Antifungal combination therapy: clinical potential

Synergistic Antifungal Effect and In Vivo Toxicity of a Monoterpene Isoespintanol Obtained from Oxandra xylopioides Diels

Candida sp. infections are a threat to global health, with high morbidity and mortality rates due to drug resistance, especially in immunocompromised people. For this reason, the search for new alternatives is urgent, and in recent years, a combined therapy with natural compounds has been proposed. Considering the biological potential of isoespintanol (ISO) and continuing its study, the objective of this research was to assess the effect of ISO in combination with the antifungals fluconazole (FLZ), amphotericin B (AFB) and caspofungin (CASP) against clinical isolates of C. tropicalis and to evaluate the cytotoxic effect of this compound in the acute phase (days 0 and 14) and chronic phase (days 0, 14, 28, 42, 56, 70 and 84) in female mice (Mus musculus) of the Balb/c lineage. The results show that ISO can potentiate the effect of FLZ, AFB and CASP, showing synergism with these antifungals. An evaluation of the mice via direct observation showed no behavioral changes or variations in weight during treatment; furthermore, an analysis of the cytokines IFN-γ and TNF in plasma, peritoneal cavity lavage (PCL) and bronchoalveolar lavage (BAL) indicated that there was no inflammation process. In addition, histopathological studies of the lungs, liver and kidneys showed no signs of toxicity caused by ISO. This was consistent with an analysis of oxaloacetic transaminases (GOT) and pyruvic transaminases (GPT), which remained in the standard range. These findings indicate that ISO does not have a cytotoxic effect at the doses evaluated, placing it as a monoterpene of interest in the search for compounds with pharmacological potential.

Evaluation of antifungal and apoptotic effects of linalool, citral, and carvacrol separately and in combination with nystatin against clinical isolates of Pichia kudriavzevii

Pichia kudriavzevii (formerly Candida krusei) poses a significant threat to immunocompromised patients due to its inherent resistance to various antifungal drugs. This study explored the anticandidal potential of citral, linalool, and carvacrol in combination with nystatin against P. kudriavzevii strains.Using the microdilution method following CLSI guidelines, Minimum Inhibitory Concentrations (MICs) and fungicidal concentrations (MFCs) were determined. Citral exhibited MIC values ranging from 50 to 100 µg/ml, averaging 70.24 ± 16.99 µg/ml, while carvacrol had MIC values of 50 to 100 µg/ml, averaging 86.90 ± 16.99 µg/ml. Linalool demonstrated weaker antifungal activity, with MIC values between 100 and 200 µg/ml, averaging 150 ± 38.73 µg/ml. The study assessed the synergistic effectsof these phenols with nystatin through fractional inhibitory concentration indices (FICIS). In addition, flow cytometry was employed to assess apoptosis induction in P. kudriavzevii cells.Carvacrol displayed a remarkable synergistic effect in combination with nystatin against all 21 isolates tested. Conversely, linalool showed synergy in 17 isolates, while citral exhibited synergy in only 2 isolates. These findings highlight distinct patterns of synergy between the different compounds and nystatin against P. kudriavzevii. Also, Carvacrol emerged as the most potent inducer of apoptosis across all P. kudriavzevii strains, followed by citral and linalool. This suggests that carvacrol not only possesses a stronger antifungal effect but also has a more pronounced ability to trigger programmed cell death in P. kudriavzevii. In conclusion, the study supports the potential of carvacrol, citral and linalool, as anticandidal agents, suggesting their supplementation with nystatin for treating P. kudriavzevii infections.

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.

Simultaneous Quantification of Seven Antifungal Agents in Human Serum Using Liquid Chromatography-Tandem Mass Spectrometry

Systemic antifungal agents are essential for high-risk patients undergoing immunosuppressive therapy or cancer chemotherapy because of the rapid increase in opportunistic fungal infections. Therapeutic drug monitoring is crucial to ensuring the efficacy and safety of antifungal agents owing to their pharmacokinetic variability. In the present study, we developed and validated a quantitative method for the simultaneous detection of seven commonly used antifungal drugs (amphotericin B, isavuconazole, voriconazole, fluconazole, posaconazole, caspofungin, and micafungin) using liquid chromatography-tandem mass spectrometry. Methanol (containing 0.1% formic acid) was used for protein precipitation and only 50 μL of serum was required for the analysis. Chromatographic separation was conducted using a Waters Acquity UPLC C8 column, and one stable isotope-labeled agent and two analogs were used as internal standards. The calibration curves ranged from 0.1 to 50 μg/mL for all agents, and the correlation coefficient (R2) for all calibration curves was above 0.9835. The intra-day precision (1.2-11.2%), inter-day precision (2.4-13.2%), and mean bias values (-10.9 to 13.6%) were within an acceptable range of ±15%. Successful implementation of the developed method in clinical practice would facilitate the effective monitoring of these antifungal agents.

Clorgyline Analogs Synergize with Azoles against Drug Efflux in Candida auris

Concern about the global emergence of multidrug-resistant fungal pathogens led us to explore the use of combination therapy to combat azole resistance in Candida auris. Clorgyline had previously been shown to be a multi-target inhibitor of Cdr1 and Mdr1 efflux pumps of Candida albicans and Candida glabrata. A screen for antifungal sensitizers among synthetic analogs of Clorgyline detected interactions with the C. auris efflux pump azole substrates Posaconazole and Voriconazole. Of six Clorgyline analogs, M19 and M25 were identified as potential sensitizers of azole resistance. M19 and M25 were found to act synergistically with azoles against resistant C. auris clade I isolates and recombinant Saccharomyces cerevisiae strains overexpressing C. auris efflux pumps. Nile Red assays with the recombinant strains showed M19 and M25 inhibited the activity of Cdr1 and Mdr1 efflux pumps that are known to play key roles in azole resistance in C. auris clades I, III, and IV. While Clorgyline, M19 and M25 uncoupled the Oligomycin-sensitive ATPase activity of Cdr1 from C. albicans and C. auris, their mode of action is yet to be fully elucidated. The experimental combinations described herein provides a starting point to combat azole resistance dominated by overexpression of CauCdr1 in C. auris clades I and IV and CauMdr1 in C. auris clade III.

