Sixty years of Amphotericin B: An Overview of the Main Antifungal Agent Used to Treat Invasive Fungal Infections

Lansoprazole interferes with fungal respiration and acts synergistically with amphotericin B against multidrug-resistant Candida auris

Candida auris has emerged as a problematic fungal pathogen associated with high morbidity and mortality. Amphotericin B (AmB) is the most effective antifungal used to treat invasive fungal candidiasis, with resistance rarely observed among clinical isolates. However, C. auris possesses extraordinary resistant profiles against all available antifungal drugs, including AmB. In our pursuit of potential solutions, we screened a panel of 727 FDA-approved drugs. We identified the proton pump inhibitor lansoprazole (LNP) as a potent enhancer of AmB's activity against C. auris. LNP also potentiates the antifungal activity of AmB against other medically important species of Candida and Cryptococcus. Our investigations into the mechanism of action unveiled that LNP metabolite(s) interact with a crucial target in the mitochondrial respiratory chain (complex III, known as cytochrome bc1). This interaction increases oxidative stress within fungal cells. Our results demonstrated the critical role of an active respiratory function in the antifungal activity of LNP. Most importantly, LNP restored the efficacy of AmB in an immunocompromised mouse model, resulting in a 1.7-log (∼98%) CFU reduction in the burden of C. auris in the kidneys. Our findings strongly advocate for a comprehensive evaluation of LNP as a cytochrome bc1 inhibitor for combating drug-resistant C. auris infections.

Histoplasmosis around the world: A global perspective on the presentation, virulence factors, and treatment of histoplasmosis

Histoplasmosis is a systemic infection caused by an endemic dimorphic fungus, Histoplasma capsulatum. Though prevalent in the eastern United States of America, near the Ohio and Mississippi River Valleys, the evidence underlying the global prevalence of histoplasmosis, especially in immunocompromised populations, is underappreciated. This article highlights the global epidemiology, risk factors, microbiology and pathophysiological characteristics, pulmonary and extrapulmonary manifestations, prevention measures, radiographic patterns, diagnostic techniques, and antifungal treatment approaches for Histoplasma capsulatum.

Cervical Intradural Fungal Infection Masquerading as a Meningioma in an Immunocompetent Patient: A Case Report and Systematic Review

BACKGROUND

Intradural spinal fungal infection is a rare phenomenon that can carry a significant increase in morbidity and mortality. This systematic review and case report provides a presentation of a 75-year-old male patient with an intradural cervical mass that was diagnosed as a fungal infection intraoperatively. We analyze and report on intradural spinal fungal infections in immunocompetent patients.

METHODS

We performed a systematic literature review following the PRISMA protocol for studies of intradural fungal infections published in the past 25 years. Original articles with a description of treatment outcomes of such patients were included.

RESULTS

A total of 8 studies were included in this review with the addition of the present case. There were 5 male and 4 female patients with an average age of 45.6 yeaers (range 24-75 years). Aspergillus and Candida species being the most isolated fungal organism. The origin of the lesions was identified and iatrogenic in 4 cases. Most patients underwent decompressive laminectomy with biopsy, abscess drainage, or resection of the identified lesion. There were 2 instances of cervical lesions, but most of the lesions were in the thoracic and lumbar spine. Half of the cases reported symptoms improvement, but 2 patients died from the infection or complications from the infections.

CONCLUSIONS

Intradural fungal infections are rare, with only 10 total cases reported in the past 25 years. Nonetheless, they can be associated with significant mortality and morbidity. Thus, the timeline from presentation to intervention should be evaluated and determined carefully.

Amphotericin B for injection triggers degranulation of human LAD2 mast cells by MRGPRX2 and pseudo-allergic reactions in mice via MRGPRB2 activation

Amphotericin B, a polyene macrolide antifungal agent, still plays an important role in the management of serious systemic fungal infections. Amphotericin B deoxycholate (AmBd) has been used to treat invasive fungal infections for over 60 years and remains the primary clinical formulation currently available. Anaphylactoid reactions triggered by AmBd in the clinic have been documented. However, the molecular and cellular events contributing to these reactions have not been clearly elucidated to date. This study demonstrates that the human Mas-related G protein-coupled receptor X2 (MRGPRX2) is the receptor that mediates these anaphylactoid responses. Molecular docking and cellular thermal shift assay (CETSA) indicate that AmBd exhibits potential affinity with MRGPRX2. In vitro, exposure to AmBd results in significant release of LAD2 mast cell granules and induces intracellular Ca2+ mobilization as well as activation of PLC-γ/IP3R and PI3K/AKT signaling pathways. However, these phenomena are reduced in MRGPRX2-knockdown LAD2 cells. In vivo, AmBd triggers paw swelling and a rapid drop in core body temperature in wild-type (WT) mice. However, these reactions are almost absent in MRGPRB2 (the mouse homolog of MRGPRX2) knockout mice (MRGPRB2MUT, MUT). The above results suggest that AmBd activates PLC-γ/IP3R and PI3K/AKT signaling via MRGPRX2 (in human LAD2 mast cells) or MRGPRB2 (in mice), leading to the release of mast cell granules and subsequent triggering of pseudo-allergic reactions. Taken together, this study clarifies the role of MRGPRX2 in triggering pseudo-allergic reactions to AmBd and suggests that MRGPRX2 could be a potential therapeutic target for controlling these reactions.

How can we optimize antifungal use and stewardship in the treatment of acute leukemia?

INTRODUCTION

The global need for antifungal stewardship is driven by spreading antimicrobial and antifungal resistance. Triazoles are the only oral and relatively well-tolerated class of antifungal medications, and usage is associated with acquired resistance and species replacement with intrinsically resistant organisms. On a per-patient basis, hematology patients are the largest inpatient consumers of antifungal drugs, but are also the most vulnerable to invasive fungal disease.

AREAS COVERED

In this review we discuss available and forthcoming antifungal drugs, antifungal prophylaxis and empiric antifungal therapy, and how a screening based and diagnostic-driven approach may be used to reduce antifungal consumption. Finally, we discuss components of an antifungal stewardship program, interventions that can be employed, and how impact can be measured. The search methodology consisted of searching PubMed for journal articles using the term antifungal stewardship plus program, intervention, performance measure or outcome before 1 January 2024.

EXPERT OPINION

Initial focus should be on implementing effective antifungal stewardship programs by developing and implementing local guidelines and using interventions, such as post-prescription review and feedback, which are known to be effective. Technologies such as microbiome analysis and machine learning may allow the development of truly individualized risk-factor-based approaches to antifungal stewardship in the future.

Inhibition of Development and Metabolism of Dual-Species Biofilms of Candida albicans and Candida krusei (Pichia kudriavzevii) by Organoselenium Compounds

Although Candida albicans is the most frequently identified Candida species in clinical settings, a significant number of infections related to the non-albicans Candida (NAC) species, Candida krusei, has been reported. Both species are able to produce biofilms and have been an important resistance-related factor to antimicrobial resistance. In addition, the microbial relationship is common in the human body, contributing to the formation of polymicrobial biofilms. Considering the great number of reports showing the increase in cases of resistance to the available antifungal drugs, the development of new and effective antifungal agents is critical. The inhibitory effect of Organoselenium Compounds (OCs) on the development of Candida albicans and Candida krusei was recently demonstrated, supporting the potential of these compounds as efficient antifungal drugs. In addition, OCs were able to reduce the viability and the development of biofilms, a very important step in colonization and infection caused by fungi. Thus, the objective of this study was to investigate the effect of the Organoselenium Compounds (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2 on the development of dual-species biofilms of Candida albicans and Candida krusei produced using either RPMI-1640 or Sabouraud Dextrose Broth (SDB) media. The development of dual-species biofilms was evaluated by the determination of both metabolic activity, using a metabolic assay based on the reduction of XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide sodium salt) assay and identification of either Candida albicans and Candida krusei on CHROMagar Candida medium. Biofilm formation using RPMI-1640 was inhibited in 90, 55, and 20% by 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively. However, biofilms produced using SDB presented an inhibition of 62, 30 and 15% in the presence of 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively. The metabolic activity of 24 h biofilms was inhibited by 35, 30 and 20% by 30 µM (p-MeOPhSe)2, (PhSe)2, and (p-Cl-PhSe)2, respectively, with RPMI-1640; however, 24 h biofilms formed using SDB were not modified by the OCs. In addition, a great reduction in the number of CFUs of Candida albicans (93%) in biofilms produced using RPMI-1640 in the presence of 30 µM (p-MeOPhSe)2 was observed. However, biofilms formed using SDB and treated with 30 µM (p-MeOPhSe)2 presented a reduction of 97 and 69% in the number of CFUs of Candida albicans and Candida krusei, respectively. These results demonstrated that Organoselenium Compounds, mainly (p-MeOPhSe)2, are able to decrease the metabolic activity of dual-species biofilms by reducing both Candida albicans and Candida krusei cell number during biofilm formation using either RPMI-1640 or SDB. Taken together, these results demonstrated the potential of the OCs to inhibit the development of dual-species biofilms of Candida albicans and Candida krusei.

