The Echinocandins

Gene expression screening and cell factory engineering for enhancing echinocandin B production in Aspergillus nidulans NRRL8112

BACKGROUND

Echinocandin B (ECB) is a key precursor of the antifungal drug anidulafungin and its biosynthesis occurs via ani gene cluster in Aspergillus nidulans NRRL8112. Strain improvement for industrial ECB production has mainly relied on mutation breeding due to the lack of genetic tools.

RESULTS

Here, a CRISPR-base-editing tool was developed in A. nidulans NRRL8112 for simultaneous inactivation of the nkuA gene and two marker genes, pryoA and riboB, which enabled efficient genetic manipulation. Then, in-vivo plasmid assembly was harnessed for ani gene expression screening, identifying the rate-limiting enzyme AniA and a pathway-specific transcription factor AniJ. Stepwise titer enhancement was achieved by overexpressing aniA and/or aniJ, and ECB production reached 1.5 g/L during 5-L fed-batch fermentation, an increase of ~ 30-fold compared with the parent strain.

CONCLUSION

This study, for the first time, revealed the regulatory mechanism of ECB biosynthesis and harnessed genetic engineering for the development of an efficient ECB-producing strain.

Resistance Mechanisms of Plant Pathogenic Fungi to Fungicide, Environmental Impacts of Fungicides, and Sustainable Solutions

The significant reduction in agricultural output and the decline in product quality are two of the most glaring negative impacts caused by plant pathogenic fungi (PPF). Furthermore, contaminated food or transit might introduce mycotoxins produced by PPF directly into the food chain. Eating food tainted with mycotoxin is extremely dangerous for both human and animal health. Using fungicides is the first choice to control PPF or their toxins in food. Fungicide resistance and its effects on the environment and public health are becoming more and more of a concern, despite the fact that chemical fungicides are used to limit PPF toxicity and control growth in crops. Fungicides induce target site alteration and efflux pump activation, and mutations in PPF result in resistance. As a result, global trends are shifting away from chemically manufactured pesticides and toward managing fungal plant diseases using various biocontrol techniques, tactics, and approaches. However, surveillance programs to monitor fungicide resistance and their environmental impact are much fewer compared to bacterial antibiotic resistance surveillance programs. In this review, we discuss the PPF that contributes to disease development in plants, the fungicides used against them, factors causing the spread of PPF and the emergence of new strains, the antifungal resistance mechanisms of PPF, health, the environmental impacts of fungicides, and the use of biocontrol agents (BCAs), antimicrobial peptides (AMPs), and nanotechnologies to control PPF as a safe and eco-friendly alternative to fungicides.

Invasive fungal infections in critically ill children: epidemiology, risk factors and antifungal drugs

Background

Invasive fungal infections (IFIs) are important infectious complications amongst critically ill children. The most common fungal infections are due to Candida species. Aspergillus, Zygomycetes and Fusarium are also emerging because of the empirical use of antifungal drugs. This updated review discusses the epidemiology of IFIs as well as antifungal drugs, dosing and potential adverse effects in critically ill children.

Methods

A PubMed search was conducted with Clinical Queries using the key terms "antifungal", "children", "critical care" AND "paediatric intensive care unit" OR "PICU". The search strategy included clinical trials, randomized controlled trials, meta-analyses, observational studies and reviews and was limited to the English literature in paediatrics.

Results

Candida and Aspergillus spp. are the most prevalent fungi in paediatric IFIs, causing invasive candidiasis infections (ICIs) and invasive aspergillosis infections (IAIs), respectively. These IFIs are associated with high morbidity, mortality and healthcare costs. Candida albicans is the principal Candida spp. associated with paediatric ICIs. The risks and epidemiology for IFIs vary if considering previously healthy children treated in the paediatric intensive care unit or children with leukaemia, malignancy or a severe haematological disease. The mortality rate for IAIs in children is 2.5-3.5-fold higher than for ICIs. Four major classes of antifungals for critically ill children are azoles, polyenes, antifungal antimetabolites and echinocandins.

Conclusions

Antifungal agents are highly efficacious. For successful treatment outcomes, it is crucial to determine the optimal dosage, monitor pharmacokinetics parameters and adverse effects, and individualized therapeutic monitoring. Despite potent antifungal medications, ICIs and IAIs continue to be serious infections with high mortality rates. Pre-emptive therapy has been used for IAIs. Most guidelines recommend voriconazole as initial therapy of invasive aspergillosis in most patients, with consideration of combination therapy with voriconazole plus an echinocandin in selected patients with severe disease. The challenge is to identify critically ill patients at high risks of ICIs for targeted prophylaxis. Intravenous/per os fluconazole is first-line pre-emptive treatment for Candida spp. whereas intravenous micafungin or intravenous liposomal amphotericin B is alternative pre-emptive treatment.This article is part of the Challenges and strategies in the management of invasive fungal infections Special Issue: https://www.drugsincontext.com/special_issues/challenges-and-strategies-in-the-management-of-invasive-fungal-infections.

Candida albicans skin infection in diabetic patients: An updated review of pathogenesis and management

Candida species, commensal residents of human skin, are recognized as the cause of cutaneous candidiasis across various body surfaces. Individuals with weakened immune systems, particularly those with immunosuppressive conditions, are significantly more susceptible to this infection. Diabetes mellitus, a major metabolic disorder, has emerged as a critical factor inducing immunosuppression, thereby facilitating Candida colonization and subsequent skin infections. This comprehensive review examines the prevalence of different types of Candida albicans-induced cutaneous candidiasis in diabetic patients. It explores the underlying mechanisms of pathogenicity and offers insights into recommended preventive measures and treatment strategies. Diabetes notably increases vulnerability to oral and oesophageal candidiasis. Additionally, it can precipitate vulvovaginal candidiasis in females, Candida balanitis in males, and diaper candidiasis in young children with diabetes. Diabetic individuals may also experience candidal infections on their nails, hands and feet. Notably, diabetes appears to be a risk factor for intertrigo syndrome in obese individuals and periodontal disorders in denture wearers. In conclusion, the intricate relationship between diabetes and cutaneous candidiasis necessitates a comprehensive understanding to strategize effective management planning. Further investigation and interdisciplinary collaborative efforts are crucial to address this multifaceted challenge and uncover novel approaches for the treatment, management and prevention of both health conditions, including the development of safer and more effective antifungal agents.

Drug repurposing for fungal infections

The rise of multidrug-resistant bacteria is a well-recognized threat to world health, necessitating the implementation of effective treatments. This issue has been identified as a top priority on the global agenda by the World Health Organization. Certain strains, such as Candida glabrata, Candida krusei, Candida lusitaniae, Candida auris, select cryptococcal species, and opportunistic Aspergillus or Fusarium species, have significant intrinsic resistance to numerous antifungal medicines. This inherent resistance and subsequent suboptimal clinical outcomes underscore the critical imperative for enhanced therapeutic alternatives and management protocols. The challenge of effectively treating fungal infections, compounded by the protracted timelines involved in developing novel drugs, underscores the pressing need to explore alternative therapeutic avenues. Among these, drug repurposing emerges as a particularly promising and expeditious solution, providing cost-effective solutions and safety benefits. In the fight against life-threatening resistant fungal infections, the idea of repurposing existing medications has encouraged research into both established and new compounds as a last-resort therapy. This chapter seeks to provide a comprehensive overview of contemporary antifungal drugs, as well as their key resistance mechanisms. Additionally, it seeks to provide insight into the antimicrobial properties of non-traditional drugs, thereby offering a holistic perspective on the evolving landscape of antifungal therapeutics.