Tamarindus indica Extract as a Promising Antimicrobial and Antivirulence Therapy

The worldwide crises from multi-drug-resistant (MDR) bacterial infections are pushing us to search for new alternative therapies. The renewed interest in medicinal plants has gained the attention of our research group. Tamarindus indica L. (T. indica) is one of the traditional medicines used for a wide range of diseases. Therefore, we evaluated the antimicrobial activities of ethanolic extract of T. indica. The inhibitions zones, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and fractional inhibitor concentration indices (FICI) against Gram+ve and −ve pathogens were detected. The bioactive compounds from T. indica extract were identified by mass spectroscopy, thin-layer chromatography, and bio-autographic assay. We performed scanning electron microscopy (SEM) and molecular docking studies to confirm possible mechanisms of actions and antivirulence activities, respectively. We found more promising antimicrobial activities against MDR pathogens with MIC and MBC values for Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), i.e., (0.78, 3.12 mg/mL) and (1.56, 3.12 mg/mL), respectively. The antimicrobial activities of this extract were attributed to its capability to impair cell membrane permeability, inducing bacterial cell lysis, which was confirmed by the morphological changes observed under SEM. The synergistic interactions between this extract and commonly used antibiotics were confirmed (FICI values < 0.5). The bioactive compounds of this extract were bis (2-ethylhexyl)phthalate, phenol, 2,4-bis(1,1-dimethylethyl), 1,2-benzenedicarboxylic acid, and bis(8-methylnonyl) ester. Additionally, this extract showed antivirulence activities, especially against the S. aureus protease and P. aeruginosa elastase. In conclusion, we hope that pharmaceutical companies can utilize our findings to produce a new formulation of T. indica ethanolic extract with other antibiotics.

Paracoccidioidomycosis: Current Status and Future Trends

Paracoccidioidomycosis (PCM), initially reported in 1908 in the city of São Paulo, Brazil, by Adolpho Lutz, is primarily a systemic and neglected tropical mycosis that may affect individuals with certain risk factors around Latin America, especially Brazil. Paracoccidioides brasiliensis sensu stricto, a classical thermodimorphic fungus associated with PCM, was long considered to represent a monotypic taxon. However, advances in molecular taxonomy revealed several cryptic species, including Paracoccidioides americana, P. restrepiensis, P. venezuelensis, and P. lutzii, that show a preference for skin and mucous membranes, lymph nodes, and respiratory organs but can also affect many other organs. The classical diagnosis of PCM benefits from direct microscopy culture-based, biochemical, and immunological assays in a general microbiology laboratory practice providing a generic identification of the agents. However, molecular assays should be employed to identify Paracoccidioides isolates to the species level, data that would be complemented by epidemiological investigations. From a clinical perspective, all probable and confirmed cases should be treated. The choice of treatment and its duration must be considered, along with the affected organs, process severity, history of previous treatment failure, possibility of administering oral medication, associated diseases, pregnancy, and patient compliance with the proposed treatment regimen. Nevertheless, even after appropriate treatment, there may be relapses, which generally occur 5 years after the apparent cure following treatment, and also, the mycosis may be confused with other diseases. This review provides a comprehensive and critical overview of the immunopathology, laboratory diagnosis, clinical aspects, and current treatment of PCM, highlighting current issues in the identification, treatment, and patient follow-up in light of recent Paracoccidioides species taxonomic developments.

Fungicidal activity of human antimicrobial peptides and their synergistic interaction with common antifungals against multidrug-resistant Candida auris

Emergence of Candida auris, a multidrug-resistant yeast, demonstrates the urgent need for novel antifungal agents. Human antimicrobial peptides (AMPs) are naturally occurring molecules with wide spectrum antimicrobial activity, particularly against a variety of fungi. Therefore, this study examined the antifungal activity of seven different human AMPs against C. auris following the CLSI guidelines. The antifungal activity was further assessed using time kill curve and cell viability assays. For combination interaction, effectiveness of these peptides with three antifungals, fluconazole, amphotericin B, and caspofungin was done following standard protocols. To elucidate the antifungal mechanism, the effects of peptides on membrane permeability were investigated using propidium iodide staining method and confocal imaging. Antifungal susceptibility results showed that all the examined peptides possessed fungicidal effect against C. auris at different levels, with human β-defensin-3 being the most potent antifungal with MIC values ranging from 3.125 to 12.5 µg/ml. Time kill curves further confirmed the killing effect of all the tested peptides. Viability assay showed a significant decrease in the percentage of viable cells exposed to different inhibitory and fungicidal concentrations of each peptide (p < 0.01). Furthermore, peptides showed mostly synergistic interaction when combined with conventional antifungal drugs, with caspofungin showing 100% synergy when combined with different AMPs. As antifungal mechanism, peptides disrupted the membrane permeability at concentrations that correlated with the inhibition of growth. Overall, the findings of this study point towards the application of the tested peptides as a monotherapy or as a combination therapy with antifungal drugs to treat multidrug-resistant C. auris infections.

Mucormycosis an added burden to Covid-19 Patients: An in-depth systematic review

As of 25th July, 2022, global Disease burden of 575,430,244 confirmed cases and over 6,403,511 deaths have been attributed to coronavirus disease 2019 (COVID-19). Co-infections/secondary infections continue to plague patients around the world as result of the co-morbidities like diabetes mellitus, biochemical changes caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) especially significant elevation in free iron levels, immune suppression caused by SARS-CoV-2, and indiscriminate use of systemic corticosteroids for the treatment of severe COVID-19 disease. In such circumstances, opportunistic fungal infections pose significant challenge for COVID-19 disease therapy in patients with other co-morbidities. Although COVID-19-associated Mucormycosis (CAM) has been widely recognized, currently extensive research is being conducted on mucormycosis. It has been widely agreed that patients undergoing corticosteroid therapy are highly susceptible for CAM, henceforth high index of screening and intensive care and management is need of an hour in order to have favorable outcomes in these patients. Diagnosis in such cases is often delayed and eventually the disease progresses quickly which poses added burden to clinician and increases patient load in critical care units of hospitals. A vast perusal of literature indicated that patients with diabetes mellitus and those with other co-morbidities might be highly vulnerable to develop mucormycosis. In the present work, the case series of three patients presented at Chest Disease Hospital Srinagar, Jammu and Kashmir infected with CAM has been described with their epidemiological data in supplementary section. All these cases were found to be affected with co-morbidity of Diabetes Mellitus (DM) and were under corticosteroid therapy. Furthermore, given the significant death rate linked with mucormycosis and the growing understanding of the diseases significance, systematic review of the literature on CAM has been discussed and we have attempted to discuss emerging CAM and related aspects of the disease.

Evaluation for Metastatic Candida Focus and Mortality at Candida-associated Catheter-related Bloodstream Infections at the Pediatric Hematology-oncology Patients

BACKGROUND

Candidemia and Candida-associated catheter-related bloodstream infections (CRBSIs) are the significant cause of mortality and morbidity in patients with malignancy.

METHODS

A retrospective analysis including all pediatric hematologic/oncologic malignancies patients with CRBSIs treated in Dr. Behçet Uz Children Diseases and Surgery Training and Research Hospital between the period of 2009 and 2020.