Amidine containing compounds: Antimicrobial activity and its potential in combating antimicrobial resistance

Antimicrobial resistance (AMR) is a growing and concerning threat to global public health, necessitating innovative strategies to combat this crisis. Amidine-containing compounds have emerged as promising agents in the battle against AMR. This review gives a summary of recent advances from the past decade in studies of antimicrobial amidine-containing compounds with the aim to feature their structural diversity and the pharmacological relevance of the moiety to antimicrobial activity and their potential use in combating antimicrobial resistance, to the greatest extent possible. Highlighting is put on chemical structure of such compounds in relation to antimicrobial activities such as antibacterial, antifungal, and antiparasitic activities. Researchers commonly modify molecules containing amidine or incorporate amidine into existing antimicrobial agents to enhance their pharmacological attributes and combat antimicrobial resistance. This comprehensive review consolidates the current knowledge on amidine-containing compounds, elucidating their antimicrobial mechanisms and highlighting their promise in addressing the global AMR crisis. By offering a multidisciplinary perspective, we aim to inspire further research and innovation in this critical area of antimicrobial research.

Potential Use of Common Administration of Emulsion for Parenteral Nutrition and Vinpocetine: Compatibility Study and Prospect

Vinpocetine (VP) is distributed after oral and intravenous administration, and its uptake in the thalamus, basal ganglia, and visual cortex. Due to poor bioavailability (~7%) and marked first-pass effect (~75%), including a short half-life (2-3 h), oral administration of VP is limited. It requires frequent administration of the drug to obtain a therapeutic effect. Attempts to overcome these difficulties include the use of new drug delivery systems and/or alternative routes of drug administration. One possibility is the common administration of lipid emulsion and drug using the same catheter. However, this procedure is not recommended due to potential interaction and lack of safety data. For this purpose, we checked the compatibility of VP solutions with eight commercially available parenteral nutrition admixtures, i.e., Lipoflex special, Omegaflex special, Lipoflex peri, Omegaflex peri, Kabiven, SmofKabiven, Kabiven Peripheral, and Olimel Peri N4E. Coadministration is only possible if the stability of the drug and the lipid emulsion is confirmed. The available data are scarce and only concern the incompatibility of VP with ibuprofen. Compatibility tests were carried out in simulated administration through a Y-site connector using clinical flow rates. The stability of the drug and lipid emulsion was assessed by visual inspection and measurement of pH, osmolality, particle size as mean droplet diameter (MDD) and percentage of lipids residing in globules larger than 5 µm (PFAT5), zeta potential, polydispersity index, and lipid-free parenteral nutrition admixture(PNA) turbidity. The results of the compatibility of VP with eight commercial PN admixtures showed that all lipid emulsions show different signs of destabilization. In the studied samples, particles larger than 1000 nm, a significant increase in MDD, zeta potential, and loss of homogeneity visible as an increase in the polydispersity index were observed. Most of the samples had PFAT5 above the USP limit (0.05%). Taking into account the obtained data, VP should not be administered with the studied lipid emulsions for parenteral nutrition.

Plausible mechanism of drug resistance and side-effects of COVID-19 therapeutics: a bottleneck for its eradication

BACKGROUND

COVID-19 pandemic has turned our world upside down by meddling with our normal lives. While there is no definitive drug against SARS-CoV-2, antiviral drugs that are already in the market, are being repurposed against it, could now complete long-term as well as all age-specific investigations, and they are successful in saving millions of lives. Nevertheless, side-effects are emergingly seen in the patients undergoing treatment, and ineffectiveness is increasingly found due to the emerging notorious variants of the virus. Many of them are also facing serious co-infections including black fungus, Zika, and H1N1 virus to name a few.

OBJECTIVES

Therefore, this review highlights both drug resistance, their side-effects, and the significance for proper and long-term clinical trials of all age groups including children.

METHODS

We have explored and proposed the mechanisms of drug resistance that may arise due to the misuse or overuse of drugs based on available experimental reports.

RESULTS

The review provides solutions to the aforesaid issues of drug-resistance and side-effects by providing combination therapies, ancillary treatments, and other preventive strategies that can be useful in preventing drawbacks thereby curbing COVID-19 or similar future infections to maintain our normal lives.

CONCLUSION

COVID-19 and its long-term effects, if any, can be eradicated with strategic and mindful use of related therapeutics in a controlled manner.

Sterol 14-alpha demethylase (CYP51) activity in Leishmania donovani is likely dependent upon cytochrome P450 reductase 1

Liposomal amphotericin B is an important frontline drug for the treatment of visceral leishmaniasis, a neglected disease of poverty. The mechanism of action of amphotericin B (AmB) is thought to involve interaction with ergosterol and other ergostane sterols, resulting in disruption of the integrity and key functions of the plasma membrane. Emergence of clinically refractory isolates of Leishmania donovani and L. infantum is an ongoing issue and knowledge of potential resistance mechanisms can help to alleviate this problem. Here we report the characterisation of four independently selected L. donovani clones that are resistant to AmB. Whole genome sequencing revealed that in three of the moderately resistant clones, resistance was due solely to the deletion of a gene encoding C24-sterol methyltransferase (SMT1). The fourth, hyper-resistant resistant clone (>60-fold) was found to have a 24 bp deletion in both alleles of a gene encoding a putative cytochrome P450 reductase (P450R1). Metabolic profiling indicated these parasites were virtually devoid of ergosterol (0.2% versus 18% of total sterols in wild-type) and had a marked accumulation of 14-methylfecosterol (75% versus 0.1% of total sterols in wild-type) and other 14-alpha methylcholestanes. These are substrates for sterol 14-alpha demethylase (CYP51) suggesting that this enzyme may be a bona fide P450R specifically involved in electron transfer from NADPH to CYP51 during catalysis. Deletion of P450R1 in wild-type cells phenocopied the metabolic changes observed in our AmB hyper-resistant clone as well as in CYP51 nulls. Likewise, addition of a wild type P450R1 gene restored sterol profiles to wild type. Our studies indicate that P450R1 is essential for L. donovani amastigote viability, thus loss of this gene is unlikely to be a driver of clinical resistance. Nevertheless, investigating the mechanisms underpinning AmB resistance in these cells provided insights that refine our understanding of the L. donovani sterol biosynthetic pathway.

Overexpression of PDR16 Confers Amphotericin B Resistance in a PMP3-Dependent Manner in Yeast Saccharomyces cerevisiae

Invasive fungal infections in humans with compromised immune systems are the primary cause of morbidity and mortality, which is becoming more widely acknowledged. Amphotericin B (AmB) is one of the antifungal drugs used to treat such infections. AmB binds with plasma membrane ergosterol, inducing cellular ions to leak and causing cell death. Reduction in ergosterol content and modification of cell walls have been described as AmB resistance mechanisms. In addition, when the sphingolipid level is decreased, the cell becomes more susceptible to AmB. Previously, PDR16, a gene that encodes phosphatidylinositol transfer protein in Saccharomyces cerevisiae, was shown to enhance AmB resistance upon overexpression. However, the mechanism of PDR16-mediated AmB resistance is not clear. Here, in this study, it was discovered that a plasma membrane proteolipid 3 protein encoded by PMP3 is essential for PDR16-mediated AmB resistance. PDR16-mediated AmB resistance does not depend on ergosterol, but a functional sphingolipid biosynthetic pathway is required. Additionally, PMP3-mediated alteration in membrane integrity abolishes PDR16 mediated AmB resistance, confirming the importance of PMP3 in the PDR16 mediated AmB resistance.

A Study on the Effect of Quaternization of Polyene Antibiotics' Structures on Their Activity, Toxicity, and Impact on Membrane Models

Polyene antibiotics have been used in antifungal therapy since the mid-twentieth century. They are highly valued for their broad spectrum of activity and the rarity of pathogen resistance to their action. However, their use in the treatment of systemic mycoses often results in serious side-effects. Recently, there has been a renewed interest in the development of new antifungal drugs based on polyenes, particularly due to the emergence of highly dangerous pathogenic strains of fungi, such as Candida auris, and the increased incidence of mucormycosis. Considerable understanding has been established regarding the structure-biological activity relationships of polyene antifungals. Yet, no previous studies have examined the effect of introducing quaternized fragments into their molecular structure. In this study, we present a series of amides of amphotericin B, nystatin, and natamycin bearing a quaternized group in the side chain, and discuss their biological properties: antifungal activity, cytotoxicity, and effects on lipid bilayers that mimic fungal and mammalian cell membranes. Our research findings suggest that the nature of the introduced quaternized residue plays a more significant role than merely the introduction of a constant positive charge. Among the tested polyenes, derivatives 4b, 5b, and 6b, which contain a fragment of N-methyl-4-(aminomethyl)pyridinium in their structure, are particularly noteworthy due to their biological activity.