Microbial lipopeptides: their pharmaceutical and biotechnological potential, applications, and way forward

As lead molecules, cyclic lipopeptides with antibacterial, antifungal, and antiviral properties have garnered a lot of attention in recent years. Because of their potential, cyclic lipopeptides have earned recognition as a significant class of antimicrobial compounds with applications in pharmacology and biotechnology. These lipopeptides, often with biosurfactant properties, are amphiphilic, consisting of a hydrophilic moiety, like a carboxyl group, peptide backbone, or carbohydrates, and a hydrophobic moiety, mostly a fatty acid. Besides, several lipopeptides also have cationic groups that play an important role in biological activities. Antimicrobial lipopeptides can be considered as possible substitutes for antibiotics that are conventional to address the current drug-resistant issues as pharmaceutical industries modify the parent antibiotic molecules to render them more effective against antibiotic-resistant bacteria and fungi, leading to the development of more resistant microbial strains. Bacillus species produce lipopeptides, which are secondary metabolites that are amphiphilic and are typically synthesized by non-ribosomal peptide synthetases (NRPSs). They have been identified as potential biocontrol agents as they exhibit a broad spectrum of antimicrobial activity. A further benefit of lipopeptides is that they can be produced and purified biotechnologically or biochemically in a sustainable manner using readily available, affordable, renewable sources without harming the environment. In this review, we discuss the biochemical and functional characterization of antifungal lipopeptides, as well as their various modes of action, method of production and purification (in brief), and potential applications as novel antibiotic agents.

Candida albicans exhibits heterogeneous and adaptive cytoprotective responses to antifungal compounds

Candida albicans, an opportunistic human pathogen, poses a significant threat to human health and is associated with significant socio-economic burden. Current antifungal treatments fail, at least in part, because C. albicans can initiate a strong drug tolerance response that allows some cells to grow at drug concentrations above their minimal inhibitory concentration. To better characterize this cytoprotective tolerance program at the molecular single-cell level, we used a nanoliter droplet-based transcriptomics platform to profile thousands of individual fungal cells and establish their subpopulation characteristics in the absence and presence of antifungal drugs. Profiles of untreated cells exhibit heterogeneous expression that correlates with cell cycle stage with distinct metabolic and stress responses. At 2 days post-fluconazole exposure (a time when tolerance is measurable), surviving cells bifurcate into two major subpopulations: one characterized by the upregulation of genes encoding ribosomal proteins, rRNA processing machinery, and mitochondrial cellular respiration capacity, termed the Ribo-dominant (Rd) state; and the other enriched for genes encoding stress responses and related processes, termed the Stress-dominant (Sd) state. This bifurcation persists at 3 and 6 days post-treatment. We provide evidence that the ribosome assembly stress response (RASTR) is activated in these subpopulations and may facilitate cell survival.

Treatment of Invasive Aspergillosis: How It's Going, Where It's Heading

Despite improvements in treatment and diagnostics over the last two decades, invasive aspergillosis (IA) remains a devastating fungal disease. The number of immunocompromised patients and hence vulnerable hosts increases, which is paralleled by the emergence of a rise in IA cases. Increased frequencies of azole-resistant strains are reported from six continents, presenting a new challenge for the therapeutic management. Treatment options for IA currently consist of three classes of antifungals (azoles, polyenes, echinocandins) with distinctive advantages and shortcomings. Especially in settings of difficult to treat IA, comprising drug tolerance/resistance, limiting drug-drug interactions, and/or severe underlying organ dysfunction, novel approaches are urgently needed. Promising new drugs for the treatment of IA are in late-stage clinical development, including olorofim (a dihydroorotate dehydrogenase inhibitor), fosmanogepix (a Gwt1 enzyme inhibitor), ibrexafungerp (a triterpenoid), opelconazole (an azole optimized for inhalation) and rezafungin (an echinocandin with long half-life time). Further, new insights in the pathophysiology of IA yielding immunotherapy as a potential add-on therapy. Current investigations show encouraging results, so far mostly in preclinical settings. In this review we discuss current treatment strategies, give an outlook on possible new pharmaceutical therapeutic options, and, lastly, provide an overview of the ongoing research in immunotherapy for IA.

The in vitro Activity of Echinocandins Against Clinical Trichophyton rubrum Isolates and Review of the Susceptibility of T. rubrum to Echinocandins Worldwide

Introduction

The emergence of resistance in Trichophyton rubrum to azoles and terbinafine has become increasingly evident in recent years, necessitating the development of novel antifungal drugs and the exploration of new indications for existing agents.

Methods

In this study, we retrospectively evaluated the in vitro antifungal activity of 3 echinocandins (anidulafungin, caspofungin, and micafungin) against 73 clinical isolates of T. rubrum collected from a teaching hospital in Shanghai, China, using EUCAST E.DEF 9.3.1 with minor modification. We also reviewed the susceptibility of T. rubrum to echinocandins globally by literature searching.

Results

Our findings revealed that micafungin exhibited the lowest modal minimum effective concentration (MEC) value (0.08 mg/L, n = 28) and the lowest geometric mean (GM) MEC value (0.014 mg/L) among the 73 isolates of T. rubrum tested, followed by anidulafungin with a modal MEC value of 0.016 mg/L (n = 67) and a GM of 0.018 mg/L. Caspofungin displayed a higher modal MEC value of 0.5 mg/L (n = 35) and a GM of 0.308 mg/L. Despite variations in methodologies, similar results were obtained from the review of five relevant studies included in our analysis.

Discussion

Echinocandins exhibited excellent in vitro activity against T. rubrum isolates, with micafungin and anidulafungin demonstrating greater potency than caspofungin. These findings suggest that echinocandins could be considered as potential treatment options for managing recalcitrant dermatophytoses resulting from the emergence of resistance. However, it is important to note that the clinical efficacy of these in vitro findings has yet to be established and warrants further investigation.

Post-transcriptional control of antifungal resistance in human fungal pathogens

Global estimates suggest that over 300 million individuals of all ages are affected by serious fungal infections every year, culminating in about 1.7 million deaths. The societal and economic burden on the public health sector due to opportunistic fungal pathogens is quite significant, especially among immunocompromised patients. Despite the high clinical significance of these infectious agents, treatment options are limited with only three major classes of antifungal drugs approved for use. Clinical management of fungal diseases is further compromised by the emergence of antifungal resistant strains. Transcriptional and genetic mechanisms that control drug resistance in human fungal pathogens are well-studied and include drug target alteration, upregulation of drug efflux pumps as well as changes in drug affinity and abundance of target proteins. In this review, we highlight several recently discovered novel post-transcriptional mechanisms that control antifungal resistance, which involve regulation at the translational, post-translational, epigenetic, and mRNA stability levels. The discovery of many of these novel mechanisms has opened new avenues for the development of more effective antifungal treatment strategies and new insights, perspectives, and future directions that will facilitate this process are discussed.