RESULTS

During the study period, 53 children with CRBSIs associated with Candida species were included. The most common malignancy was acute lymphoblastic leukemia (45.3%) and acute myeloid leukemia (15.1%). A total of 56 Candida isolates were present including non-albicans Candida species (80.4%) and Candida albicans (19.6%). The most common isolated Candida species was Candida parapsilosis (42.9%) and followed by C. albicans (19.6%). The ratio of azole prophylaxis was significantly higher in patients with the non-albicans Candida group (P=0.031). Candida-related endocarditis (vegetation) was present in 2 (3.8%) patients, and the overall rate of hepatosplenic candidiasis was 3.8%. Seven days Candida attributable mortality was 7.5% (4 patients) and 30 days Candida attributable mortality was 11.3% (6 patients). The Candida species responsible for the Candida-related deaths were as following: Candida tropicalis (n=3), C. parapsilosis (n=2), and C. lusitanae (n=1).

CONCLUSION

In pediatric cancer patients with Candida-associated CRBSIs, evaluation of the patient for organ involvement including liver and spleen ultrasonography and cardiac involvement with echocardiography are essential regardless of the patients' clinical picture.

Isavuconazole and Liposomal Amphotericin B as Successful Combination Therapy of Refractory Invasive Candidiasis in a Liver Transplant Recipient: A Case Report and Literature Review

Invasive fungal infections in liver transplant recipients are associated with elevated morbidity and mortality and pose a challenge to the treating physicians. Despite of lacking clinical data, the use of antifungal combination therapy is often considered to improve response rates in an immunocompromised patient population. We herein report a case of refractory invasive candidiasis in a liver transplant recipient treated successfully with a combination of isavuconazole und high-dose liposomal amphotericin B. The antimycotic combination treatment was able to clear a bloodstream infection with C. glabrata and led to regression of bilomas among tolerable side effects. The use of the above-mentioned antifungal combination therapy in a liver transplant recipient has not been reported previously. This case highlights the efficacy and safety of antifungal combination therapy in immunocompromised patients with refractory invasive candidiasis.

In vitro and in vivo analysis of monotherapy and dual therapy with ethyl caffeate and fluconazole on virulence factors of Candida albicans and systemic candidiasis

OBJECTIVES

Candida albicans is the most clinically prevalent cause of systemic fungal infections in the immunocompromised population. The biofilm-forming ability of C. albicans confers resistance to conventional antifungal agents. The main aim of this study was to investigate the antifungal effects of ethyl caffeate (EC) alone and in combination with fluconazole (FLU) against C. albicans isolates.

METHODS

The single and combined antifungal activities of EC and FLU were evaluated against planktonic and biofilm cells of C. albicans by the checkerboard assay, time-kill test, crystal violet assay, live/dead staining, rhodamine 6G (R6G) efflux analysis and hydrolase activity. Monotherapy and dual therapy of EC and FLU against systemic candidiasis in a mouse model was also evaluated.

RESULTS

The results showed that EC+FLU displayed synergism in 14/26 planktonic C. albicans isolates and 11/26 C. albicans biofilms with fractional inhibitory concentration index (FICI) values ranging between 0.06-0.49 and 0.02-0.38, respectively. Compared with monotherapy, the combination of EC+FLU can markedly inhibit adhesion, yeast-to-hyphae transition, premature and mature biofilm metabolism, hydrolase secretion and drug efflux function of C. albicans Z1407 and Z4935. Moreover, EC can potentiate the antifungal activity of FLU to improve mouse survival, reduce fungal burden and alleviate pathological damage in both C. albicans isolates compared with EC or FLU used alone.

CONCLUSION

EC exhibits a moderate antifungal potential but can be a strong synergist with FLU against C. albicans, highlighting the potential of EC in clinical antifungal therapy as a sensitiser.

Drug repurposing strategies in the development of potential antifungal agents

Abstract

The morbidity and mortality caused by invasive fungal infections are increasing across the globe due to developments in transplant surgery, the use of immunosuppressive agents, and the emergence of drug-resistant fungal strains, which has led to a challenge in terms of treatment due to the limitations of three classes of drugs. Hence, it is imperative to establish effective strategies to identify and design new antifungal drugs. Drug repurposing is a potential way of expanding the application of existing drugs. Recently, various existing drugs have been shown to be useful in the prevention and treatment of invasive fungi. In this review, we summarize the currently used antifungal agents. In addition, the most up-to-date information on the effectiveness of existing drugs with antifungal activity is discussed. Moreover, the antifungal mechanisms of existing drugs are highlighted. These data will provide valuable knowledge to stimulate further investigation and clinical application in this field.

Key points

• Conventional antifungal agents have limitations due to the occurrence of drug-resistant strains.

• Non-antifungal drugs act as antifungal agents in various ways toward different targets.

• Non-antifungal drugs with antifungal activity are demonstrated as effective antifungal strategies.

Ellagic Acid Inhibits Trichophyton rubrum Growth via Affecting Ergosterol Biosynthesis and Apoptotic Induction

Background

Trichophyton rubrum, among other dermatophytes, is a major causative agent for superficial dermatomycoses like onychomycosis and tinea pedis, especially among pediatric and geriatric populations. Ellagic acid (EA) and shikonin (SK) have been reported to have many bioactivities, including antifungal activity. However, the mechanism of EA and SK on Trichophyton rubrum has not yet been reported.

Objectives

The purposes of this study were to evaluate the antifungal activities of EA and SK against Trichophyton rubrum and to illuminate the underlying action mechanisms.

Methods

The effect of EA (64, 128, and 256 μg/mL) and SK (8, 4, and 2 μg/mL) on Trichophyton rubrum was investigated with different doses via detecting cell viability, ultrastructure with using a scanning electron microscope (SEM), cell apoptosis and necrosis by using the flow cytometry instrument technique (FCIT), and the ergosterol biosynthesis pathway-related fungal cell membrane key gene expressions in vitro.

Results

SEM detection revealed that the T. rubrum cell surface was shrivelled, folded, and showed deformation and expansion, visible surface peeling, and broken hyphae, and cell contents overflowed after being treated with EA and SK; the cell apoptosis rate was significantly increased in dose-dependent manner after T. rubrum was treated with EA and SK; the qPCR results showed that mRNA expression of MEP4 and SUB1 was downregulated in EA- and SK-treated groups.

Conclusions

Overall, our results revealed the underlying antifungal mechanism of EA and SK, which may be related to the destruction of the fungal cell membrane and inhibition of C14 demethylase and the catalytic rate of squalene cyclooxidase in the ergosterol biosynthesis pathway via downregulation of MEP4 and SUB1, suggesting that EA and SK have the potential to be developed further as a natural antifungal agent for clinical use.