Discovering type I cis-AT polyketides through computational mass spectrometry and genome mining with Seq2PKS

Type 1 polyketides are a major class of natural products used as antiviral, antibiotic, antifungal, antiparasitic, immunosuppressive, and antitumor drugs. Analysis of public microbial genomes leads to the discovery of over sixty thousand type 1 polyketide gene clusters. However, the molecular products of only about a hundred of these clusters are characterized, leaving most metabolites unknown. Characterizing polyketides relies on bioactivity-guided purification, which is expensive and time-consuming. To address this, we present Seq2PKS, a machine learning algorithm that predicts chemical structures derived from Type 1 polyketide synthases. Seq2PKS predicts numerous putative structures for each gene cluster to enhance accuracy. The correct structure is identified using a variable mass spectral database search. Benchmarks show that Seq2PKS outperforms existing methods. Applying Seq2PKS to Actinobacteria datasets, we discover biosynthetic gene clusters for monazomycin, oasomycin A, and 2-aminobenzamide-actiphenol.

Case report: Dermatophytic pseudomycetoma in a domestic Korean short hair cat treated with intralesional injection of amphotericin B and oral terbinafine administration

Dermatophytic pseudomycetoma (DPM), which is a deeper dermal and/or subcutaneous infection of dermatophytes, has been rarely reported in Domestic Korean Short Hair Cats. A 3-year-old, spayed female, domestic Korean Short Hair Cat presented with a history of crusts, nodules, and pruritus for 1 year. At the initial presentation, multifocal ulcerative nodules covered with yellowish grains were noted on her ventral thorax, abdomen, flank, and left hindlimb. Cytology of ulcerative nodules revealed degenerative neutrophils, macrophages, multinucleated giant cells, and hyphae. Histological examination of nodules revealed pyogranulomatous dermatitis with fungal plaques, and Microsporum canis and Staphylococcus aureus were identified in the culture. Therefore, the cat was diagnosed with DPM with secondary pyoderma. Oral itraconazole (10 mg/kg, once a day) was administered, but no significant improvement was observed. Therefore, intralesional (IL) injection of amphotericin B (0.6 mg/nodule) and oral administration of terbinafine (30 mg/kg, twice a day) were administered to the cat. With these medications, ulceration and the number and size of nodules decreased significantly, although large dome-shaped nodules remained. Skin lesions were treated with oral terbinafine and itraconazole administration for 5 months. However, after 6 months, recurrence of multifocal ulcerative nodules was observed, and the cat died 10 months after initial presentation. In this case, IL amphotericin B and oral terbinafine administration were partially effective in DPM treatment, suggesting that this may be an option for DPM treatment. Further studies to determine dose and frequency of IL amphotericin B in the management of DPM are warranted.

Compare the efficacy of antifungal agents as primary therapy for invasive aspergillosis: a network meta-analysis

BACKGROUND

Several antifungal agents are available for primary therapy in patients with invasive aspergillosis (IA). Although a few studies have compared the effectiveness of different antifungal agents in treating IA, there has yet to be a definitive agreement on the best choice. Herein, we perform a network meta-analysis comparing the efficacy of different antifungal agents in IA.

METHODS

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Clinical Trials databases to find studies (both randomized controlled trials [RCTs] and observational) that reported on treatment outcomes with antifungal agents for patients with IA. The study quality was assessed using the revised tool for risk of bias and the Newcastle Ottawa scale, respectively. We performed a network meta-analysis (NMA) to summarize the evidence on antifungal agents' efficacy (favourable response and mortality).

RESULTS

We found 12 studies (2428 patients) investigating 11 antifungal agents in the primary therapy of IA. There were 5 RCTs and 7 observational studies. When treated with monotherapy, isavuconazole was associated with the best probability of favourable response (SUCRA, 77.9%; mean rank, 3.2) and the best reduction mortality against IA (SUCRA, 69.1%; mean rank, 4.1), followed by voriconazole and posaconazole. When treated with combination therapy, Liposomal amphotericin B plus caspofungin was the therapy associated with the best probability of favourable response (SUCRA, 84.1%; mean rank, 2.6) and the best reduction mortality (SUCRA, 88.2%; mean rank, 2.2) against IA.

CONCLUSION

These findings suggest that isavuconazole, voriconazole, and posaconazole may be the best antifungal agents as the primary therapy for IA. Liposomal amphotericin B plus caspofungin could be an alternative option.

Redox homeostasis in human renal cells that had been treated with amphotericin B in combination with selected 1,3,4-thiadiazole derivatives

BACKGROUND

The use of amphotericin B (AmB) in the therapy of systemic mycosis is associated with strong side effects, including nephrotoxicity, and hepatotoxicity. Therefore, agents that can reduce the toxic effects of AmB while acting synergistically as antifungal agents are currently being sought. 1,3,4-thiadiazole derivatives are promising compounds that have an antifungal activity and act synergically with AmB. Such combinations might allow the dose of AmB, which is essential for preventing patients from having serious side effects, to be decreased. This might result from the antioxidant properties of 1,3,4-thiadiazoles. Thus, the aim of the study was to investigate redox homeostasis in human renal proximal tubule epithelial cells (RPTEC) after they had been treated with AmB in combination with 1,3,4-thiadiazole derivatives.

METHODS

Cellular redox homeostasis was assessed by investigating the total antioxidant capacity (TAC) of cells, the malondialdehyde (MDA) concentration, and the activity of antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT). TAC was measured using an ABTS method. The MDA concentration, and the activity of SOD, GPX, and CAT were determined spectrophotometrically using commercially available assays. Additionally, the antioxidant defense system-related gene expression profile was determined using oligonucleotide microarrays (HG-U133A 2.0). Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to confirm the microarray results.

RESULTS

Amphotericin B and selected 1,3,4-thiadiazole derivatives had a significant effect on the total antioxidant capacity of the RPTEC cells, and the activity of the antioxidant enzymes. We also revealed that the effect of thiadiazoles on the SOD and CAT activities is dependent on the treatment of RPTEC cells with AmB. At the transcriptional level, the expression of several genes was affected by the studied compounds and their combinations.

CONCLUSIONS

The results confirmed that thiadiazoles can stimulate the RPTEC cells to defend against the oxidative stress that is generated by AmB. In addition, together with the previously demonstrated synergistic antifungal activity, and low nephrotoxicity, these compounds have the potential to be used in new therapeutic strategies in the treatment of fungal infections.

"Click" amphotericin B in prodrug nanoformulations for enhanced systemic fungemia treatment

Severe nephrotoxicity and infusion-related side effects pose significant obstacles to the clinical application of Amphotericin B (AmB) in life-threatening systemic fungal infections. In pursuit of a cost-effective and safe formulation, we have introduced multiple phenylboronic acid (PBA) moieties onto a linear dendritic telodendrimer (TD) scaffold, enabling effective AmB conjugation via boronate chemistry through a rapid, high yield, catalysis-free and dialysis-free "Click" drug loading process. Optimized AmB-TD prodrugs self-assemble into monodispersed micelles characterized by small particle sizes and neutral surface charges. AmB prodrugs sustain drug release in circulation, which is accelerated in response to the acidic pH and Reactive Oxygen Species (ROS) in the infection and inflammation. Prodrugs mitigate the AmB aggregation status, reduce cytotoxicity and hemolytic activity compared to Fungizone®, and demonstrate superior antifungal activity to AmBisome®. AmB-PEG5kBA4 has a comparable maximum tolerated dose (MTD) to AmBisome®, while over 20-fold increase than Fungizone®. A single dose of AmB-PEG5kBA4 demonstrates superior efficacy to Fungizone® and AmBisome® in treating systemic fungal infections in both immunocompetent and immunocompromised mice.

Amphotericin B loaded nanoemulsion: Optimization, characterization and in-vitro activity against L. donovani promastigotes

The present work aimed to develop and evaluate AmB-loaded nano-emulsion (AmB-NE) which will augment the solubility of AmB and lead to enhanced anti-leishmanial activity. The composition of AmB-NE was optimized by systematic screening followed by DoE-extreme vertices mixture design. The optimized NE revealed mean droplet size and PDI of 44.19 ± 5.5 nm, 0.265 ± 0.0723, respectively. The NE could efficiently encapsulate AmB with drug content and efficiency 83.509 ± 0.369% and 81.659 ± 0.013%, respectively. The presence of cholesterol and stearyl amine retarded the release (P < 0.0001) of AmB significantly compared to AmB suspension. The AmB-NE and pure AmB suspension demonstrated the IC50 of 0.06309 μg/mL and 0.3309 μg/mL against L.donovani promastigotes after 48 h incubation. The formulation was robust at all exaggerated stability conditions such as freeze-thaw and centrifugation. These findings indicate that AmB-NE is an attractive approach to treat visceral leishmaniasis with improved activity.

