Aerosolized Antifungals for the Prevention and Treatment of Invasive Fungal Infections

Invasive fungal infections result in significant morbidity and mortality, most notably in immunosuppressed patients. Aerosolized antifungal agents have been utilized primarily as prophylaxis (either alone or in combination with systemic antifungals) in patients at highest risk of invasive infections in attempts to optimize drug delivery while minimizing the potential for systemic toxicity and/or drug interactions. Published clinical experience with aerosolized antifungals most frequently involves various formulations of the polyene amphotericin B in patients undergoing lung transplantation and/or select patients with hematologic malignancy. Adverse events are infrequent and generally limited to dyspnea, dysgeusia, and cough. Existing data suggests lipid-based amphotericin B formulations may be better tolerated than amphotericin B deoxycholate. Published clinical experience with aerosolized antifungals as adjunctive treatment of invasive fungal infections is limited to case reports. Currently, there is insufficient evidence to support use of aerosolized echinocandins and azoles in clinical practice. Outstanding questions regarding comparative efficacy, optimal dose, duration and drug delivery present a continuing challenge when utilizing these agents in clinical practice.     

Direct comparison of the pharmacodynamics of four antifungal drugs in a mouse model of disseminated candidiasis using microbiological assays of serum drug concentrations

The aim of this study was to compare the pharmacodynamics of the azole antifungal drugs fluconazole, itraconazole and ketoconazole, and the polyene antifungal amphotericin B, in a mouse model of disseminated Candida albicans infection. In order to directly compare effective serum concentrations of these antifungals, drug concentrations were assayed microbiologically by measuring inhibition of C. albicans mycelial growth (mMIC) in a mouse serum-based assay (serum antifungal titer). Efficacy in the mouse infection model was determined using an organ-based (kidney burden) endpoint. For all four drugs, the serum antifungal titers, 8 hr after administration of single doses of drugs at a range of drug concentrations, correlated closely with C. albicans kidney fungal burden in the mouse model. The results showed that determining serum antifungal titer may be used to accurately represent kidney fungal burden in a mouse model of disseminated candidiasis and allowed direct comparison of the pharmacodynamics of differing classes of antifungal drugs.     

Therapeutic efficacy of anidulafungin for the treatment of oesophageal candidiasis, candidemia and invasive candidiasis

Anidulafungin is a new echinocandin that appears to have several advantages over existing antifungals. It is unique because it slowly degrades in humans, undergoing a process of biotransformation rather than being metabolized. It exhibits high in vitro and in vivo activities against Candida spp. and Aspergillus spp. In several clinical studies investigating Candida esophagitis; candidemia and invasive candidiasis, the clinical efficacy of this echinocandin was similar, or even superior, to that of established antifungals in candidemia. Antifungal activity against strains no longer susceptible to conventional antifungal agents, such as fluconazole and amphotericin B suggests that anidulafungin can be used as salvage therapy in life-threatening fungal infections. The limited toxicity profile, minimal drug-drug interactions and the fact that does not require dosage adjustment in subjects with hepatic or renal impairment, establishes this echinocandin as an attractive new option for the treatment of invasive fungal infections.     

Are Echinocandins Better Than Azoles for Invasive Candidiasis?

Antifungal therapy has advanced tremendously in the past decade, with multiple new agents for systemic fungal infections that have a broad spectrum of activity and are well-tolerated. There is usually more than one acceptable therapeutic option for many diseases, and this is true in particular of candidiasis. Fluconazole has been the drug of choice for most clinical syndromes of candidiasis, due to its tolerability, effectiveness, and ease of administration. However, the echinocandin class of antifungals, comprised of caspofungin, micafungin and anidulafingin, has emerged as the preferred choice in the therapy of invasive candidiasis and candidemia. Their potent fungicidal activity and minimal toxicity have made them first-line drugs for this indication. In certain clinical settings, they may even be agents of first choice. Nevertheless, recent trends in echinocandin resistance demonstrated with Candida glabrata mandate ongoing surveillance, and continued trends may impact upon future antifungal selection.     