Endocarditis infecciosa debida a candida lusitaniae en un lactante menor: Reporte de caso

Introducción: La endocarditis fúngica es una enfermedad infecciosa agresiva e infrecuente, considerada una emergencia en los servicios hospitalarios. Se ha evidenciado una incidencia de 0-12% del total de las admisiones pediátricas por endocarditis infecciosa. La mortalidad por Candida spp se encuentra alrededor del 50-80% en todos los casos. La Candida lusitaniae afecta principalmente a pacientes inmunocomprometidos, con uso de dispositivos intravasculares y el empleo de antibióticos de amplio espectro. Reporte de caso: Se presenta el caso de un lactante menor quien es diagnosticado con fungemia y endocarditis infecciosa por Candida lusitaniae en válvula nativa posterior a cirugía de corrección por transposición de grandes vasos. Discusión y Conclusiones: La endocarditis infecciosa por Candida lusitaniae es una entidad poco frecuente, con una prevalencia menor al 2% constituyéndose un escenario desafiante en la práctica clínica. Se describen las características de un lactante menor quien presentó endocarditis fúngica ya definidas en la literatura mundial. Es imprescindible la detección temprana y una intervención terapéutica vertiginosa; puesto que, la persistencia del inoculo, la resistencia antimicótica y el retraso en el diagnóstico conllevan a una condición amenazante para la vida del paciente.

Zinc(II) complexes with aromatic nitrogen-containing heterocycles as antifungal agents: Synergistic activity with clinically used drug nystatin

Three novel Zn(II) complexes, [ZnCl₂(qz)₂] (1), [ZnCl₂(1,5-naph)]_n (2) and [ZnCl₂(4,7-phen)₂] (3), where qz is quinazoline, 1,5-naph is 1,5-naphthyridine and 4,7-phen is 4,7-phenanthroline, were synthesized by the reactions of ZnCl₂ and the corresponding N-heterocyclic ligand in 1:2 molar ratio in ethanol at ambient temperature. The characterization of these complexes was done by NMR, IR and UV-Vis spectroscopy, and their crystal structures were determined by single-crystal X-ray diffraction analysis. Complexes 1 and 3 are mononuclear species, in which Zn(II) ion is tetrahedrally coordinated by two nitrogen atoms belonging to two qz or 4,7-phen ligands, respectively, and by two chloride anions, while complex 2 is a 1D coordination polymer that contains 1,5-naph as bridging ligand between two metal ions. In agar disc-diffusion assay, complexes 1-3 manifested good inhibitory activity against two investigated Candida strains (C. albicans and C. parapsilosis), while not inducing toxic effects on the healthy human fibroblast cell line (MRC-5). This activity was not fungicidal, as revealed by the broth microdilution assay, however complex 3 showed the ability to modulate Candida hyphae formation, which is an important process during infection and showed significant synergistic effect with clinically used antifungal polyene nystatin.

Antibiotic saving effect of combination therapy through synergistic interactions between well-characterized chito-oligosaccharides and commercial antifungals against medically relevant yeasts

Combination therapies can be a help to overcome resistance to current antifungals in humans. The combined activity of commercial antifungals and soluble and well-defined low molecular weight chitosan with average degrees of polymerization (DP_n) of 17–62 (abbreviated C17 –C62) and fraction of acetylation (F_A) of 0.15 against medically relevant yeast strains was studied. The minimal inhibitory concentration (MIC) of C32 varied greatly among strains, ranging from > 5000 μg mL^-1 (Candida albicans and C. glabrata) to < 4.9 (C. tropicalis). A synergistic effect was observed between C32 and the different antifungals tested for most of the strains. Testing of several CHOS preparations indicated that the highest synergistic effects are obtained for fractions with a DP_n in the 30–50 range. Pre-exposure to C32 enhanced the antifungal effect of fluconazole and amphotericin B. A concentration-dependent post-antifungal effect conserved even 24 h after C32 removal was observed. The combination of C32 and commercial antifungals together or as part of a sequential therapy opens new therapeutic perspectives for treating yeast infections in humans.

Surgical-site mucormycosis infection in a solid-organ transplant recipient and a concise review of the literature

Surgical-site mucormycosis infections in solid-organ transplant recipients are rare conditions, with only 15 previously reported cases. We describe a case of a 49-year-old man who received a liver transplant due to alcoholic cirrhosis. On postoperative day 14, necrosis was noticed at the surgical site. After mucormycosis was diagnosed, monotherapy with amphotericin was started along with surgical debridements. Due to continued clinical deterioration, triple antifungal therapy was started with amphotericin, micafungin and posaconazole. Treatment with a granulocyte-macrophage colony-stimulating factor was also started. Despite therapy, the patient expired on postoperative day 31. We review the risk factors for mucormycosis infection in solid-organ transplant recipients as well as evidence for current treatment options. We also review the 15 previously reported cases of surgical-site mucormycosis infections in solid-organ transplant recipients, including time to infection, infecting organisms, mortality and treatments.

Anticandidal agent for multiple targets: the next paradigm in the discovery of proficient therapeutics/overcoming drug resistance

Candida albicans is a prominent human fungal pathogen. Current treatments are suffering a massive gap due to emerging resistance against available antifungals. Therefore, there is an ardent need for novel antifungal candidates that essentially have more than one target, as most antifungal repertoires are single-target drugs. Exploration of multiple-drug targeting in antifungal therapeutics is still pending. An extensive literature survey was performed to categorize and comprehend relevant studies and the current therapeutic scenario that led researchers to preferentially consider multitarget drug-based Candida infection therapy. With this article, we identified and compiled a few potent antifungal compounds that are directed toward multiple virulent targets in C. albicans. Such compound(s) provide an optimistic platform of multiple targeting and could leave a substantial impact on the development of effective antifungals.

Inhibition of Vesicular Transport Influences Fungal Susceptibility to Fluconazole

Fungal infections pose a substantial threat to the human population. They can cause either mild and relatively harmless infections or invasive and often lethal diseases in patients with a weakened immune system. The majority of these human fungal infections are caused by Candida species. The limited amount of available therapies, together with the development of resistance against these drugs, strongly emphasizes the need for novel therapeutic strategies. As it is quite time-consuming to introduce completely new drugs to the market, potentiating the efficacy of existing drugs would be a better strategy. Therefore, it is important to identify cellular pathways involved in the development of drug resistance. We found that vesicular transport is involved in fungal susceptibility to the most widely used antifungal drug, fluconazole. We identified specific complexes in the vesicular transport pathway which contribute to fluconazole resistance or tolerance in the model organism Saccharomyces cerevisiae Furthermore, we confirmed our findings in the clinically relevant fungi Candida albicans and Candida glabrata Finally, we show that the combination of fluconazole with a specific inhibitor of the vesicular transport pathway increases the susceptibility of Candida species, indicating the potential of using vesicular transport as a target in combination therapy.

The Frequency of Infective Endocarditis in Candida Bloodstream Infections: a Retrospective Study in a Child Hospital

Introduction

Fungal endocarditis is reported less frequently than bacterial endocarditis, with an incidence of 0-12% of the total pediatric infective endocarditis.

Objective

In this study, the incidence of infective endocarditis in Candida bloodstream infections in a tertiary hospital during the periods of 2007 and 2016 was reviewed.