The interaction of plant flavones with amphotericin B: Consequences for its pore-forming ability

The growth of antibiotic resistance to antifungal drugs contributes to the search for new ways to enhance their effectiveness and reduce toxicity. The undeniable advantage of polyene macrolide antibiotic amphotericin B (AmB) which ensures low pathogen resistance is its mechanism of action related to the formation of transmembrane pores in target lipid membranes. Here, we investigated the effects of plant flavones, chrysin, wogonin, baicalein, apigenin, scutellarein, luteolin, morin and fisetin on the pore-forming activity of AmB in the sterol-enriched membranes by electrophysiological assays. Сhrysin, wogonin, baicalein, apigenin, scutellarein, and luteolin were shown to decrease the AmB pore-forming activity in the bilayers composed of palmitoyloleylphosphocholine independently of their sterol composition. Morin and fisetin led to the increase and decrease in the AmB pore-forming activity in the ergosterol- and cholesterol-containing bilayers respectively. Differential scanning microcalorimetry of the gel-to-liquid crystalline phase transition of membrane forming lipids, molecular dynamics simulations, and absorbance spectroscopy revealed the possibility of direct interactions between AmB and some flavones in the water and/or in the lipid bilayer. The influence of these interactions on the antibiotic partitioning between aqueous solution and membrane and/or its transition between different states in the bilayer was discussed.

Advancements in nanoparticle-based therapies for multidrug-resistant candidiasis infections: a comprehensive review

Candida auris, a rapidly emerging multidrug-resistant fungal pathogen, poses a global health threat, with cases reported in over 47 countries. Conventional detection methods struggle, and the increasing resistance ofC. auristo antifungal agents has limited treatment options. Nanoparticle-based therapies, utilizing materials like silver, carbon, zinc oxide, titanium dioxide, polymer, and gold, show promise in effectively treating cutaneous candidiasis. This review explores recent advancements in nanoparticle-based therapies, emphasizing their potential to revolutionize antifungal therapy, particularly in combatingC. aurisinfections. The discussion delves into mechanisms of action, combinations of nanomaterials, and their application against multidrug-resistant fungal pathogens, offering exciting prospects for improved clinical outcomes and reduced mortality rates. The aim is to inspire further research, ushering in a new era in the fight against multidrug-resistant fungal infections, paving the way for more effective and targeted therapeutic interventions.

Synergistic activity of gold nanoparticles with amphotericin B on persister cells of Candida tropicalis biofilms

AIM

The antifungal activity was studied on sessile and persister cells (PCs) of Candida tropicalis biofilms of gold nanoparticles (AuNPs) stabilized with cetyltrimethylammonium bromide (CTAB-AuNPs) and those conjugated with cysteine, in combination with Amphotericin B (AmB).

MATERIALS/METHODS

The PC model was used and synergistic activity was tested by the checkerboard assay. Biofilms were studied by crystal violet and scanning electron microscopy.

RESULTS/CONCLUSIONS

After the combination of both AuNPs and AmB the biofilm biomass was reduced, with significant differences in architecture being observed with a reduced biofilm matrix. In addition, the CTAB-AuNPs-AmB combination significantly reduced PCs. Understanding how these AuNPs aid in the fight against biofilms and the development of new approaches to eradicate PCs has relevance for chronic infection treatment.

Late-stage diversification of bacterial natural products through biocatalysis

Bacterial natural products (BNPs) are very important sources of leads for drug development and chemical novelty. The possibility to perform late-stage diversification of BNPs using biocatalysis is an attractive alternative route other than total chemical synthesis or metal complexation reactions. Although biocatalysis is gaining popularity as a green chemistry methodology, a vast majority of orphan sequenced genomic data related to metabolic pathways for BNP biosynthesis and its tailoring enzymes are underexplored. In this review, we report a systematic overview of biotransformations of 21 molecules, which include derivatization by halogenation, esterification, reduction, oxidation, alkylation and nitration reactions, as well as degradation products as their sub-derivatives. These BNPs were grouped based on their biological activities into antibacterial (5), antifungal (5), anticancer (5), immunosuppressive (2) and quorum sensing modulating (4) compounds. This study summarized 73 derivatives and 16 degradation sub-derivatives originating from 12 BNPs. The highest number of biocatalytic reactions was observed for drugs that are already in clinical use: 28 reactions for the antibacterial drug vancomycin, followed by 18 reactions reported for the immunosuppressive drug rapamycin. The most common biocatalysts include oxidoreductases, transferases, lipases, isomerases and haloperoxidases. This review highlights biocatalytic routes for the late-stage diversification reactions of BNPs, which potentially help to recognize the structural optimizations of bioactive scaffolds for the generation of new biomolecules, eventually leading to drug development.

How Does the Antibiotic Amphotericin B Enter Membranes and What Does It Do There?

Amphotericin B is a popular antifungal antibiotic, but the exact way it works is still a matter of debate. Here, we used monolayers composed of phosphatidylcholine with ergosterol as a model of fungal lipid membranes to study drug incorporation from the aqueous phase and analyze the molecular reorganization of membranes underlying the biological activity of the antibiotic. The results show that the internalization of antibiotic molecules into membranes occurs only in the presence of ergosterol in the lipid phase. Comparison of images of solid-supported monolayers obtained by atomic force microscopy and lifetime imaging fluorescence microscopy shows the formation of intramembrane clusters of various sizes in the lipid phase, consisting mainly of antibiotic dimers and relatively large membrane pores (∼15 nm in diameter). The results reveal multiple modes of action of amphotericin B, acting simultaneously, each of which adversely affects the structural properties of the lipid membranes and their physiological functionality.

Regulation of renal nitric oxide and eNOS/iNOS expression by tadalafil participates in the mitigation of amphotericin B-induced renal injury: Down-regulation of NF-κB/iNOS/caspase-3 signaling

Amphotericin B (AmB)-induced acute kidney injury (AKI) is a common health problem having an undesirable impact on its urgent therapeutic utility for fatal systemic fungal infections. Tadalafil (TAD), a phosphodiesterase-5 (PDE-5) inhibitor, has been observed to have a wide range of pharmacological actions, including nephroprotection. The study's objective was to examine the possible underlying protective mechanism of TAD against AmB-induced nephrotoxicity. Experimentally, animals were divided randomly into four groups: control, TAD (5 mg/kg/day; p.o.), AmB (18.5 mg/kg/day; i.p.), and TAD+AmB groups. Sera and tissue samples were processed for biochemical, molecular, and histological analyses. The biochemical investigations showed that TAD significantly ameliorated the increase of kidney function biomarkers (creatinine, urea, CysC, KIM-1) in serum, renal nitric oxide (NO), lipid peroxidation (MDA), and inflammatory cytokines (TNF-α, IL-6) in AmB-treated rats. Meanwhile, TAD significantly retarded AmB-induced decrease in serum magnesium, sodium, potassium, and renal glutathione content. Molecular analysis revealed that TAD reduced AmB-induced imbalance in the protein expression of eNOS/iNOS, which explains its regulatory effect on renal NO content. These results were also supported by the down-regulation of nuclear NF-κB p65 and cleaved caspase-3 protein expressions, as well as the improvement of histological features by TAD in AmB-treated rats. Therefore, it can be suggested that TAD could be a promising candidate for renoprotection against AmB-induced AKI. That could be partly attributed to its regulatory effect on renal eNOS/iNOS balance and NO, the inhibition of NF-κB p65 nuclear translocation, its downstream inflammatory cytokines and iNOS, and ultimately the inhibition of caspase-3-induced renal apoptosis.

Antifungal drug resistance in Candida: a special emphasis on amphotericin B

Invasive fungal infections in humans caused by several Candida species, increased considerably in immunocompromised or critically ill patients, resulting in substantial morbidity and mortality. Candida albicans is the most prevalent species, although the frequency of these organisms varies greatly according to geographic region. Infections with C. albicans and non-albicans Candida species have become more common, especially in the past 20 years, as a result of aging, immunosuppressive medication use, endocrine disorders, malnourishment, extended use of medical equipment, and an increase in immunogenic diseases. Despite C. albicans being the species most frequently associated with human infections, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei also have been identified. Several antifungal drugs with different modes of action are approved for use in clinical settings to treat fungal infections. However, due to the common eukaryotic structure of humans and fungi, only a limited number of antifungal drugs are available for therapeutic use. Furthermore, drug resistance in Candida species has emerged as a result of the growing use of currently available antifungal drugs against fungal infections. Amphotericin B (AmB), a polyene class of antifungal drugs, is mainly used for the treatment of serious systemic fungal infections. AmB interacts with fungal plasma membrane ergosterol, triggering cellular ion leakage via pore formation, or extracting the ergosterol from the plasma membrane inducing cellular death. AmB resistance is primarily caused by changes in the content or structure of ergosterol. This review summarizes the antifungal drug resistance exhibited by Candida species, with a special focus on AmB.