THIS ARTICLE HAS BEEN RETRACTEDHamycin treatment of candidiasis in normal and diabetic rats

Hamycin, a heptaene antifungal antibiotic was compared with amphotericin B in the treatment of established systemic infection with Candida albicans in normal and diabetic rats. In normal rats, orally administered hamycin at 10 mg kg(-1) per day for 7 days reduced Candida colony counts in the kidneys and livers as well as amphotericin B did and was nearly as effective as amphotericin B in a 21-day treatment trial. There was no further reduction in Candida colony counts when normal rats were treated with hamycin at 25 mg kg(-1) twice a day for 7 days. In streptozotocin induced diabetic rats, hamycin at 20 mg kg(-1) per day for either 7 or 21 days compared favourably with amphotericin B in efficacy. Results of the present study suggest that oral hamycin may be useful in the treatment of established disseminated candidiasis in normal as well as diabetic hosts.     

Invasive infections due to Clavispora lusitaniae

Three cases of Clavispora lusitaniae invasive fungal infections are reported. All three infections appeared in cancer patients presented with fungaemia, one additionally with meningitis. Two of them were breakthrough -- they developed during therapy with conventional amphotericin B with a dose of 0.5 mg kg(-1) day(-1) . All three were cured: two with intravenous fluconazol and one with an increasing dose (1 mg kg(-1) day(-1)) of amphotericin B. In one of two breakthrough cases the sensitivity of the strain to antifungals was tested against antifungal agents and showed in vitro resistance to amphotericin B (MIC 2 eta g ml(-1)).     

Antifungal Therapy for Invasive Fungal Diseases in Allogeneic Stem Cell Transplant Recipients: An Update

Invasive fungal diseases (IFDs) remain a major cause of morbidity and mortality in allogeneic stem cell transplant (SCT) recipients. While the most common pathogens are Candida spp. and Aspergillus spp., the incidence of infections caused by non-albicans Candida species as well as molds such as Zygomycetes has increased. For many years, amphotericin B deoxycholate (AMB-D) was the only available antifungal for the treatment of IFDs. Within the past decade, there has been a surge of new antifungal agents developed and added to the therapeutic armamentarium. Lipid-based formulations of amphotericin B provide an effective and less nephrotoxic alternative to AMB-D. Voriconazole has now replaced AMB-D as first choice for primary therapy of invasive aspergillosis (IA). Another extended-spectrum triazole, posaconazole, also appears to be a promising agent in the management of zygomycosis, refractory aspergillosis, and for prophylaxis. Members of the newest antifungal class, the echinocandins, are attractive agents in select infections due to their safety profile, and are a more attractive option compared to AMB-D as initial treatment for invasive candidiasis and (based on one study) challenge fluconazole for superiority in management with this mycoses. However, challenges do exist among these newer agents in very high-risk individuals like allogeneic SCT recipients, which may include adverse drug events, drug–drug interactions, variability in oral absorption, and availability of alternative formulations. The addition of newer agents has also stimulated interest in the potential application of combination therapy in serious, life-threatening infections. However, adequate studies are not available for most IFDs; thus, the clinical use of combination therapy is not evidenced based on most cases and preciseness in its use is uncertain. Finally, therapeutic drug monitoring of select antifungals (notably posaconazole and voriconazole) may play an increasing role due to significant interpatient variability in serum concentrations after standard doses.     