Methods

Patients with positive blood or catheter cultures in terms of Candida spp. during the study period of January 2007 and January 2016 were analyzed in terms of Candida infective endocarditis. Infective endocarditis was defined according to the modified Duke criteria. The outcome, possible associated predisposing factors for Candida endocarditis were determined.

Results

221 patients and 256 attacks with positive blood or catheter cultures in terms of Candida were included in the study. The most common Candida species was Candida parapsilosis, isolated in 157 (61.3%) attacks, followed by Candida albicans in 70 (27.3%). Neurological diseases (23%), hemato-oncological diseases (12.1%), previously known heart diseases (8.2%), inborn errors of metabolism (9%) were common comorbidities. Twelve (5.4%) patients had a previous history of cardiac surgery. Among the 221 patients, Candida endocarditis was present in only two (0.9%) of them.

Conclusion

Although Candida infective endocarditis is an uncommon but frequently fatal infection in pediatrics, echocardiography should be performed routinely for patients with positive blood or catheter cultures in terms of Candida. Prompt and effective antimicrobial therapy might prevent cardiac surgery in selected cases, however this could not be a general rule for all patients.

In Vitro Characterization of a Biaryl Amide Anti-virulence Compound Targeting Candida albicans Filamentation and Biofilm Formation

We have previously identified a small molecule compound, N-[3-(allyloxy)-phenyl]-4-methoxybenzamide (9029936), that exerts potent inhibitory activity against filamentation and biofilm formation by the Candida albicans SC5314 strain and represents a lead candidate for the development of anti-virulence approaches against C. albicans infections. Here we present data from a series of experiments to further characterize its in vitro activity and drug-like characteristics. We demonstrate the activity of this compound against a panel of C. albicans clinical isolates, including several displaying resistance to current antifungals; as well as against a set of C. albicans gain of function strains in key transcriptional regulators of antifungal drug resistance. The compound also inhibits filamentation and biofilm formation in the closely related species C. dubliniensis, but not C. glabrata or C. tropicalis. Combinatorial studies reveal the potential of compound 9029936 to be used together with currently available conventional antifungals. Results of serial passage experiments indicate that repeated exposure to this compound does not elicit resistance. Viability staining of C. albicans in the presence of high concentrations of compound 9029936 confirms that the compound is not toxic to fungal cells, and cytological staining using image flow cytometry analysis reveals that treatment with the lead compound affects hyphal length, with additional effects on cell wall and integrity of the membrane system. In vitro pharmacological profiling provides further evidence that the lead compound displays a safe profile, underscoring its excellent “drug-like” characteristics. Altogether these results confirm the potential of this compound to be further developed as a true anti-virulence agent for the treatment of C. albicans infections, including those refractory to treatment with conventional antifungal agents.

Antifungal mechanism of action of Schinus lentiscifolius Marchand essential oil and its synergistic effect in vitro with terbinafine and ciclopirox against dermatophytes

OBJECTIVES

The aim of this study was to evaluate the antifungal, antichemotactic and antioxidant activities of Schinus lentiscifolius essential oil, as well as its combined effect with terbinafine and ciclopirox, against dermatophytes.

METHODS

Essential oil was analysed by GC-MS. The antifungal activity and the mechanism of action were determined by broth microdilution, sorbitol and ergosterol assays, as well as scanning electron microscopy. The checkerboard method was used for evaluating the interactions with commercial antifungal agents. The antioxidant and antichemotactic activities were measured using the DPPH and the modified Boyden chamber methods, respectively.

KEY FINDINGS

Chemical analysis revealed the presence of 33 compounds, the primary ones being γ-eudesmol (12.8%) and elemol (10.5%). The oil exhibited 97.4% of antichemotactic activity and 37.9% of antioxidant activity. Antifungal screening showed effect against dermatophytes with minimum inhibitory concentration values of 125 and 250 μg/ml. Regarding the mechanisms of action, the assays showed that the oil can act on the fungal cell wall and membrane. Synergistic interactions were observed using the combination with antifungals, primarily terbinafine.

CONCLUSIONS

Schinus lentiscifolius essential oil acted as a chemosensitizer of the fungal cell to the drug, resulting in an improvement in the antifungal effect. Therefore, this combination can be considered as an alternative for the topical treatment of dermatophytosis.

Caffeic acid phenethyl ester synergistically enhances the antifungal activity of fluconazole against resistant Candida albicans

BACKGROUND

Owing to the increased morbidity and mortality associated with invasive fungal infections, treatments with a combination of antifungal agents are often considered. Caffeic acid phenethyl ester (CAPE), a major active component of propolis, possesses many biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, and anticancer effects.

PURPOSE

This study aimed to evaluate the interaction between CAPE and fluconazole (FLC) against Candida albicans.

METHODS

Microdilution checkerboard and time-kill assays were employed to evaluate the in vitro interaction between CAPE and FLC. The data obtained from the checkerboard tests were analyzed by the fractional inhibitory concentration index (FICI).The antifungal activity of the CAPE and FLC combination was evaluated in vivo in a Caenorhabditis elegans model of infection.

RESULTS

We observed that when used in combination, CAPE acted synergistically with FLC against FLC-resistant clinical isolates of C. albicans. In addition, the CAPE-FLC combination significantly extended the longevity and reduced fungal burden in C. elegans when compared with treatment with FLC or CAPE alone.

CONCLUSION

These results indicate that the use of CAPE and FLC in combination has considerable therapeutic potential against resistant C. albicans.

Bis-guanylhydrazones as efficient anti-Candida compounds through DNA interaction

Candida spp. are leading causes of opportunistic mycoses, including life-threatening hospital-borne infections, and novel antifungals, preferably aiming targets that have not been used before, are constantly needed. Hydrazone- and guanidine-containing molecules have shown a wide range of biological activities, including recently described excellent antifungal properties. In this study, four bis-guanylhydrazone derivatives (BG1-4) were generated following a previously developed synthetic route. Anti-Candida (two C. albicans, C. glabrata, and C. parapsilosis) minimal inhibitory concentrations (MICs) of bis-guanylhydrazones were between 2 and 15.6 μg/mL. They were also effective against preformed 48-h-old C. albicans biofilms. In vitro DNA interaction, circular dichroism, and molecular docking analysis showed the great ability of these compounds to bind fungal DNA. Competition with DNA-binding stain, exposure of phosphatidylserine at the outer layer of the cytoplasmic membrane, and activation of metacaspases were shown for BG3. This pro-apoptotic effect of BG3 was only partially due to the accumulation of reactive oxygen species in C. albicans, as only twofold MIC and higher concentrations of BG3 caused depolarization of mitochondrial membrane which was accompanied by the decrease of the activity of fungal mitochondrial dehydrogenases, while the activity of oxidative stress response enzymes glutathione reductase and catalase was not significantly affected. BG3 showed synergistic activity with amphotericin B with a fractional inhibitory concentration index of 0.5. It also exerted low cytotoxicity and the ability to inhibit epithelial cell (TR146) invasion and damage by virulent C. albicans SC5314. With further developments, BG3 may further progress in the antifungal pipeline as a DNA-targeting agent.