Salvage Treatment for Invasive Aspergillosis and Mucormycosis: Challenges, Recommendations and Future Considerations

Invasive mold diseases are devastating systemic infections which demand meticulous care in selection, dosing, and therapy monitoring of antifungal drugs. Various circumstances regarding PK/PD properties of the applied drug, resistance/tolerance of the causative pathogen or host intolerability can lead to failure of the initial antifungal therapy. This necessitates treatment adaption in the sense of switching antifungal drug class or potentially adding another drug for a combination therapy approach. In the current state of drastically limited options of antifungal drug classes adaption of therapy remains challenging. Current guidelines provide restricted recommendations only and emphasize individual approaches. However, novel antifungals, incorporating innovative mechanisms of action, show promising results in late stage clinical development. These will expand options for salvage therapy in the future potentially as monotherapy or in combination with conventional or other novel antifungals. We outline current recommendations for salvage therapy including PK/PD considerations as well as elucidate possible future treatment options for invasive aspergillosis and mucormycosis.

Similarities and Differences among Species Closely Related to Candida albicans: C. tropicalis, C. dubliniensis, and C. auris

Although Candida species are widespread commensals of the microflora of healthy individuals, they are also among the most important human fungal pathogens that under certain conditions can cause diseases (candidiases) of varying severity ranging from mild superficial infections of the mucous membranes to life-threatening systemic infections. So far, the vast majority of research aimed at understanding the molecular basis of pathogenesis has been focused on the most common species—Candida albicans. Meanwhile, other closely related species belonging to the CTG clade, namely, Candida tropicalis and Candida dubliniensis, are becoming more important in clinical practice, as well as a relatively newly identified species, Candida auris. Despite the close relationship of these microorganisms, it seems that in the course of evolution, they have developed distinct biochemical, metabolic, and physiological adaptations, which they use to fit to commensal niches and achieve full virulence. Therefore, in this review, we describe the current knowledge on C. tropicalis, C. dubliniensis, and C. auris virulence factors, the formation of a mixed species biofilm and mutual communication, the environmental stress response and related changes in fungal cell metabolism, and the effect of pathogens on host defense response and susceptibility to antifungal agents used, highlighting differences with respect to C. albicans. Special attention is paid to common diagnostic problems resulting from similarities between these species and the emergence of drug resistance mechanisms. Understanding the different strategies to achieve virulence, used by important opportunistic pathogens of the genus Candida, is essential for proper diagnosis and treatment.

Echinocandins - structure, mechanism of action and use in antifungal therapy

With increasing number of immunocompromised patients as well as drug resistance in fungi, the risk of fatal fungal infections in humans increases as well. The action of echinocandins is based on the inhibition of β-(1,3)-d-glucan synthesis that builds the fungal cell wall. Caspofungin, micafungin, anidulafungin and rezafungin are semi-synthetic cyclic lipopeptides. Their specific chemical structure possess a potential to obtain novel derivatives with better pharmacological properties resulting in more effective treatment, especially in infections caused by Candida and Aspergillus species. In this review we summarise information about echinocandins with closer look on their chemical structure, mechanism of action, drug resistance and usage in clinical practice. We also introduce actual trends in modification of this antifungals as well as new methods of their administration, and additional use in viral and bacterial infections.

Study of antifungal agent caspofungin adsorption to laboratory materials

Treatment of invasive fungal infections with Caspofungin is used as the first-line antifungal agents. The minimum inhibitory concentration value is a test which indicates the degree of sensitivity of a strain regarding a drug. However, no value of minimum inhibitory concentration for caspofungin is available because very variable value is obtained. In this work, we study the link with the adsorption phenomenon of CSF previously described in literature and the lack of minimum inhibitory concentration value. A systematic study of the impact of different parameters on CSF adsorption is reported. The effect of the nature of container material, the aqueous solution pH and the organic solvent proportion was studied. In addition, the possibility of using a coating agent to minimize the adsorption was assayed and evaluated. Results obtained showed the importance of the material used during the manipulation of CSF. The use of acidic pH aqueous solution or the addition of acetonitrile or methanol proportions (50 % and 70 %, respectively) were found efficient to avoid adsorption of CSF on glassware material, which is the relevant strategy for analytical samples of caspofungin. The treatment of HPLC glass vials and 96-well plates with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane reduced the adsorption. The significant adsorption observed in this work especially with plastic materials, questions the results obtained before in different assays and explained the absence of MIC value.

Epidemiological Characterization of Clinical Fungal Isolates from Pauls Stradinš Clinical University Hospital, Latvia: A 4-Year Surveillance Report

Nosocomial fungal infections are an emerging global public health threat that requires urgent attention and proper management. With the limited availability of treatment options, it has become necessary to understand the emerging epidemiological trends, mechanisms, and risk factors. However, very limited surveillance reports are available in the Latvian and broader European context. We therefore conducted a retrospective analysis of laboratory data (2017-2020) from Pauls Stradinš Clinical University Hospital (PSCUH), Riga, Latvia, which is one of the largest public multispecialty hospitals in Latvia. A total of 2278 fungal isolates were analyzed during the study period, with Candida spp. comprising 95% of the isolates, followed by Aspergillus spp. and Geotrichum spp. Amongst the Candida spp., C. albicans and C. glabrata made up about 75% of the isolates. The Department of Lung Diseases and Thoracic Surgery had the highest caseload followed by Intensive Care Department. Majority of the fungal isolates were collected from the bronchoalveolar lavage (37%), followed by urine (19%) and sputum (18%) samples. A total of 34 cases of candidemia were noted during the study period with C. albicans being the most common candidemia pathogen. Proper surveillance of emerging epidemiological trends serve as the most reliable and powerful cornerstone towards tackling this emerging threat.

Antimycotic Drugs and their Mechanisms of Resistance to Candida Species

Fungal infections have shown an upsurge in recent decades, which is mainly because of the increasing number of immunocompromised patients and the occurrence of invasive candidiasis has been found to be 7-15 fold greater than that of invasive aspergillosis. The genus Candida comprises more than 150 distinct species, however, only a few of them are found to be pathogenic to humans. Mortality rates of Candida species are found to be around 45% and the reasons for this intensified mortality are inefficient diagnostic techniques and unfitting initial treatment strategies. There are only a few antifungal drug classes that are employed for the remedy of invasive fungal infections. which include azoles, polyenes, echinocandins, and pyrimidine analogs. During the last 2-3 decades, the usage of antifungal drugs has increased several folds due to which the reports of escalating antifungal drug resistance have also been recorded. The resistance is mostly to the triazole- based compounds. Due to the occurrence of antifungal drug resistance, the success rates of treatment have been reduced as well as major changes have been observed in the frequency of fungal infections. In this review, we have summarized the major molecular mechanisms for the development of antifungal drug resistance.

Cation Transporters of Candida albicans-New Targets to Fight Candidiasis?

Candidiasis is the wide-spread fungal infection caused by numerous strains of yeast, with the prevalence of Candida albicans. The current treatment of candidiasis is becoming rather ineffective and costly owing to the emergence of resistant strains; hence, the exploration of new possible drug targets is necessary. The most promising route is the development of novel antibiotics targeting this pathogen. In this review, we summarize such candidates found in C. albicans and those involved in the transport of (metal) cations, as the latter are essential for numerous processes within the cell; hence, disruption of their fluxes can be fatal for C. albicans.