What do We Know about Cryptic Aspergillosis?

Cryptic Aspergillus species are increasingly recognized as pathogens involved in human disease. They are ubiquitarian fungi with high tenacity in their environment and can express various resistance mechanisms, often due to exposure to antifungal agents employed in agriculture and farming. The identification of such species is increasing thanks to molecular techniques, and a better description of this type of pathogen is granted. Nevertheless, the number of species and their importance in the clinical setting still need to be well studied. Furthermore, their cross-sectional involvement in animal disease, plants, and human activities requires a multidisciplinary approach involving experts from various fields. This comprehensive review aims to provide a sharp vision of the cryptic Aspergillus species, from the importance of correct identification to the better management of the infections caused by these pathogens. The review also accentuates the importance of the One Health approach for this kind of microorganism, given the interconnection between environmental exposure and aspergillosis, embracing transversely the multidisciplinary process for managing the cryptic Aspergillus species. The paper advocates the need for improving knowledge in this little-known species, given the burden of economic and health implications related to the diffusion of these bugs.

Synergistic action of synthetic peptides and amphotericin B causes disruption of the plasma membrane and cell wall in Candida albicans

The objective of this work was to evaluate the combination of synthetic peptides based on the γ-core motif of defensin PvD1 with amphotericin B (AmB) at different concentrations against Candida albicans. We applied the checkerboard assay using different concentrations of the commercial drug AmB and the synthetic peptides γ31-45PvD1++ and γ33-41PvD1++ against C. albicans, aiming to find combinations with synergistic interactions. Between these two interactions involving γ31-45PvD1++ and AmB, an additive effect was observed. One such interaction occurred at concentrations of 0.009 µM of peptide γ31-45PvD1++ and 13.23 µM of AmB and another condition of 0.019 µM of peptide γ31-45PvD1++ and 6.61 µM of AmB. The other two concentrations of the interaction showed a synergistic effect in the combination of synthetic peptide γ31-45PvD1++ and AmB, where the concentrations were 1.40 µM peptide γ31-45PvD1++ and 0.004 µM AmB and 0.70 µM γ31-45PvD1++ peptide and 0.002 µM AmB. We proceeded with analysis of the mechanism of action involving synergistic effects. This examination unveiled a range of impactful outcomes, including the impairment of mitochondrial functionality, compromise of cell wall integrity, DNA degradation, and a consequential decline in cell viability. We also observed that both synergistic combinations were capable of causing damage to the plasma membrane and cell wall, causing leakage of intracellular components. This discovery demonstrates for the first time that the synergistic combinations found between the synthetic peptide γ31-45PvD1++ and AmB have an antifungal effect against C. albicans, acting on the integrity of the plasma membrane and cell wall.

Amphotericin B in the Era of New Antifungals: Where Will It Stand?

Amphotericin B (AmB) has long stood as a cornerstone in the treatment of invasive fungal infections (IFIs), especially among immunocompromised patients. However, the landscape of antifungal therapy is evolving. New antifungal agents, boasting novel mechanisms of action and better safety profiles, are entering the scene, presenting alternatives to AmB's traditional dominance. This shift, prompted by an increase in the incidence of IFIs, the growing demographic of immunocompromised individuals, and changing patterns of fungal resistance, underscores the continuous need for effective treatments. Despite these challenges, AmB's broad efficacy and low resistance rates maintain its essential status in antifungal therapy. Innovations in AmB formulations, such as lipid complexes and liposomal delivery systems, have significantly mitigated its notorious nephrotoxicity and infusion-related reactions, thereby enhancing its clinical utility. Moreover, AmB's efficacy in treating severe and rare fungal infections and its pivotal role as prophylaxis in high-risk settings highlight its value and ongoing relevance. This review examines AmB's standing amidst the ever-changing antifungal landscape, focusing on its enduring significance in current clinical practice and exploring its potential future therapeutic adaptations.

[Impurity profile analysis of amphotericin B using on-line two-dimensional high performance liquid chromatography-quadrupole time-of-flight mass spectrometry]

Amphotericin B (AmB) is a polyene-macrolide antimicrobial drug with a broad antibacterial spectrum and remarkable efficacy against deep fungal infections. It binds to ergosterol on the fungal cell membrane and alters its permeability, thereby destroying the membrane. AmB is a multicomponent antimicrobial medication that contains a wide range of impurities, rendering quality analysis extremely difficult. In the current Chinese Pharmacopoeia (Edition 2020) and European Pharmacopoeia (EP10.3), high performance liquid chromatography (HPLC) is applied to examine related substances in AmB. However, this technique presents a number of issues. For instance, the mobile phases used in the HPLC method described in both references contain nonvolatile inorganic salts, which cannot be coupled with a mass spectrometry (MS) detector. In addition, because the mobile phases used have a low pH, the component/impurities of AmB drug can easily be degraded or interconverted during the analytical process, leading to reduced analytical accuracy. Therefore, the accuracy and sensitivity of this method must be improved. In this study, a method based on on-line two-dimensional high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (2D HPLC-Q TOF/MS) was developed to analyze the impurity profile of AmB in accordance with the Chinese Pharmacopoeia (Edition 2020) and European Pharmacopoeia (EP10.3). The method combines on-line dilution and a multiple-capture HPLC system to achieve the efficient separation of AmB component/impurities. It also resolves the issue of poor solvent compatibility in 2D HPLC, increases the analytical flux, enhances the automation capability, reduces the mutual conversion of AmB and its impurities during the analytical process, and increases the detection sensitivity of the method. MS was also used to determine the structural inference of unstable components and impurities. An XBridge Shield C18 column (250 mm×4.6 mm, 3 μm) was used for first-dimensional-liquid chromatography with gradient elution using methanol-acetonitrile-4.2 g/L citric acid monohydrate solution (10∶30∶60, v/v/v, pH 4.7) as mobile phase A and methanol-acetonitrile-4.2 g/L citric acid monohydrate solution (12∶68∶20, v/v/v, pH 3.9) as mobile phase B. An Xtimate C8 column (10 mm×2.1 mm, 5 μm) was used as the trap column, and trapping and desalting were performed using 10 mmol/L ammonium formate aqueous solution containing 0.1% formic acid-acetonitrile (95∶5, v/v). An Xtimate C8 column (250 mm×2.1 mm, 5 μm) was used for second-dimensional-liquid chromatography with gradient elution using 10 mmol/L ammonium formate aqueous solution containing 0.1% formic acid-acetonitrile (95∶5, v/v) and 10 mmol/L ammonium formate aqueous solution containing 0.1% formic acid-acetonitrile (5∶95, v/v) as mobile phases. The data were collected in positive-ion mode. In this study, the structures of six impurities in amphotericin B were inferred, according to the fragmentation, the MS and MS2 spectra of each impurity. The developed method can be used to quickly and sensitively analyze the impurity profile of AmB. Furthermore, the research results on impurity profiles can be applied to guide improvements in AmB production.

Effectiveness, Tolerability, and Safety of Different Amphotericin B Formulations in Invasive Fungal Infections: A Multicenter, Retrospective, Observational Study

PURPOSE

Data on the real-life use of amphotericin B lipid complex (ABLC) compared with other available formulations are limited. This study aimed to evaluate the effectiveness, tolerability, and safety of different amphotericin B (AMB) intravenously administered in the context of hospital practice for the treatment of invasive fungal infections (IFI) and to provide new insights into the profile of ABLC.

METHODS

This is a multicenter, retrospective, observational study conducted at 10 tertiary Brazilian hospitals. Patients first exposed to any formulation of AMB for treating endemic and opportunistic IFI who had received at least 2 intravenous doses were screened. Retrospective data (from January 2014 to December 2019) were extracted from the patients' medical records. Clinical parameters were examined pre- and post-treatment to determine effectiveness; acute infusion-related side effects (IRSE) and drug interruption to determine tolerability; and adverse events, toxicity, and treatment interruption were stated to analyze safety.

FINDINGS

Overall, 1879 medical records of patients were identified. The median (interquartile rate) duration of treatment was 14 (7-21) days. The overall success rate (95% confidence interval [CI]) was 65% (95% CI 60-65). ABLC proved to be effective among AMB formulations with 59% (95% CI 55.6-62.5) within complete response. This was significantly higher in patients who received the drug for a longer period, ≥4 weeks compared to <1 week treatment (P < 0.001). IRSE was observed in 446 (23.7%) patients. Eight cases (1.4%) of severe IRSE in pediatrics and 14 (1.1%) in adults resulted in treatment discontinuation. Regarding safety, 637 (33.9%) patients presented some alteration in creatinine levels during AMB exposure, and 89 (4.74%) had to interrupt or discontinue the drug within the first 14 days of therapy because of renal dysfunction. Overall mortality was 34%.