In Vitro Combination of Isavuconazole with Echinocandins against Azole-Susceptible and -Resistant Aspergillus spp

In vitro combinations of isavuconazole with echinocandins were evaluated against 30 Aspergillus strains with a two-dimensional checkerboard microdilution method and an agar-based diffusion method. With the checkerboard method, the three combinations showed indifferent interactions for all strains. With the agar-based method, indifferent interactions were found for all strains for isavuconazole-micafungin and isavuconazole-anidulafungin. For the isavuconazole-caspofungin combination, indifference was found in 24/30 strains, synergism in 4/30 strains, and antagonism in 2/30 strains.

Combination Antifungal Therapy: A Review of Current Data

The incidence of invasive fungal infections has been on the rise, particularly in transplant recipients and in patients with hematological malignancies and other forms of immunosuppression. There is a mismatch between the rate of antifungal resistance and the development of new antifungal agents. Based on this, the idea of combining antifungals in the treatment of invasive fungal infections appears tempting for many clinicians, particularly after many in vitro studies showed synergism between many antifungal agents. Several randomized controlled trials have been published regarding the efficacy and safety of combination of antifungals, but the high cost, the limited number of cases and the multitude of confounding factors lead in some instances to weak and sometimes contradictory results. The lack of consensus in many clinical scenarios raises the importance of the need for more studies about combination antifungal therapies and should incite infectious disease societies to develop specific recommendations for the clinicians to follow while approaching patients with invasive fungal infections.

Reversal of fluconazole resistance induced by a synergistic effect with Acca sellowiana in Candida glabrata strains

CONTEXT

The increased incidence of non-albicans Candida (NAC) resistant to fluconazole (FLZ) makes it necessary to use new therapeutic alternatives. Acca sellowiana (O.berg) Burret (Myrtaceae) is a guava with several proven biological activities. The interaction with fluconazole can be a feasible alternative to overcome this resistance.

OBJECTIVE

This study evaluates the in vitro antifungal activity of fractions obtained from the lyophilized aqueous extract of the leaves of A. sellowiana against resistant strains of NAC.

MATERIALS AND METHODS

The antifungal activity of the fractions was evaluated at 500 μg/mL by microdilution method. Checkerboard assay was performed to determine the effect of the combination of the F2 fraction and antifungal at concentrations: MIC/4, MIC/2, MIC, MIC × 2 and MIC × 4.

RESULTS

Candida glabrata showed the lowest MIC values (500-3.90 μg/mL) and the F2 active fraction was the most effective. The association of F2 with FLZ showed a strong synergistic effect (FICI ≤ 0.5) against 100% of C. glabrata resistant isolates. Moreover, the F2 active fraction has demonstrated that probably acts in the cell wall of these yeasts. There was no observed acute dermal toxicity of lyophilized aqueous extract of leaves of A. sellowiana on pig ear skin cells.

DISCUSSION AND CONCLUSION

The interaction between substances present in the F2 active fraction is possibly responsible for the antifungal activity presented by this fraction. This study is unprecedented and suggests that the combination of F2 active fraction and FLZ might be used as an alternative treatment for mucocutaneus infections caused by C. glabrata resistant.

Synergistic effect of pedalitin and amphotericin B against Cryptococcus neoformans by in vitro and in vivo evaluation

Cryptococcosis is an opportunistic fungal infection responsible for high morbidity and mortality in immunocompromised patients. Combination of antifungal substances is a promising way to increase the percentage of successful treatment. Pedalitin (PED) is a natural substance obtained from Pterogyne nitens. The aim of this study was to verify the efficacy of PED alone and in combination with amphotericin B (AmB) in vitro and in vivo against Cryptococcus spp. In the in vitro assay, minimum inhibitory concentrations (MICs) of 0.125 mg/L for AmB and 3.9 mg/L for PED were found when the substances were tested alone, whilst in the combination treatment the active concentration of both decreased, with MICs of 0.03 mg/L for AmB and 1 mg/L for PED. In the survival assay, fungal burden study and histopathological assays it was possible to study the efficacy of the substances alone and in combination. The efficacy of combination therapy was considered better than monotherapy as evaluated in a Galleria mellonella model and a murine model. Thus, the combination of PED and AmB is an interesting alternative for anticryptococcal fungal treatment. Moreover, a correlation was observed between the invertebrate and murine models for this antifungal treatment combination.

Synergistic combinations of antifungals and anti-virulence agents to fight against Candida albicans

Candida albicans, one of the pathogenic Candida species, causes high mortality rate in immunocompromised and high-risk surgical patients. In the last decade, only one new class of antifungal drug echinocandin was applied. The increased therapy failures, such as the one caused by multi-drug resistance, demand innovative strategies for new effective antifungal drugs. Synergistic combinations of antifungals and anti-virulence agents highlight the pragmatic strategy to reduce the development of drug resistant and potentially repurpose known antifungals, which bypass the costly and time-consuming pipeline of new drug development. Anti-virulence and synergistic combination provide new options for antifungal drug discovery by counteracting the difficulty or failure of traditional therapy for fungal infections.

Flucytosine Pharmacokinetics in a Critically Ill Patient Receiving Continuous Renal Replacement Therapy

Purpose. A case report evaluating flucytosine dosing in a critically ill patient receiving continuous renal replacement therapy. Summary. This case report outlines an 81-year-old male who was receiving continuous venovenous hemofiltration (CVVH) for acute renal failure and was being treated with flucytosine for the treatment of disseminated Cryptococcus neoformans infection. Due to patient specific factors, flucytosine was empirically dose adjusted approximately 50% lower than intermittent hemodialysis (iHD) recommendations and approximately 33% lower than CRRT recommendations. Peak and trough levels were obtained, which were supratherapeutic, and pharmacokinetic parameters were calculated. The patient experienced thrombocytopenia, likely due to elevated flucytosine levels, and flucytosine was ultimately discontinued. Conclusion. Despite conservative flucytosine dosing for a patient receiving CVVH, peak and trough serum flucytosine levels were supratherapeutic (120 μg/mL at 2 hours and 81 μg/mL at 11.5 hours), which increased drug-related adverse effects. The results indicate that this conservative dosing regimen utilizing the patient's actual body weight was too aggressive. This case report provides insight into flucytosine dosing in CVVH, a topic that has not been investigated previously. Further pharmacokinetic studies of flucytosine dosing in critically ill patients receiving CVVH are needed in order to optimize pharmacokinetic and pharmacodynamic parameters while avoiding toxic flucytosine exposure.

Isolated pulmonary valve infective endocarditis in a middle aged man caused by Candida albicans: a case report

Background

Pulmonary valve endocarditis without the involvement of other valves represents 1.5-2% of all cases of infective endocarditis. Isolated pulmonary valve endocarditis caused by Candida is extremely rare with only one reported case in the literature and none reported in the United States. Guidelines for management of Candida endocarditis recommend a combination of medical and surgical therapy.