A Candida parapsilosis Overexpression Collection Reveals Genes Required for Pathogenesis

Relative to the vast data regarding the virulence mechanisms of Candida albicans, there is limited knowledge on the emerging opportunistic human pathogen Candida parapsilosis. The aim of this study was to generate and characterize an overexpression mutant collection to identify and explore virulence factors in C. parapsilosis. With the obtained mutants, we investigated stress tolerance, morphology switch, biofilm formation, phagocytosis, and in vivo virulence in Galleria mellonella larvae and mouse models. In order to evaluate the results, we compared the data from the C. parapsilosis overexpression collection analysis to the results derived from previous deletion mutant library characterizations. Of the 37 overexpression C. parapsilosis mutants, we identified eight with altered phenotypes compared to the controls. This work is the first report to identify CPAR2_107240, CPAR2_108840, CPAR2_302400, CPAR2_406400, and CPAR2_602820 as contributors to C. parapsilosis virulence by regulating functions associated with host-pathogen interactions and biofilm formation. Our findings also confirmed the role of CPAR2_109520, CPAR2_200040, and CPAR2_500180 in pathogenesis. This study was the first attempt to use an overexpression strategy to systematically assess gene function in C. parapsilosis, and our results demonstrate that this approach is effective for such investigations.

Semi-synthetic puwainaphycin/minutissamide cyclic lipopeptides with improved antifungal activity and limited cytotoxicity

Microbial cyclic lipopeptides are an important class of antifungal compounds with applications in pharmacology and biotechnology. However, the cytotoxicity of many cyclic lipopeptides limits their potential as antifungal drugs. Here we present a structure–activity relationship study on the puwainaphycin/minutissamide (PUW/MIN) family of cyclic lipopeptides isolated from cyanobacteria. PUWs/MINs with variable fatty acid chain lengths differed in the dynamic of their cytotoxic effect despite their similar IC₅₀ after 48 hours (2.8 μM for MIN A and 3.2 μM for PUW F). Furthermore, they exhibited different antifungal potency with the lowest MIC values obtained for MIN A and PUW F against the facultative human pathogen Aspergillus fumigatus (37 μM) and the plant pathogen Alternaria alternata (0.6 μM), respectively. We used a Grignard-reaction with alkylmagnesium halides to lengthen the lipopeptide FA moiety as well as the Steglich esterification on the free hydroxyl substituents to prepare semi-synthetic lipopeptide variants possessing multiple fatty acid tails. Cyclic lipopeptides with extended and branched FA tails showed improved strain-specific antifungal activity against A. fumigatus (MIC = 0.5–3.8 μM) and A. alternata (MIC = 0.1–0.5 μM), but with partial retention of the cytotoxic effect (∼10–20 μM). However, lipopeptides with esterified free hydroxyl groups possessed substantially higher antifungal potencies, especially against A. alternata (MIC = 0.2–0.6 μM), and greatly reduced or abolished cytotoxic activity (>20 μM). Our findings pave the way for a generation of semi-synthetic variants of lipopeptides with improved and selective antifungal activities.

Both the substitution of free hydroxyl substituents and extending/branching of the fatty acid moiety improved the antifungal potency and limits the cytotoxicity of cyanobacterial cyclic lipopeptides puwainaphycin/minutissamides.

Effects of antifungal drugs on the plasma concentrations and dosage of tacrolimus in kidney transplant patients

OBJECTIVES

Tacrolimus is one of the three basic immunosuppressants used following kidney transplantation, and its plasma concentration is susceptible to antifungal drugs. Abnormal tacrolimus concentrations may lead to adverse outcomes for patients. Adjustment of the tacrolimus dose after administering antifungal drugs to patients with fungal infection after transplantations therefore has important clinical significance. Our objective is to measure the impact of antifungal drugs on the plasma concentration of tacrolimus in kidney transplant patients.

METHODS

A retrospective study was carried out in 109 kidney transplant recipients treated with a tacrolimus-based regimen and antifungal drugs simultaneously. Tacrolimus levels and dosage requirements were compared before and during antifungal therapy.

RESULTS

The plasma levels of tacrolimus were significantly increased after the combination with voriconazole and fluconazole (p<0.05). Consequently, the daily dose of tacrolimus was significantly reduced after the combination (p<0.05). However, although the tacrolimus concentration was significantly decreased after the administration of caspofungin (p<0.05), no apparent change in the daily dose of tacrolimus was found. Moreover, there were no significant changes in the tacrolimus levels and the daily dose after the combination with micafungin (p>0.05).

CONCLUSIONS

Our results suggest that there is considerable variability in the interaction between tacrolimus and different antifungal drugs. The dose of tacrolimus should be reduced by two-thirds and one-third before the combination with voriconazole and fluconazole, respectively. It is not recommended that the dose should be adjusted before combination with other antifungal drugs, and the dose should be adjusted under the guidance of therapeutic drug monitoring.

Azoles versus conventional amphotericin B for the treatment of candidemia: A meta-analysis of randomized controlled trials

Because exclusive use of echinocandins can induce the drug-resistant strains, appropriate use of azoles and polyenes is still necessary in the treatment of candidemia. In this study, we conducted a meta-analysis of randomized controlled trials regarding the efficacy and safety of azole and polyene antifungals in the treatment of candidemia. MEDLINE and the Cochrane Register of Controlled Trials were used as reference databases, and papers published up to June 10, 2019 were searched. The search results were carefully scrutinized, duplicate references were removed, and the study was ultimately carried out using three reports. Among azole antifungals, fluconazole and voriconazole were extracted, however; only conventional amphotericin B (AMPH-B) was extracted among polyene antifungals. Treatment successes with the use of azoles and AMPH-B were compared, and findings showed that AMPH-B was significantly superior (RR = 0.90, 95% CI 0.82-1.00, p = 0.04). However, there was no significant difference in mortality (RR = 0.87, 95% CI 0.72-1.07, p = 0.19). Analysis of adverse events showed that renal disorders were significantly less common with azoles than with AMPH-B (RR = 0.26, 95% CI 0.10-0.68, p = 0.006). In conclusion, AMPH-B were superior to azoles in terms of efficacy, but had a risk of causing renal disorders.

Current Antimycotics, New Prospects, and Future Approaches to Antifungal Therapy

Fungal infections represent an increasing threat to a growing number of immune- and medically compromised patients. Fungi are eukaryotic organisms and, as such, there is a limited number of selective targets that can be exploited for antifungal drug development. This has also resulted in a very restricted number of antifungal drugs that are clinically available for the treatment of invasive fungal infections at the present time—polyenes, azoles, echinocandins, and flucytosine. Moreover, the utility of available antifungals is limited by toxicity, drug interactions and the emergence of resistance, which contribute to high morbidity and mortality rates. This review will present a brief summary on the landscape of current antifungals and those at different stages of clinical development. We will also briefly touch upon potential new targets and opportunities for novel antifungal strategies to combat the threat of fungal infections.

Anidulafungin Versus Micafungin in the Treatment of Candidemia in Adult Patients

Background

Echinocandins are recommended for the treatment of invasive candidiasis and candidemia. However, there are few studies comparing anidulafungin and micafungin in terms of efficacy and safety. The objective of this study was to evaluate the clinical efficacy and safety between anidulafungin and micafungin treatment for adult patients with candidemia.

Methods

This retrospective cohort study performed on adult candidemia patients diagnosed from January 2006 through December 2018 at a tertiary medical center. The study subjects included adult patients ≥ 19 years with candidemia who were only treated with anidulafungin or micafungin for ≥ 3 days. Clinical characteristics were collected and analyzed. Hepatotoxicity was assessed according to the Common Terminology Criteria for Adverse Events Version 5.0.