IMPLICATIONS

ABLC is an effective formulation for the treatment of invasive fungal infections, with few adverse events leading to drug discontinuation or lethal outcomes. Furthermore, this real-life study confirmed the comparative safety of AMB lipid formulations versus AMB deoxycholate.

Time to Think Antifungal Resistance Increased Antifungal Resistance Exacerbates the Burden of Fungal Infections Including Resistant Dermatomycoses

Increased antifungal resistance is exacerbating the burden of invasive fungal infections, as well as potentially contributing to the increase in resistant dermatomycoses. In this commentary, we focus on antifungal drug resistance, in contrast to antibacterial resistance. We provide a brief historical perspective on the emergence of antifungal resistance and propose measures for combating this growing health concern. The increase in the incidence of invasive and cutaneous fungal infections parallels advancements in medical interventions, such as immunosuppressive drugs, to manage cancer and reduce organ rejection following transplant. A disturbing relatively new trend in antifungal resistance is the observation of several fungal species that now exhibit multidrug resistance (eg, Candida auris, Trichophyton indotineae). Increasing awareness of these multidrug-resistant species is paramount. Therefore, increased education regarding potential fungus-associated infections is needed to address awareness in the general healthcare setting, which may result in a more realistic picture of the prevalence of antifungal-resistant infections. In addition to education, increased use of diagnostic tests (eg, micro and macro conventional assays or molecular testing) should be routine for healthcare providers facing an unknown fungal infection. Two critical barriers that affect the low rates for Antifungal Susceptibility Testing (AST) are low (or a lack of) sufficient insurance reimbursement rates and the low number of qualified laboratories with the capacity to perform AST. The ultimate aim is to improve the quality of patient care through fungal identification, diagnosis, and, where appropriate, susceptibility testing. Here we propose an all-encompassing call to action to address this emerging challenge.

A Cyclam Salt as an Antifungal Agent: Interference with Candida spp. and Cryptococcus neoformans Mechanisms of Virulence

The importance of fungal infections, particularly those caused by yeasts, is increasing among the medical community. Candida albicans and Cryptococcus neoformans are amongst the high-priority fungal species identified by the World Health Organization (WHO) and are considered in the critical group, while Candida krusei is included in the medium-priority group. The cyclam salt H4[H2(4-CF3PhCH2)2Cyclam]Cl4 proved to be active against the growth of these three yeasts, and the aim of this work was to verify its interference with their virulence mechanisms, whether shared or unique. H4[H2(4-CF3PhCH2)2Cyclam]Cl4 significantly inhibited biofilm production and catalase activity, being able to interfere with C. albicans dimorphic transition and C. neoformans melanin production. At the minimal inhibitory concentration (MIC) values, H4[H2(4-CF3PhCH2)2Cyclam]Cl4 had no antioxidant effect, as determined by the DPPH method. When using the RAW264.7 macrophage cell line, H4[H2(4-CF3PhCH2)2Cyclam]Cl4 reduced nitric oxide (NO) detection (the Griess reaction), but this effect was associated with a significant toxic effect on the cells.

Prevalence, treatment, and factors associated with cryptococcal meningitis post introduction of integrase inhibitors antiretroviral based regimens among People Living with HIV in Tanzania

OBJECTIVE

This study aimed to assess the prevalence of Cryptococcal Meningitis (CM), treatment practice, and the associated factors post-introduction of Tenofovir Lamivudine and Dolutegravir (TLD) regimen among People Living with HIV (PLHIV) in Tanzania.

METHODS

This was an analytical cross-sectional study, and the data was collected retrospectively in three public regional referral hospitals (RRHs) in Dar es Salaam, Tanzania. A total of 405 files of the PLHIV admitted in the medical wards on the TLD regimen from January 2019 to December 2022 were reviewed. The collected information includes the patient's demographic characteristics, Cryptococcal status, CD4 level at the time of CM diagnosis, status of using ART, CM treatment approach, and outcome. Data was analyzed using SPSS software version 23.

RESULTS

Out of 405 patients, the majority 267(65.9%) were female, 224(55.3%) were aged between 36-55 years, and 293(72.3%) were married. ART defaulters were found to be 37(9.1%). The prevalence of CM was found to be 48(11.9%), out of which 42(87.5%) received fluconazole alone. ART defaulter and marital status significantly (p-value < 0.05) were associated with those who tested CM positive.

CONCLUSION

The study found the prevalence of CM among PLHIV to be significantly high and the majority were treated with fluconazole alone. ART defaulters and marital status were significantly associated with one being CM positive. Responsible authorities and stakeholders should enforce guideline adherence and PLHIV should be encouraged on medication adherence.

Antifungal chemicals promising function in disease prevention, method of action and mechanism

The increasing use of antimicrobial drugs has been linked to the rise of drug-resistant fungus in recent years. Antimicrobial resistance is being studied from a variety of perspectives due to the important clinical implication of resistance. The processes underlying this resistance, enhanced methods for identifying resistance when it emerges, alternate treatment options for infections caused by resistant organisms, and so on are reviewed, along with strategies to prevent and regulate the formation and spread of resistance. This overview will focus on the action mechanism of antifungals and the resistance mechanisms against them. The link between antibacterial and antifungal resistance is also briefly discussed. Based on their mechanism action, antifungals are divided into three distinct categories: azoles, which target the ergosterol synthesis; 5-fluorocytosine, which targets macromolecular synthesis and polyenes, which interact physiochemically with fungal membrane sterols. Antifungal resistance can arise through a wide variety of ways. Overexpression of the target of the antifungal drug, changes to the drug target, changes to sterol biosynthesis, decreased intercellular concentration of the target enzyme, and other processes. A correlation exists between the mechanisms of resistance to antibacterial and antifungals, despite the fact that the comparison between the two is inevitably constrained by various parameters mentioned in the review. Drug extrusion via membrane pumps has been thoroughly documented in both prokaryotic and eukaryotic cells, and development of new antifungal compounds and strategies has also been well characterized.

Fungicide-tolerant persister formation during cryptococcal pulmonary infection

Bacterial persisters, a subpopulation of genetically susceptible cells that are normally dormant and tolerant to bactericides, have been studied extensively because of their clinical importance. In comparison, much less is known about the determinants underlying fungicide-tolerant fungal persister formation in vivo. Here, we report that during mouse lung infection, Cryptococcus neoformans forms persisters that are highly tolerant to amphotericin B (AmB), the standard of care for treating cryptococcosis. By exploring stationary-phase indicator molecules and developing single-cell tracking strategies, we show that in the lung, AmB persisters are enriched in cryptococcal cells that abundantly produce stationary-phase molecules. The antioxidant ergothioneine plays a specific and key role in AmB persistence, which is conserved in phylogenetically distant fungi. Furthermore, the antidepressant sertraline (SRT) shows potent activity specifically against cryptococcal AmB persisters. Our results provide evidence for and the determinant of AmB-tolerant persister formation in pulmonary cryptococcosis, which has potential clinical significance.

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.

Intra-amniotic Candida albicans Infection Treated With Liposomal Amphotericin B With a Successful Neonatal Outcome

Intra-amniotic infection with Candida species is an uncommon but severe condition with high fetal morbimortality and no established clinical guidelines for its management. We report a Candida albicans intra-amniotic infection diagnosed in a 25-week pregnant woman, successfully treated with high-dose liposomal amphotericin B. Pregnancy was prolonged until 30 weeks, and despite persistently positive Candida cultures in amniotic fluid, a healthy newborn was delivered without evidence of systemic infection. Amphotericin concentration was determined at birth, revealing levels over 30 times higher in mother's and cord blood than in the amniotic fluid, probably explaining the clinical protection despite failure in obtaining fungal clearance.

Brain glucose induces tolerance of Cryptococcus neoformans to amphotericin B during meningitis

Antibiotic tolerance is the ability of a susceptible population to survive high doses of cidal drugs and has been shown to compromise therapeutic outcomes in bacterial infections. In comparison, whether fungicide tolerance can be induced by host-derived factors during fungal diseases remains largely unknown. Here, through a systematic evaluation of metabolite-drug-fungal interactions in the leading fungal meningitis pathogen, Cryptococcus neoformans, we found that brain glucose induces fungal tolerance to amphotericin B (AmB) in mouse brain tissue and patient cerebrospinal fluid via the fungal glucose repression activator Mig1. Mig1-mediated tolerance limits treatment efficacy for cryptococcal meningitis in mice via inhibiting the synthesis of ergosterol, the target of AmB, and promoting the production of inositolphosphorylceramide, which competes with AmB for ergosterol. Furthermore, AmB combined with an inhibitor of fungal-specific inositolphosphorylceramide synthase, aureobasidin A, shows better efficacy against cryptococcal meningitis in mice than do clinically recommended therapies.