Case presentation

A 61-year-old homeless male presented with fever, cough and shortness of breath. He was urgently intubated for hypoxia. He was initially diagnosed with pneumonia but did not improve with empiric antibacterial therapy. Candida species were isolated from bronchoalveolar lavage fluid and the patient eventually developed persistent C. albicans bloodstream infection. On further workup he was found to have infective endocarditis with a large vegetation across the pulmonary valve. No other valves were involved. He was treated with intravenous antifungal therapy for eight weeks. Valvular surgery was not performed. Follow up echocardiography after completion of therapy did not show any vegetations and the patient clinically improved.

Conclusion

This is the second reported case of isolated pulmonary valve endocarditis caused by Candida and the first to be successfully managed with antifungal therapy alone. Pulmonary valve endocarditis should be considered in cases of pneumonia with Candida and persistent fungemia. While surgery should be considered in all cases of Candida endocarditis, cure may be achieved with antifungal therapy alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0557-5) contains supplementary material, which is available to authorized users.

[Pulmonary aspergillosis in a non-immunocompromised critically ill patient]

BACKGROUND

In non-immunocompromised patients admitted to intensive care departments or units (ICU), it is difficult to establish a definitive diagnosis of pulmonary aspergillosis because the signs and symptoms of this infectious disease are non-specific, and serological techniques are not very specific as well. For this reason, a diagnosis of possible pulmonary aspergillosis is initially established, and the starting of the treatment is controversial.

CASE REPORT

An immunocompetent subject had a work-related accident after a fall, which resulted in multiple injuries (head, thorax, lower extremities). The patient required mechanical ventilation since admission. On the second week of ICU admission, he showed a clinical presentation of respiratory infection with fever, purulent secretions, bilateral pulmonary infiltrates and repeated isolation of Mucor and Aspergillus fumigatus in bronchial secretions and pharyngeal swabs. The patient was treated with amphotericin B lipid complex and voriconazole with an excellent clinical and radiological outcome.

CONCLUSIONS

Combined treatment of antifungal agents, in this case amphotericin B lipid complex and voriconazole, is a therapeutic possibility to be considered in patients who failed to respond to initial antifungal monotherapy.

Evaluation of combination effects of ethanolic extract of Ziziphus mucronata Willd. subsp. mucronata Willd. and antibiotics against clinically important bacteria

A pragmatic approach to the treatment of infectious diseases with multicausal agents and prevention of the development of resistant isolates is the combination of herbal remedies with the first-line antimicrobial agents to which most of them have become resistant. This study evaluated the interactions between the ethanolic bark extract of Ziziphus mucronata with known antimicrobial agents in vitro. In this study, the results showed that varied zones of inhibitions (ZME-chloramphenicol (17-42 mm), ZME-amoxicillin (17-35 mm), ZME-tetracycline (17-36 mm), ZME-ciprofloxacin (20-41 mm), ZME-nalidixic acid (17-34 mm), and ZME-kanamycin (17-38 mm)) were produced by the antibacterial combinations. At the highest combined concentrations, 12 isolates (ZME-ciprofloxacin) > 10 isolates (ZME-chloramphenicol) = (ZME-kanamycin) > 6 isolates (ZME-amoxicillin) = (ZME-nalidixic acid) and 5 isolates (ZME-tetracycline) were inhibited with zones of inhibition greater than 20 ± 1.0 mm. Although the agar diffusion assay suggested that the interactions between the ethanolic extract of Z. mucronata and the antibiotics were both synergistic and additive in nature, the fractional inhibitory concentration indices (FICI) showed that the interactions were synergistic (54.17%), additive (27.78%), indifferent (16.67%), and antagonistic (1.39%). While the fractional inhibitory concentration indices (FICIs) for synergism ranged between 0.00391 and 0.5, that of additivity ranged between 0.516 and 1.0, indifferences ranged between 1.062 and 3.0 and antagonistic interaction was 5.0. The synergistic effects implied that the antibacterial combinations would be more effective and useful in the treatment of multicausal and multidrug-resistant bacteria than a single monotherapy of either antibacterial agent.

Novel method for evaluating in vitro activity of anidulafungin in combination with amphotericin B or azoles

A combination of drugs possessing different targets has been used as salvage therapy, although without scientific support. In vitro studies validating such combinations are scarce, and the methodology is very laborious and time-consuming. This study proposes a flow cytometric (FC) protocol as an alternative to evaluate the effect of the combination of anidulafungin (AND) with amphotericin B (AMB) and azoles (fluconazole and voriconazole), tested upon 39 and 36 Candida strains, respectively. The concentration assayed in the combination was 0.5× MIC of each drug. The membrane potential marker DiBAC(4)(3) [Bis-(1,3-dibutylbarbituric acid) trimethine oxonol] was used for AND-AMB, and the metabolic marker FUN-1 was used for AND-azoles. Drug interaction was determined by calculating a staining index (SI): the sum of the percentage of depolarized cells (DC) after treatment with drug combinations divided by the DC of the drug alone, and the sum of the mean intensity of fluorescence (MIF) displayed by cells treated with drug combinations divided by the MIF of the drug alone for FUN-1. An SI of <1 means antagonism, an SI between 1 and 4 means no interaction, and an SI of >4 means synergism. The combination of AND and AMB by FC and checkerboard was synergistic for 46 and 43% of isolates and antagonistic for 5 and 8%, respectively. For the combination of AND and azoles, it was synergistic for 36% and antagonistic for 3% by FC and synergistic for 44% and antagonistic for 3% by checkerboard. When the FC method was compared to the gold standard checkerboard method, the agreement was 0.91 (95% confidence interval [95% CI] of 0.88 to 0.94), sensitivity was 0.88 (95% CI of 0.73 to 0.95), and specificity was 0.95 (95% CI of 0.84 to 1). Thus, FC is a rapid and reliable method (<2 h) to assess the effect of antifungal combinations.

Chemosensitization as a means to augment commercial antifungal agents

Antimycotic chemosensitization and its mode of action are of growing interest. Currently, use of antifungal agents in agriculture and medicine has a number of obstacles. Foremost of these is development of resistance or cross-resistance to one or more antifungal agents. The generally high expense and negative impact, or side effects, associated with antifungal agents are two further issues of concern. Collectively, these problems are exacerbated by efforts to control resistant strains, which can evolve into a treadmill of higher dosages for longer periods. This cycle in turn, inflates cost of treatment, dramatically. A further problem is stagnation in development of new and effective antifungal agents, especially for treatment of human mycoses. Efforts to overcome some of these issues have involved using combinations of available antimycotics (e.g., combination therapy for invasive mycoses). However, this approach has had inconsistent success and is often associated with a marked increase in negative side effects. Chemosensitization by natural compounds to increase effectiveness of commercial antimycotics is a somewhat new approach to dealing with the aforementioned problems. The potential for safe natural products to improve antifungal activity has been observed for over three decades. Chemosensitizing agents possess antifungal activity, but at insufficient levels to serve as antimycotics, alone. Their main function is to disrupt fungal stress response, destabilize the structural integrity of cellular and vacuolar membranes or stimulate production of reactive oxygen species, augmenting oxidative stress and apoptosis. Use of safe chemosensitizing agents has potential benefit to both agriculture and medicine. When co-applied with a commercial antifungal agent, an additive or synergistic interaction may occur, augmenting antifungal efficacy. This augmentation, in turn, lowers effective dosages, costs, negative side effects and, in some cases, countermands resistance.