Results

A total of 98 patients with candidemia were treated with anidulafungin (n = 52, 53.1%) or micafungin (n = 46, 46.9%). There were no significant differences in age, sex, source of candidemia, and comorbidities between the anidulafungin and micafungin groups. Although there were more patients with abnormal baseline liver function test (LFT) in the anidulafungin group, the rate of clinical response (51.9% vs. 46.7%), mycological response (76.9% vs. 67.4%), and mortality (30-day mortality 26.9% vs. 21.7% and 90-day mortality 78.8% vs. 73.9%) was similar between the anidulafungin and micafungin groups. Also, there was no significant difference in terms of hepatotoxicity, even among the patients with abnormal baseline LFT between the two groups.

Conclusions

Our results suggest that clinical efficacy and safety may be similar between anidulafungin and micafungin treatment for adult patients with candidemia.

Electronic supplementary material

The online version of this article (10.1007/s11046-020-00471-8) contains supplementary material, which is available to authorized users.

Caspofungin: a review of its characteristics, activity, and use in intensive care units

INTRODUCTION

Candidemia is the fourth frequent reason of healthcare-related bloodstream infections in critically ill patients. For initial management of (suspected) invasive candidiasis in critically ill patients, usage of an echinocandin, e.g. caspofungin, has been recommended.

AREAS COVERED

In this study, characteristics of caspofungin and its use in intensive care unit (ICU) patients are reviewed based on an electronic search using PubMed and Google scholar.

EXPERT OPINION

Caspofungin is a semisynthetic derivative from pneumocandin B and the first member of the echinocandins that was approved by the U.S. Food and Drug Administration (FDA) to fight fungal infection. Caspofungin inhibits the enzyme β(1,3)-D-glucan synthase of the fungal cell wall resulted in inhibition of the synthesis of β(1,3)-D-glucan. For critically ill patients, inter- and intraindividual variations affect the caspofungin concentration. The incidence rates and densities of candidemia in surgical ICUs may be higher than medical ICUs resulting in a higher burden of candidemia in surgical ICUs. However, the mortality rate in surgical ICU patients with candidemia is higher than that medical ICU patients due to differences in their underlying conditions.

Caspofungin induces the release of Ca2+ ions from internal stores by activating ryanodine receptor-dependent pathways in human tracheal epithelial cells

The antimycotic drug caspofungin is known to alter the cell function of cardiomyocytes and the cilia-bearing cells of the tracheal epithelium. The objective of this study was to investigate the homeostasis of intracellular Ca²⁺ concentration ([Ca²⁺]_i) after exposure to caspofungin in isolated human tracheal epithelial cells. The [Ca²⁺]_i was measured using the ratiometric fluoroprobe FURA-2 AM. We recorded two groups of epithelial cells with distinct responses to caspofungin exposure, which demonstrated either a rapid transient rise in [Ca²⁺]_i or a sustained elevation of [Ca²⁺]_i. Both patterns of Ca²⁺ kinetics were still observed when an influx of transmembraneous Ca²⁺ ions was pharmacologically inhibited. Furthermore, in extracellular buffer solutions without Ca²⁺ ions, caspofungin exposure still evoked this characteristic rise in [Ca²⁺]_i. To shed light on the origin of the Ca²⁺ ions responsible for the elevation in [Ca²⁺]_i we investigated the possible intracellular storage of Ca²⁺ ions. The depletion of mitochondrial Ca²⁺ stores using 25 µM 2,4-dinitrophenol (DNP) did not prevent the caspofungin-induced rise in [Ca²⁺]_i, which was rapid and transient. However, the application of caffeine (30 mM) to discharge Ca²⁺ ions that were presumably stored in the endoplasmic reticulum (ER) prior to caspofungin exposure completely inhibited the caspofungin-induced changes in [Ca²⁺]_i levels. When the ER-bound IP₃ receptors were blocked by 2-APB (40 µM), we observed a delayed transient rise in [Ca²⁺]_i as a response to the caspofungin. Inhibition of the ryanodine receptors (RyR) using 40 µM ryanodine completely prevented the caspofungin-induced elevation of [Ca²⁺]_i. In summary, caspofungin has been shown to trigger an increase in [Ca²⁺]_i independent from extracellular Ca²⁺ ions by liberating the Ca²⁺ ions stored in the ER, mainly via a RyR pathway.

Effects of methyl oleate and microparticle-enhanced cultivation on echinocandin B fermentation titer

Echinocandin B (ECB) is a key precursor of antifungal agent Anidulafungin, which has demonstrated clinical efficacy in patients with invasive candidiasis. In this study, the effects of microparticle-enhanced cultivation and methyl oleate on echinocandin B fermentation titer were investigated. The results showed that the titer was significantly influenced by the morphological type of mycelium, and mycelium pellet was beneficial to improve the titer of this secondary metabolism. First, different carbon sources were chosen for the fermentation, and methyl oleate achieved the highest echinocandin B titer of 2133 ± 50 mg/L, which was two times higher than that of the mannitol. The study further investigated the metabolic process of the fermentation, and the results showed that L-threonine concentration inside the cell could reach 275 mg/L at 168 h with methyl oleate, about 2.5 times higher than that of the mannitol. Therefore, L-threonine may be a key precursor of echinocandin B. In the end, a new method of adding microparticles for improving the mycelial morphology was used, and the addition of talcum powder (20 g/L, diameter of 45 µm) could make the maximum titer of echinocandin B reach 3148 ± 100 mg/L.

Review on Current Status of Echinocandins Use

Fungal infections are rising all over the world every year. There are only five medical compound classes for treatment: triazoles, echinocandins, polyenes, flucytosine and allylamine. Currently, echinocandins are the most important compounds, because of their wide activity spectrum and much lower sides effects that may occur during therapy with other drugs. Echinocandins are secondary metabolites of fungi, which can inhibit the biosynthesis of β-(1,3)-D-glucan. These compounds have fungicidal and fungistatic activity depending on different genera of fungi, against which they are used. Echinocandin resistance is rare—the major cause of resistance is mutations in the gene encoding the β-(1,3)-D-glucan synthase enzyme. In this review of the literature we have summarized the characteristics of echinocandins, the mechanism of their antifungal activity with pharmacokinetics and pharmacodynamics, and the resistance issue.

Antifungal use in the surgical ICU patient

PURPOSE OF REVIEW

The successful treatment of surgical fungal infections depends of a timely and adequate source control alongside with the use of prompt systemic antifungals. The main challenge of antifungal use in critically ill surgical patients is to find a balance between rational versus indiscriminate use in order to accomplish an antifungal stewardship program.

RECENT FINDINGS

Surgical fungal infections represent an important burden in the daily clinical activity in many ICUs. The efficacy of the available antifungal drugs has not been adequately assessed in randomized controlled trials with surgical fungal infections in ICU patients. Most clinical experience is limited to case reports or uncontrolled case series. Due to the lack of adequate scientific evidence to assess the role of the different antifungals in surgical ICU patients, it is usually suggested to follow the recommendations for invasive candidiasis and candidemia.

SUMMARY

Antifungal use in the surgical patients admitted to an ICU is a complex matter and there are several elements to consider like the presence of septic shock and multiorgan failure, local epidemiology and antifungal resistance, among others. The proper use of antifungals alongside early recognition and prompt source control, are critical factors for improved outcomes.