Conjugates of amphotericin B to resolve challenges associated with its delivery

INTRODUCTION

Amphotericin B (AmB), a promising antifungal and antileishmanial drug, acts on the membrane of microorganisms. The clinical use of AmB is limited due to issues associated with its delivery including poor solubility and bioavailability, instability in acidic media, poor intestinal permeability, dose and aggregation state dependent toxicity, parenteral administration, and requirement of cold chain for transport and storage, etc.

AREAS COVERED

Scientists have formulated and explored various covalent conjugates of AmB to reduce its toxicity with increase in solubility, oral bioavailability, and payload or loading of AmB by using various polymers, lipids, carbon-based nanocarriers, metallic nanoparticles, and vesicular carriers, etc. In this article, we have reviewed various conjugates of AmB with polymers and nanomaterials explored for its delivery to give a deep insight regarding further exploration in future.

EXPERT OPINION

Covalent conjugates of AmB have been investigated by scientists, and preliminary in vitro and animal investigations have given successful results, which are required to be validated further with systematic investigation on safety and therapeutic efficacy in animals followed by clinical trials.

Commensal production of a broad-spectrum and short-lived antimicrobial peptide polyene eliminates nasal Staphylococcus aureus

Antagonistic bacterial interactions often rely on antimicrobial bacteriocins, which attack only a narrow range of target bacteria. However, antimicrobials with broader activity may be advantageous. Here we identify an antimicrobial called epifadin, which is produced by nasal Staphylococcus epidermidis IVK83. It has an unprecedented architecture consisting of a non-ribosomally synthesized peptide, a polyketide component and a terminal modified amino acid moiety. Epifadin combines a wide antimicrobial target spectrum with a short life span of only a few hours. It is highly unstable under in vivo-like conditions, potentially as a means to limit collateral damage of bacterial mutualists. However, Staphylococcus aureus is eliminated by epifadin-producing S. epidermidis during co-cultivation in vitro and in vivo, indicating that epifadin-producing commensals could help prevent nasal S. aureus carriage. These insights into a microbiome-derived, previously unknown antimicrobial compound class suggest that limiting the half-life of an antimicrobial may help to balance its beneficial and detrimental activities.

Developing nanosize carrier systems for Amphotericin-B: A review on the biomedical application of nanoparticles for the treatment of leishmaniasis and fungal infections

New formulations of Amphotericin-B (Am-B), the most popular therapeutic drug for many human infections such as parasitic and fungal pathogens, are safe, economical, and effective in the world. Several newly designed carrier systems for Am-B can also be considered orally with sufficient gastrointestinal permeability and good solubility. However, the clinical application of several new formulations of Am-B with organ cytotoxicity, low bioavailability, high costs, and technical problems have caused some issues. Therefore, more attention and scientific design are required to progress safe and effective drug delivery systems. Currently, the application of nano-based technology and nanomaterials in the advancement of drug delivery systems exhibits promising outcomes to cure many human systemic infections. Designing novel drug delivery systems including solid lipid nanostructured materials, lipo-polymersomes, drug conjugates and microneedles, liposomes, polymer and protein-based nanostructured materials, dendrimers, emulsions, mixed micelles, polymeric micelles, cyclodextrins, nanocapsules, and nanocochleate for Am-B has many advantages to reducing several related issues. The unique properties of nanostructured particles such as proper morphology, small size, surface coatings, and, electrical charge, permit scientists to design new nanocomposite materials against microorganisms for application in various human diseases. These features have made these nanoparticles an ideal candidate for drug delivery systems in clinical approaches to cure a number of human disorders and currently, several therapeutic nanostructured material formulations are under different stages of clinical tests. Hence, this scientific paper mainly discussed the advances in new formulations of Am-B for the treatment of human systemic infections and related clinical tests.

Update on fungal lipid biosynthesis inhibitors as antifungal agents

Fungal diseases today represent a world-wide problem. Poor hygiene and decreased immunity are the main reasons behind the manifestation of this disease. After COVID-19, an increase in the rate of fungal infection has been observed in different countries. Different classes of antifungal agents, such as polyenes, azoles, echinocandins, and anti-metabolites, as well as their combinations, are currently employed to treat fungal diseases; these drugs are effective but can cause some side effects and toxicities. Therefore, the identification and development of newer antifungal agents is a current need. The fungal cell comprises many lipids, such as ergosterol, phospholipids, and sphingolipids. Ergosterol is a sterol lipid that is only found in fungal cells. Various pathways synthesize all these lipids, and the activities of multiple enzymes govern these pathways. Inhibiting these enzymes will ultimately impede the lipid synthesis pathway, and this phenomenon could be a potential antifungal therapy. This review will discuss various lipid synthesis pathways and multiple antifungal agents identified as having fungal lipid synthesis inhibition activity. This review will identify novel compounds that can inhibit fungal lipid synthesis, permitting researchers to direct further deep pharmacological investigation and help develop drug delivery systems for such compounds.

Mucus-Permeable Sonodynamic Therapy Mediated Amphotericin B-Loaded PEGylated PLGA Nanoparticles Enable Eradication of Candida albicans Biofilm

Background

Candida albicans (C. albicans) forms pathogenic biofilms, and the dense mucus layer secreted by the epithelium is a major barrier to the traditional antibiotic treatment of mucosa-associated C. albicans infections. Herein, we report a novel anti-biofilm strategy of mucus-permeable sonodynamic therapy (mp-SDT) based on ultrasound (US)-mediated amphotericin B-loaded PEGylated PLGA nanoparticles (AmB-NPs) to overcome mucus barrier and enable the eradication of C. albicans biofilm.

Methods

AmB-NPs were fabricated using ultrasonic double emulsion method, and their physicochemical and sonodynamic properties were determined. The mucus and biofilm permeability of US-mediated AmB-NPs were further investigated. Moreover, the anti-biofilm effect of US-mediated AmB-NPs treatment was thoroughly evaluated on mucus barrier abiotic biofilm, epithelium-associated biotic biofilm, and C. albicans-induced rabbit vaginal biofilms model. In addition, the ultrastructure and secreted cytokines of epithelial cells and the polarization of macrophages were analyzed to investigate the regulation of local cellular immune function by US-mediated AmB-NPs treatment.

Results

Polymeric AmB-NPs display excellent sonodynamic performance with massive singlet oxygen (1O2) generation. US-mediated AmB-NPs could rapidly transport through mucus and promote permeability in biofilms, which exhibited excellent eradicating ability to C. albicans biofilms. Furthermore, in the vaginal epithelial cells (VECs)-associated C. albicans biofilm model, the mp-SDT scheme showed the strongest biofilm eradication effect, with up to 98% biofilm re-formation inhibition rate, improved the ultrastructural damage, promoted local immune defense enhancement of VECs, and regulated the polarization of macrophages to the M1 phenotype to enhance macrophage-associated antifungal immune responses. In addition, mp-SDT treatment exhibited excellent therapeutic efficacy against C. albicans-induced rabbit vaginitis, promoted the recovery of mucosal epithelial ultrastructure, and contributed to the reshaping of a healthier vaginal microbiome.

Conclusion

The synergistic anti-biofilm strategies of mp-SDT effectively eradicated C. albicans biofilm and simultaneously regulated local antifungal immunity enhancement, which may provide a new approach to treat refractory drug-resistant biofilm-associated mucosal candidiasis.

Solid Dispersion Incorporated into Dissolving Microneedles for Improved Antifungal Activity of Amphotericin B: In Vivo Study in a Fungal Keratitis Model

Fungal keratitis (FK) is a fungal infection of the cornea, which is part of the eye and causes corneal ulcers and an increased risk of permanent blindness, which is often found in Candida albicans species. Amphotericin B (AMB), which is a group of polyenes as the first-line treatment of FK, is effective in annihilating C. albicans. However, AMB preparations such as eye drops and ointments have major drawbacks, for instance, requiring more frequent administrations, loss of the drug by the drainage process, and rapid elimination in the precornea, which result in low bioavailability of the drug. An ocular dissolving microneedle containing the solid dispersion amphotericin B (DMN-SD-AMB) had been developed using a mixture of poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) polymers, while the solid dispersion AMB (SD-AMB) was contained in the needle as a drug. This study aims to determine the most optimal and safest DMN-SD-AMB formula for the treatment of FK in the eye as well as a solution to overcome the low bioavailability of AMB eye drops and ointment preparations. SD-AMB had been successfully developed, which was characterized by increased antifungal activity and drug release in vitro compared to other treatments. Furthermore, DMN-SD-AMB studies had also been successfully performed with the best formulation, which exhibited the best ex vivo corneal permeation profile and antifungal activity as well as being safe from eye irritation. In addition, an in vivo antifungal activity using a rabbit infection model shows that the number of fungal colonies was 0.98 ± 0.11 log10 CFU/mL (F3), 5.76 ± 0.32 log10 CFU/mL (AMB eye drops), 4.01 ± 0.28 log10 CFU/mL (AMB ointments), and 9.09 ± 0.65 log10 CFU/mL (control), which differed significantly (p < 0.05). All of these results evidence that DMN-SD-AMB is a new approach to developing intraocular preparations for the treatment of FK.

