photosensitizer-Polypeptide Conjugate for Effective Elimination of Candida albicans Biofilm.

Persistent fungal infections caused by biofilms seriously endanger human health. In this study, a photosensitizer-polypeptide conjugate (PPa-cP) comprising a photosensitizer, pyropheophorbide a (PPa), and a cationic polypeptide (cP) is readily synthesized for effective antifungal and antibiofilm treatment. Compared with free PPa, the cationic PPa-cP shows enhanced binding ability to the negatively charged surface of Candida albicans (C. albicans) through electrostatic interactions. As a result, PPa-cP exhibits effective antifungal efficiency against both C. albicans and fluconazole-resistant C. albicans in vitro under light irradiation. The minimum inhibitory concentration (MIC) of PPa-cP for both C. albicans and fluconazole-resistant C. albicans is 1 µm. In addition, PPa-cP also shows improved penetration in a C. albicans biofilm, thus effectively eliminating the C. albicans biofilm by photodynamic effects. More importantly, PPa-cP demonstrats significantly enhanced therapeutic effects in a fluconazole-resistant C. albicans-infected rat model with minimal side effects. In conclusion, the current work presents an effective strategy to combat biofilm infections associated with biomedical equipment.