Herbal ethosomal gel containing luliconazole for productive relevance in the field of biomedicine

This study includes development, characterization, and optimization of herbal ethosomal formulation. The aim of the present study is to develop drug loaded ethosomes capped with Azadirachta indica (neem) which, was further incorporated in Carbopol 934 K thereby, resulting in the formation of ethosomal gel. The formulation is aimed to express effective treatment against fungal infection. The build was formulated using drug (Luliconazole), soyalecithin, ethanolic neem extract and propylene glycol. In total nine ethosomal, formulations of distinct concentrations of ingredients were processed, to determine out the optimized formulation among the all. Further the prepared drug loaded ethosomes were subjected to various evaluation parameters like particle size, zeta potential, polydispersity index (PDI) and % entrapment efficiency. For the evaluation of its surface morphology, transmission electron microscopy was executed whereas, atomic force microscopy was carried out which contributes in detail and depth information of surface morphology. For the analysis of thermal behavior Thermal gravimetric analysis graph was obtained for luliconazole, soyalecithin, neem extract, physical mixture and optimized formulation (LF5). Attenuated total internal reflection Fourier transforms infra-red spectroscopy was performed for luliconazole, soyalecithin, neem extract, physical mixture, and optimized formulation (LF5) to examine the interaction between the drug and the excipients. Viscosity, pH, spreadability and extrudability of the ethosomal gel were calculated to determine the suitability of the formulation for topical application. In vitro drug permeation study and antifungal activity was executed out with the aid of Wistar albino rat skin model and tube dilution assay respectively. The complete study wrap up, that this herbal ethosomal approach provides advanced sustained and targeted delivery of luliconazole. On analyzing the results, ethosomal formulation LF5 was found to be optimized one, due to its optimum concentration of soyalecithin (300 mg) and ethanol (35%). Hence it has maximum entrapment efficiency of 86.56 ± 0.74%. Optimum vesicle size, zeta potential, and PDI were found to be 155.30 ± 1.2 nm, - 42.20 ± 0.3 mV, and 0.186 ± 0.07 respectively. In vitro drug permeation study expresses release of 83.45 ± 2.51 in 24 h whereas; the in vivo activity proved that LF5 is more active and effective against Candida parapsilosis in comparison to Aspergillus niger. In the end, it was estimated that ethosomal suspension and lyophilized ethosomal suspension was utmost stable at 4 °C/60 ± 5 RH. The complete study clearly indicates that the buildup of ethosomal formulation with luliconazole and neem extract show synergistic effect thereby, expressing excellent result against the treatment of fungal infection.

Chromatographic methods for echinocandin antifungal drugs determination in bioanalysis

The increase of fungal resistance to drugs, such as azole family, gave rise to the development of new antifungals. In this context, echinocandins emerged as a promising alternative for antifungal therapies. Following the commercialization of caspofungin in 2001, echinocandins became the first-line therapy for invasive candidiasis in different patient populations. The quantification of these drugs has gained importance since pharmacokinetic/pharmacodynamic and resistance studies are a paramount concern. This fact has led us to exhaustively examine the methodologies used for the analysis of echinocandins in biological fluids, which are mainly based on LC coupled to different detection techniques. In this review, we summarize the analytical methods for the quantification of echinocandins focusing on sample treatment, chromatographic separation and detection methods.

New Paenibacillus strain produces a family of linear and cyclic antimicrobial lipopeptides: cyclization is not essential for their antimicrobial activity

A new bacterial isolate, Paenibacillus sp. OSY-N, showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria. Antimicrobials produced by this strain were purified by reverse-phase high-performance liquid chromatography. Structural analysis, using mass spectrometry, of a single active HPLC fraction revealed two known cyclic lipopeptides (BMY-28160 and permetin A), a new cyclic lipopeptide, and the linear counterparts of these cyclic compounds. The latter were designated as paenipeptins A, B and C, respectively. The paenipeptins have not been reported before as naturally occurring products. Paenipeptins B and C differ at the acyl side chain; paenipeptin C contains a C8-, instead of C7-fatty acyl side chain. To demonstrate unequivocally the antimicrobial activity of the linear forms of this family of cyclic lipopeptides, analogs of the paenipeptins were synthesized chemically and their antimicrobial activity was tested individually. The synthetic linear lipopeptide with an octanoic acid side chain (designated as paenipeptin C΄) showed potent antimicrobial activity with minimum inhibitory concentrations of 0.5-4.0 μg/mL for Gram-negative and 0.5-32 μg/mL for Gram-positive bacteria. Findings demonstrated that peptide cyclization in this lipopeptide family is not essential for their antimicrobial activity. Most importantly, linear lipopeptides are more accessible than their cyclic counterparts through chemical synthesis.

Recent advances in delivery of antifungal agents for therapeutic management of candidiasis

Candidiasis is a fungal infection caused by yeasts that belong to the genus Candida. There are over twenty species of Candida yeasts that can cause infection in humans, the most common of which is Candida albicans. Candida yeasts normally reside in the intestinal tract and can be found on mucous membranes and skin without causing infection; however, overgrowth of these organisms can cause symptoms to develop. Presence of other diseases that compromises the patient's immunity makes it more difficult to treat. Candidiasis is majorly divided into superficial infections (oral or vaginal) and systemic infections, also known as invasive candidiasis. The conventional therapeutic modalities used to treat candidiasis are associated with several side effects that limits the dose and dosing frequency. Development of novel drug delivery systems for reduction in dose and alleviation of side effects is an important strategy to improve the clinical efficacy and patient acceptability. This review gives a bird's eye view of the classification and current therapeutic regime of candidiasis. It presents the varied types of drug delivery systems that have been exploited for delivery of antifungal agents with measurable benefits. It also touches upon echinocandins a relatively new class of drugs that are amenable for translation into novel dosage forms with application against biofilm producing and fluconazole resistant strains contributing to a better therapeutic management of candidiasis.

Effects of Echinocandins in Combination with Nikkomycin Z against Invasive Candida albicans Bloodstream Isolates and the fks Mutants

We evaluated the in vitro and in vivo effects of nikkomycin Z combined with an echinocandin (anidulafungin or micafungin) against two Candida albicans isolates and their lab-derived echinocandin-resistant fks mutants with FKS1 S645Y and FKS1 S645P. Synergistic effects were observed in all tested strains (fractional inhibitory concentration index, <0.5). Enhanced survival was observed in an immunocompromised murine model (log-rank test, P < 0.02). Our study demonstrated the therapeutic potential of nikkomycin Z-echinocandin combinations in managing echinocandin resistance.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

A Review of Antiviral and Antifungal Use and Safety during Pregnancy

Antiviral and antifungal use in pregnancy presents challenges because of the paucity of clinical and safety data for many agents in these classes. If untreated, viral and fungal infections can have deleterious effects on both maternal and fetal health. Understanding the use and risks of these medications in pregnancy is vital to provide appropriate care. This article reviews the current literature for the use of antiviral and antifungals, the pharmacokinetics of these agents, and their safety in pregnancy.

Micafungin versus caspofungin in the treatment of Candida glabrata infection: a case report

Background

Micafungin and caspofungin, which are both echinocandins, elicit their antifungal effects by suppressing the synthesis of β-D-glucan, an essential component of fungal cell walls. If micafungin is not effective against a fungal infection, is it unreasonable to switch to caspofungin?