Fungal infections: their diagnosis and treatment in transplant recipients

Systemic fungal infections typically occur in individuals who are seriously ill with recognized risk factors such as those frequently found in transplant recipients. Unfortunately, they are often diagnosed late, when the efficacy of the available treatments is low, often less than 50%, and the cost in terms of lives lost, hospital length of stay, and total hospital costs is substantially increased. The application of antifungal therapies associated with reported efficacy rates greater than 50% are those used prophylactically. When used prophylactically, these infections are reduced in greater than 95% of the expected cases. The choice of a prophylactic agent should be based upon its ease of administration, lack of adverse effects, reduced likelihood of potential drug interactions, and its efficacy in patients with established risk factors and comorbid disease processes that include renal, hepatic, and chronic pulmonary disease. The indications for the use of currently available antifungal agents, their adverse effects, drug interactions, ease of dosing, and applicability in patients with preexisting disease states, and especially in liver transplant recipients, are presented in this paper.

A flucytosine-responsive Mbp1/Swi4-like protein, Mbs1, plays pleiotropic roles in antifungal drug resistance, stress response, and virulence of Cryptococcus neoformans

Cryptococcosis, caused by the basidiomycetous fungus Cryptococcus neoformans, is responsible for more than 600,000 deaths annually in AIDS patients. Flucytosine is one of the most commonly used antifungal drugs for its treatment, but its resistance and regulatory mechanisms have never been investigated at the genome scale in C. neoformans. In the present study, we performed comparative transcriptome analysis by employing two-component system mutants (tco1Δ and tco2Δ) exhibiting opposing flucytosine susceptibility. As a result, a total of 177 flucytosine-responsive genes were identified, and many of them were found to be regulated by Tco1 or Tco2. Among these, we discovered an APSES-like transcription factor, Mbs1 (Mbp1- and Swi4-like protein 1). Expression analysis revealed that MBS1 was regulated in response to flucytosine in a Tco2/Hog1-dependent manner. Supporting this, C. neoformans with the deletion of MBS1 exhibited increased susceptibility to flucytosine. Intriguingly, Mbs1 played pleiotropic roles in diverse cellular processes of C. neoformans. Mbs1 positively regulated ergosterol biosynthesis and thereby affected polyene and azole drug susceptibility. Mbs1 was also involved in genotoxic and oxidative stress responses. Furthermore, Mbs1 promoted production of melanin and capsule and thereby was required for full virulence of C. neoformans. In conclusion, Mbs1 is considered to be a novel antifungal therapeutic target for treatment of cryptococcosis.

Comparison of echinocandin antifungals

The incidence of invasive fungal infections, especially those due to Aspergillus spp. and Candida spp., continues to increase. Despite advances in medical practice, the associated mortality from these infections continues to be substantial. The echinocandin antifungals provide clinicians with another treatment option for serious fungal infections. These agents possess a completely novel mechanism of action, are relatively well-tolerated, and have a low potential for serious drug-drug interactions. At the present time, the echinocandins are an option for the treatment of infections due Candida spp (such as esophageal candidiasis, invasive candidiasis, and candidemia). In addition, caspofungin is a viable option for the treatment of refractory aspergillosis. Although micafungin is not Food and Drug Administration-approved for this indication, recent data suggests that it may also be effective. Finally, caspofungin- or micafungin-containing combination therapy should be a consideration for the treatment of severe infections due to Aspergillus spp. Although the echinocandins share many common properties, data regarding their differences are emerging at a rapid pace. Anidulafungin exhibits a unique pharmacokinetic profile, and limited cases have shown a potential far activity in isolates with increased minimum inhibitory concentrations to caspofungin and micafungin. Caspofungin appears to have a slightly higher incidence of side effects and potential for drug-drug interactions. This, combined with some evidence of decreasing susceptibility among some strains of Candida, may lessen its future utility. However, one must take these findings in the context of substantially more data and use with caspofungin compared with the other agents. Micafungin appears to be very similar to caspofungin, with very few obvious differences between the two agents.

Multilaboratory testing of two-drug combinations of antifungals against Candida albicans, Candida glabrata, and Candida parapsilosis

There are few multilaboratory studies of antifungal combination testing to suggest a format for use in clinical laboratories. In the present study, eight laboratories tested quality control (QC) strain Candida parapsilosis ATCC 22019 and clinical isolates Candida albicans 20533.043, C. albicans 20464.007, Candida glabrata 20205.075, and C. parapsilosis 20580.070. The clinical isolates had relatively high azole and echinocandin MICs. A modified CLSI M27-A3 protocol was used, with 96-well custom-made plates containing checkerboard pairwise combinations of amphotericin B (AMB), anidulafungin (AND), caspofungin (CSP), micafungin (MCF), posaconazole (PSC), and voriconazole (VRC). The endpoints were scored visually and on a spectrophotometer or enzyme-linked immunosorbent assay (ELISA) reader for 50% growth reduction (50% inhibitory concentration [IC(50)]). Combination IC(50)s were used to calculate summation fractional inhibitory concentration indices (FICIs) (ΣFIC) based on the Lowe additivity formula. The results revealed that the IC(50)s of all drug combinations were lower or equal to the IC(50) of individual drugs in the combination. A majority of the ΣFIC values were indifferent (ΣFIC = 0.51 to 2.0), but no antagonism was observed (ΣFIC ≥ 4). Synergistic combinations (ΣFIC ≤ 0.5) were found for AMB-PSC against C. glabrata and for AMB-AND and AMB-CSP against C. parapsilosis by both visual and spectrophotometric readings. Additional synergistic interactions were revealed by either of the two endpoints for AMB-AND, AMB-CSP, AMB-MCF, AMB-PSC, AMB-VRC, AND-PSC, CSP-MCF, and CSP-PSC. The percent agreements among participating laboratories ranged from 37.5% (lowest) for AND-CSP and POS-VOR to 87.5% (highest) for AMB-MCF and AND-CSP. Median ΣFIC values showed a wide dispersion, and interlaboratory agreements were less than 85% in most instances. Additional studies are needed to improve the interlaboratory reproducibility of antifungal combination testing.