In vitro susceptibility to miltefosine of amphotericin B-resistant Leishmania (Mundinia) martiniquensis

Leishmania (Mundinia) martiniquensis is a newly described species that causes human visceral, disseminated, and mucocutaneous leishmaniases. Amphotericin B deoxycholate (AmpB) is the first-line drug for the treatment of leishmaniasis in Thailand; however, several relapse cases of leishmaniasis caused by L. martiniquensis have been documented. In this study, in vitro susceptibility to AmpB and miltefosine (MIL) of wild-type (before treatment, LSCM1) and two AmpB-resistant L. martiniquensis strains (an in vitro-induced AmpB-resistant strain, AmpBRP2i, and a relapse strain, LSCM1-6) were determined. Results reveal that the IC50 value and resistance index against both drugs of promastigotes and intracellular amastigotes of the AmpBRP2i and LSCM1-6 strains were statistically significantly higher than those of the LSCM1 strain suggesting that cross-resistance with MIL occurred in both AmpB-resistant strains. The results of this study advocate further investigation into mechanisms that involve the complex nature of AmpB/MIL resistance in L. martiniquensis and development of effective methods for the identification of the AmpB-resistant parasites to help delivery of appropriate treatments for patients and for epidemiological surveys to survey the potential spread of drug-resistant strains.

Prevention and management of antibiotic associated acute kidney injury in critically ill patients: new insights

PURPOSE OF REVIEW

Drug associated kidney injury (D-AKI) occurs in 19-26% of hospitalized patients and ranks as the third to fifth leading cause of acute kidney injury (AKI) in the intensive care unit (ICU). Given the high use of antimicrobials in the ICU and the emergence of new resistant organisms, the implementation of preventive measures to reduce the incidence of D-AKI has become increasingly important.

RECENT FINDINGS

Artificial intelligence is showcasing its capabilities in early recognition of at-risk patients for acquiring AKI. Furthermore, novel synthetic medications and formulations have demonstrated reduced nephrotoxicity compared to their traditional counterparts in animal models and/or limited clinical evaluations, offering promise in the prevention of D-AKI. Nephroprotective antioxidant agents have had limited translation from animal studies to clinical practice. The control of modifiable risk factors remains pivotal in avoiding D-AKI.

SUMMARY

The use of both old and new antimicrobials is increasingly important in combating the rise of resistant organisms. Advances in technology, such as artificial intelligence, and alternative formulations of traditional antimicrobials offer promise in reducing the incidence of D-AKI, while antioxidant medications may aid in minimizing nephrotoxicity. However, maintaining haemodynamic stability using isotonic fluids, drug monitoring, and reducing nephrotoxic burden combined with vigilant antimicrobial stewardship remain the core preventive measures for mitigating D-AKI while optimizing effective antimicrobial therapy.

Enhancing the Antifungal Efficacy of Fluconazole with a Diterpene: Abietic Acid as a Promising Adjuvant to Combat Antifungal Resistance in Candida spp

The increasing antifungal resistance rates against conventional drugs reveal the urgent need to search for new therapeutic alternatives. In this context, natural bioactive compounds have a critical role in antifungal drug development. Since evidence demonstrates that abietic acid, a diterpene found in Pinus species, has significant antimicrobial properties, this study aimed to evaluate the antifungal activity of abietic acid against Candida spp and its ability to potentiate the activity of fluconazole. Abietic acid was tested both individually and in combination with fluconazole against Candida albicans (CA INCQS 40006), Candida krusei (CK INCQS 40095), and Candida tropicalis (CT INCQS 40042). The microdilution method was used to determine the IC50 and the cell viability curve. Minimum Fungicidal Concentration (MFC) was determined by subculture in a solid medium. The plasma membrane permeability was measured using a fluorescent SYTOX Green probe. While the IC50 of the drugs alone ranged between 1065 and 3255 μg/mL, the IC50 resulting from the combination of abietic acid and fluconazole ranged between 7563 and 160.1 μg/mL. Whether used in combination with fluconazole or isolated, abietic acid exhibited Minimum Fungicidal Concentration (MFC) values exceeding 1024 μg/mL against Candida albicans, Candida krusei and Candida tropicalis. However, it was observed that the antifungal effect of fluconazole was enhanced when used in combination with abietic acid against Candida albicans and Candida tropicalis. These findings suggest that while abietic acid alone has limited inherent antifungal activity, it can enhance the effectiveness of fluconazole, thereby reducing antifungal resistance.

Inorganic Nanoparticles: Tools to Emphasize the Janus Face of Amphotericin B

Amphotericin B is the oldest antifungal molecule which is still currently widely used in clinical practice, in particular for the treatment of invasive diseases, even though it is not devoid of side effects (particularly nephrotoxicity). Recently, its redox properties (i.e., both prooxidant and antioxidant) have been highlighted in the literature as mechanisms involved in both its activity and its toxicity. Interestingly, similar properties can be described for inorganic nanoparticles. In the first part of the present review, the redox properties of Amphotericin B and inorganic nanoparticles are discussed. Then, in the second part, inorganic nanoparticles as carriers of the drug are described. A special emphasis is given to their combined redox properties acting either as a prooxidant or as an antioxidant and their connection to the activity against pathogens (i.e., fungi, parasites, and yeasts) and to their toxicity. In a majority of the published studies, inorganic nanoparticles carrying Amphotericin B are described as having a synergistic activity directly related to the rupture of the redox homeostasis of the pathogen. Due to the unique properties of inorganic nanoparticles (e.g., magnetism, intrinsic anti-infectious properties, stimuli-triggered responses, etc.), these nanomaterials may represent a new generation of medicine that can synergistically enhance the antimicrobial properties of Amphotericin B.

Safety and usefulness of nebulized liposomal amphotericin B: Systematic scoping review

PURPOSE

Invasive fungal infections potentially result in fatal outcomes in immunocompromised hosts. Compared to intravenous administration, a nebulization therapy can achieve a high concentration of drug delivered in the respiratory tract, without a systematic absorption. We herein summarized the study findings on the safety and clinical utility of nebulized liposomal amphotericin B therapy.

METHODS

According to the PRISMA Extension for Scoping Reviews, we performed a search on MEDLINE and EMBASE for articles with relevant keywords, including "inhaled liposomal amphotericin B″, "nebulized liposomal amphotericin B″, or "aerosolized liposomal amphotericin B″, from the inception of these databases to August 31, 2022.

RESULTS

Of the 172 articles found, 27 articles, including 13 case reports, 11 observational studies, and 3 clinical trials, were selected. Generally, findings showed that nebulized liposomal amphotericin B treatment appeared to be safe and without severe adverse effects. We found an accumulated evidence for the safety, tolerability, and effectiveness of nebulized liposomal amphotericin B prophylaxis among lung transplantation recipients; however, a randomized controlled study has yet to be reported. Data on hemato-oncological patients are relatively scarce; however, a randomized controlled study suggested the prophylactic effect of nebulized liposomal amphotericin B on invasive pulmonary aspergillosis. Observational and randomized controlled studies to evaluate therapeutic efficacy of the nebulized liposomal amphotericin B therapy have not been performed.

CONCLUSION

In conclusion, we found increasing evidence for the effectiveness of the inhalation therapy among patients after lung transplantation and with hemato-oncological diseases.

Recent developments in membrane targeting antifungal agents to mitigate antifungal resistance

Fungal infections cause severe and life-threatening complications especially in immunocompromised individuals. Antifungals targeting cellular machinery and cell membranes including azoles are used in clinical practice to manage topical to systemic fungal infections. However, continuous exposure to clinically used antifungal agents in managing the fungal infections results in the development of multi-drug resistance via adapting different kinds of intrinsic and extrinsic mechanisms. The unique chemical composition of fungal membranes presents attractive targets for antifungal drug discovery as it is difficult for fungal cells to modify the membrane targets for emergence of drug resistance. Here, we discussed available antifungal drugs with their detailed mechanism of action and described different antifungal resistance mechanisms. We further emphasized structure-activity relationship studies of membrane-targeting antifungal agents, and classified membrane-targeting antifungal agents on the basis of their core scaffold with detailed pharmacological properties. This review aims to pique the interest of potential researchers who could explore this interesting and intricate fungal realm.