Case presentation

An 80-year-old Asian man presented to our hospital with brain and lung abscesses. Klebsiella pneumonia and Escherichia coli were identified by sputa culture and Streptococcus mitis was identified in the brain abscess culture obtained by drainage surgery. He was treated with antibiotics and both abscesses shrank after the treatment. But he continued to have a high fever and Candida glabrata was identified by blood culture. The origin of the infection was not clarified and micafungin was administered intravenously. The fungus showed poor susceptibility to micafungin; we then switched the antifungal from micafungin to caspofungin. After caspofungin treatment, his body temperature remained below 37 °C and his β-D-glucan levels decreased remarkably.

Conclusions

In vitro, micafungin is considered more effective against C. glabrata because its minimum inhibitory concentration against C. glabrata is lower than that of caspofungin. However, in vivo, there is no significantly different effect between the two drugs. When micafungin is not effective against candidiasis, a switch to caspofungin might be applicable because the pharmacokinetics in each echinocandin is slightly different.

Micafungin versus anidulafungin in critically ill patients with invasive candidiasis: a retrospective study

Background

In critically ill patients the incidence of invasive fungal infections caused by Candida spp. has increased remarkably. Echinocandins are recommended as initial treatment for invasive fungal infections. The safety and efficacy of micafungin compared to caspofungin is similar, but no comparison is made between anidulafungin and micafungin concerning safety and efficacy. We therefore performed a retrospective study to assess these aspects in critically ill patients with invasive candidiasis.

Methods

All patients in the intensive care unit (ICU) with invasive candidiasis, who were only treated with anidulafungin or micafungin, between January 2012 and December 2014 were retrospectively included. Baseline demographic characteristics, infection characteristics and patient courses were assessed.

Results

A total of 63 patients received either anidulafungin (n = 30) or micafungin (n = 33) at the discretion of the attending intensivist. Baseline characteristics were comparable between the two groups, suggesting similar risk for developing invasive candidiasis. Patients with invasive candidiasis and liver failure were more often treated with anidulafungin than micafungin. Response rates were similar for both groups. No difference was observed in 28-day mortality, but 90-day mortality was higher in patients on anidulafungin. Multivariable cox regression analysis showed that age and serum bilirubin were the best parameters for the prediction of 90-day mortality, whereas APACHE II, Candida score and antifungal therapy did not contribute (P > 0.05). None of the patients developed impaired liver function related to antifungal use and no differences were seen in prothrombin time, serum transaminases and bilirubin levels between the groups, after exclusion of patients with liver injury or failure.

Conclusion

Micafungin can be safely and effectively used in critically ill patients with invasive candidiasis. The observed increased 90-day mortality with anidulafungin can be explained by intensivists unnecessarily avoiding micafungin in patients with liver injury and failure.

Outcome of Candida Parapsilosis Complex Infections Treated with Caspofungin in Children

BACKGROUND

We aimed to evaluate the correlation of caspofungin E-tests with the prognosis and response to caspofungin therapy of Candida parapsilosis complex bloodstream infections in children hospitalized in a pediatric intensive care unit.

METHODS

All children who had C. parapsilosis complex bloodstream infections and who were treated with caspofungin were included in this retrospective study. For each patient, the following parameters, including all consecutive blood and central venous catheter (CVC) cultures, the duration between diagnosis and CVC removal, mortality rate, relapses of the C. parapsilosis complex infections as well as the demographic features, were recorded.

RESULTS

The central venous catheter survival rate was 33.3% under caspofungin treatment. In 92.4 % of the patients, the negative culture was achieved within a median duration of 12.5 days. The rate of relapses was 18.9%. The overall mortality rate was 37.7% (20 of 53 patients), and the 30-days mortality rate was 7.5% (4 of 53 patients). There was no statistically significant difference between the groups with MIC<2 mg/l and MIC =2 mg/l using CVC survival rate; rate and duration of achieving negative blood culture for C. parapsilosis complex; duration of hospital stay; rate and duration of relapses; overall mortality and 30-days mortality.

CONCLUSIONS

The beneficial effects of Caspofungin on biofilms has been shown in vivo, while its impact in children for maintenance of CVC was limited in our study but should not be underestimated in children who strongly need the presence of CVCs. The clinicians should weigh their priority for their patients and choose the optimal antifungal therapy for C. parapsilosis complex infections in children.

Echinocandins: The Expanding Antifungal Armamentarium

The echinocandins are large lipopeptide molecules that, since their discovery approximately 41 years ago, have emerged as important additions to the expanding armamentarium against invasive fungal diseases. Echinocandins exert in vitro and in vivo fungicidal action against most Candida species and fungistatic action against Aspergillus species. However, the population of patients at risk for developing invasive fungal infections continues to increase. New therapeutic strategies using echinocandins are needed to improve clinical outcomes in patients with invasive fungal disease.

Antifungal peptides: To be or not to be membrane active

Most antifungal peptides (AFPs), if not all, have membrane activity, while some also have alternative targets. Fungal membranes share many characteristics with mammalian membranes with only a few differences, such as differences in sphingolipids, phosphatidylinositol (PI) content and the main sterol is ergosterol. Fungal membranes are also more negative and a better target for cationic AFPs. Targeting just the fungal membrane lipids such as phosphatidylinositol and/or ergosterol by AFPs often translates into mammalian cell toxicity. Conversely, a specific AFP target in the fungal pathogen, such as glucosylceramide, mannosyldiinositol phosphorylceramide or a fungal protein target translates into high pathogen selectivity. However, a lower target concentration, absence or change in the specific fungal target can naturally lead to resistance, although such resistance in turn could result in reduced pathogen virulence. The question is then to be or not to be membrane active - what is the best choice for a successful AFP? In this review we deliberate on this question by focusing on the recent advances in our knowledge on how natural AFPs target fungi.

In vitro interactions between anidulafungin and nonsteroidal anti-inflammatory drugs on biofilms of Candida spp

Candida spp. are responsible for many biomaterial-related infections; they give rise to infective pathologies typically associated with biofilm formation. We recently reported that the echinocandin anidulafungin (ANF) showed a strong in vitro activity against both planktonic and biofilms cells. Herein, we report the antifungal activities of ANF alone and in association with some non-steroidal anti-inflammatory drugs (NSAIDs) against nine Candida strain biofilms: four Candida albicans, two Candida glabrata and three Candida guilliermondii. The activity of ANF was assessed using an in vitro microbiological model relevant for clinical practice. ANF proved oneself to be active against biofilms cells, and a clear-cut synergism was found against Candida species biofilms when ANF was used in combination with three NSAIDs: aspirin, diclofenac, ibuprofen. The positive synergism against Candida spp. of ANF in association with aspirin or the other NSAIDs proved to be a very effective antifungal treatment (FICI<0.5). These results may provide the starting point for new combination therapies of ANF with NSAIDs against Candida biofilm pathologies.

Albumin Enhances Caspofungin Activity against Aspergillus Species by Facilitating Drug Delivery to Germinating Hyphae

The modest in vitro activity of echinocandins against Aspergillus implies that host-related factors augment the action of these antifungal agents in vivo. We found that, in contrast to the other antifungal agents (voriconazole, amphotericin B) tested, caspofungin exhibited a profound increase in activity against various Aspergillus species under conditions of cell culture growth, as evidenced by a ≥4-fold decrease in minimum effective concentrations (MECs) (P = 0. 0005). Importantly, the enhanced activity of caspofungin against Aspergillus spp. under cell culture conditions was strictly dependent on serum albumin and was not observed with the other two echinocandins, micafungin and anidulafungin. Of interest, fluorescently labeled albumin bound preferentially on the surface of germinating Aspergillus hyphae, and this interaction was further enhanced upon treatment with caspofungin. In addition, supplementation of cell culture medium with albumin resulted in a significant, 5-fold increase in association of fluorescently labeled caspofungin with Aspergillus hyphae (P < 0.0001). Collectively, we found a novel synergistic interaction between albumin and caspofungin, with albumin acting as a potential carrier molecule to facilitate antifungal drug delivery to Aspergillus hyphae.

Identification of New Antifungal Compounds Targeting Thioredoxin Reductase of Paracoccidioides Genus

The prevalence of invasive fungal infections worldwide has increased in the last decades. The development of specific drugs targeting pathogenic fungi without producing collateral damage to mammalian cells is a daunting pharmacological challenge. Indeed, many of the toxicities and drug interactions observed with contemporary antifungal therapies can be attributed to “nonselective” interactions with enzymes or cell membrane systems found in mammalian host cells. A computer-aided screening strategy against the TRR1 protein of Paracoccidioides lutzii is presented here. Initially, a bank of commercially available compounds from Life Chemicals provider was docked to model by virtual screening simulations. The small molecules that interact with the model were ranked and, among the best hits, twelve compounds out of 3,000 commercially-available candidates were selected. These molecules were synthesized for validation and in vitro antifungal activity assays for Paracoccidioides lutzii and P. brasiliensis were performed. From 12 molecules tested, 3 harbor inhibitory activity in antifungal assays against the two pathogenic fungi. Corroborating these findings, the molecules have inhibitory activity against the purified recombinant enzyme TRR1 in biochemical assays. Therefore, a rational combination of molecular modeling simulations and virtual screening of new drugs has provided a cost-effective solution to an early-stage medicinal challenge. These results provide a promising technique to the development of new and innovative drugs.

Network Modeling Reveals Cross Talk of MAP Kinases during Adaptation to Caspofungin Stress in Aspergillus fumigatus

Mitogen activated protein kinases (MAPKs) are highly conserved in eukaryotic organisms. In pathogenic fungi, their activities were assigned to different physiological functions including drug adaptation and resistance. Aspergillus fumigatus is a human pathogenic fungus, which causes life-threatening invasive infections. Therapeutic options against invasive mycoses are still limited. One of the clinically used drugs is caspofungin, which specifically targets the fungal cell wall biosynthesis. A systems biology approach, based on comprehensive transcriptome data sets and mathematical modeling, was employed to infer a regulatory network and identify key interactions during adaptation to caspofungin stress in A. fumigatus. Mathematical modeling and experimental validations confirmed an intimate cross talk occurring between the cell wall-integrity and the high osmolarity-glycerol signaling pathways. Specifically, increased concentrations of caspofungin promoted activation of these signalings. Moreover, caspofungin affected the intracellular transport, which caused an additional osmotic stress that is independent of glucan inhibition. High concentrations of caspofungin reduced this osmotic stress, and thus decreased its toxic activity. Our results demonstrated that MAPK signaling pathways play a key role during caspofungin adaptation and are contributing to the paradoxical effect exerted by this drug.

Consensus guidelines for optimising antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy, 2014

Antifungal agents may be associated with significant toxicity or drug interactions leading to sub-therapeutic antifungal drug concentrations and poorer clinical outcomes for patients with haematological malignancy. These risks may be minimised by clinical assessment, laboratory monitoring, avoidance of particular drug combinations and dose modification. Specific measures, such as the optimal timing of oral drug administration in relation to meals, use of pre-hydration and electrolyte supplementation may also be required. Therapeutic drug monitoring (TDM) of antifungal agents is warranted, especially where non-compliance, non-linear pharmacokinetics, inadequate absorption, a narrow therapeutic window, suspected drug interaction or unexpected toxicity are encountered. Recommended indications for voriconazole and posaconazole TDM in the clinical management of haematology patients are provided. With emerging knowledge regarding the impact of pharmacogenomics upon metabolism of azole agents (particularly voriconazole), potential applications of pharmacogenomic evaluation to clinical practice are proposed.

Influence of echinocandin administration on hemodynamic parameters in medical intensive care unit patients: a single center prospective study

PURPOSE

Fungal infections present a constant risk to critically ill and immunocompromised patients. Therefore, treatment guidelines recommend echinocandins as first-line antifungals in critically ill patients to improve patient outcomes. Echinocandins are usually well tolerated; nevertheless, rare adverse events can occur. There are reports of temporary deterioration of hemodynamic parameters during loading doses, especially in critically ill patients. The objective of this study is to analyze the hemodynamic changes during administration of the echinocandin antifungals, caspofungin and anidulafungin, in medical intensive care unit patients.

METHODS

A prospective study in medical ICU patients receiving echinocandins was monitored using single-indicator transpulmonary thermodilution (TPTD). TPTD measurements were performed immediately before, directly after, and 4 h after echinocandins on two following days.

RESULTS

Mean arterial pressure and also diastolic blood pressure showed significant changes (p < 0.042 and p < 0.007) after echinocandin application in the measurement immediately after application, but not after 4 h. Basic hemodynamic parameters as well as the TPTD-derived cardiac function parameters did not significantly change after echinocandin application at all. In patients with the need for norepinephrine therapy, the vasopressor dose was not statistically significantly altered.

CONCLUSION

To conclude, administration of echinocandins in this observed study population is safe, even in severely critically ill patients if application rules of these agents are followed. However, adverse effects could be observed and practitioners should be cognizant of these effects. These observations can be optimized by high-level assessments, such as the pulse contour cardiac output monitoring, and clinicians should continue to be vigilant with cardiac monitoring of patients receiving echinocandin antifungals.

Echinocandin use in hospitalized patients: a multi-institutional study

BACKGROUND

The echinocandin antifungals are recommended as initial therapy in hospitalized patients with candidemia. Contemporary usage rates and indication for use of echinocandins have not been studied in the United States. The purpose of this study was to evaluate echinocandin usage patterns in community and academic teaching hospitals over time and to evaluate dose, duration of therapy and indications for use.

METHODS

This study used hospital pharmacy databases from academic and community hospitals to collect information on adult inpatients given systemic antifungal agents from 2008 to 2012. Patient medical information was also obtained from randomly selected patients given an echinocandin over the same time period.

RESULTS

Echinocandin use was determined for 4 academic and 34 community hospitals. A significant increase in echinocandin use was observed in academic and community hospitals during the time period (P < 0.001). Two hundred forty-two randomly selected patients receiving an echinocandin were retrospectively reviewed. Indications for echinocandin use did not change during the time period and included empiric therapy in a high-risk patient without subsequent mycologic confirmation from a normally sterile site (55%), systemic candidiasis (43%) and prophylactic (2%). Fifty-six percent of patients had at least 1 anatomic site of mycologic growth; most commonly urine only (14%), respiratory only (12%) or blood only (7%). In patients with candidemia, the hospital treatment course with an echinocandin averaged 8.4 ± 7.9 days (range, 1-35 days).

CONCLUSIONS

This study provides useful benchmark data on antifungal use and indications for use that could be used for antifungal stewardship program comparisons.