In vitro and in vivo evaluation of the antifungal activity of fluoxetine combined with antifungals against Candida albicans biofilms and oral candidiasis

Abstract

Candida albicans biofilms are responsible for oral candidiasis. Fluoxetine is a widely used antidepressant, with certain anti-Candida activities. The antifungal activity of fluoxetine combined with various antifungals against C. albicans biofilms and oral candidiasis was evaluated in this study. The morphological change in the inhibition of fluoxetine on C. albicans biofilms was observed using SEM. The interactions between fluoxetine and antifungals against C. albicans biofilms were evaluated using microdilution checkerboard methods, FICI and the ΔE model. The synergistic combination was tested in vivo on the mice model of oral candidiasis. SEM imaging showed fluoxetine inhibited hyphal growth and biofilm formation. Fluoxetine combined with caspofungin exhibited synergistic effects against C. albicans biofilms. Antagonistic effects occurred when fluoxetine was combined with amphotericin B or terbinafine. Further, the fluoxetine combined with caspofungin significantly reduced the lesion score and CFU of C. albicans on the murine tongue (p?<?0.05), and relieved oral candidiasis of the infected mice.     

白色念珠菌的临床分布及Rosco纸片法药敏结果分析

目的了解目前白色念珠菌的临床分布及其耐药现状,以加强抗真菌药物的合理应用。方法采用Rosco纸片扩散法检测2005年2—9月安徽医科大学第一附属医院临床分离的260株白色念珠菌对7种抗真菌药物的药敏结果。结果白色念珠菌的临床分布以痰液标本为主,老年患者居多。白色念珠菌对制霉菌素、两性霉素B和伊曲康唑的敏感率均较高,分别为98.9％、96．9％和94．2％;其次为酮康唑和氟康唑,敏感率分别为84．6％和82．3％;灰黄霉素、益康唑和眯康唑的敏感率较低,分别为73．9％、57．8％和57．6％。结论临床微生物实验室要加强对白色念珠菌的分离培养和药敏试验,指导临床合理用药,有效控制和减少真菌感染。     

Drug sensitivity of Candida in patients with kidney diseases receiving immunosuppressive therapy

It was shown that prednisolone and its combination with azathioprine++ increased contamination of the patients with yeast-like fungi and promoted development of candidiasis in them to a greater extent than cyclophosphamide. In the patients treated with the immunodepressants there was observed a carrier state in regard to various yeast-like fungi: 12 species belonging to 6 genera were isolated from the pathological materials. Determination of sensitivity to antifungal drugs in 200 Candida strains revealed that amphotericin B was the most active agent. Then followed mycoheptin, nystatin and nitroxolin. Levorin was the least active drug. The MICs of the drugs for the majority of the cultures were 0.5, 4-8, 8-16 and 32-64 micrograms/ml respectively. Candida resistant strains (mainly to levorin and mycoheptin) were isolated only from recipients of kidney transplants during the early postoperative period when the patients were subjected to intensive immunodepressive and prophylactic antifungal therapy. Among the fungi of the Candida genus C. guillermondii and C. parapsilosis proved to be the most resistant. Under the hospital conditions and in vitro studies it was found that cyclophosphamide and combinations of prednisolone with cytostatics increased resistance of Candida to the antifungal drugs. Rapid increasing of the fungi resistance to levorin and mycoheptin was observed. The increase in the resistance to amphotericin B was somewhat lower and that to nitroxolin and nystatin was extremely low. The study of the combined effect of the immunodepressants and antifungal drugs demonstrated that the immunodepressants increased the antifungal activity of amphotericin B, levorin and nitroxolin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Meta-analysis of prophylactic or empirical antifungal treatment versus placebo or no treatment in patients with cancer complicated by neutropenia.

OBJECTIVE: To determine whether antifungal agents given prophylactically or empirically decrease morbidity and mortality in patients with cancer complicated by neutropenia. DESIGN: Meta-analysis of randomised trials of amphotericin B, various lipid soluble formulations of amphotericin B (for example, AmBisome), fluconazole, ketoconazole, miconazole, or itraconazole compared with placebo or no treatment. SETTING: Trials conducted anywhere in the world. SUBJECTS: Patients with cancer complicated by neutropenia. MAIN OUTCOME MEASURES: Mortality, invasive fungal infection (defined as positive blood culture, oesophageal candidiasis, or lung or deep tissue infection), and colonisation. RESULTS: 24 trials with 2758 randomised patients were reviewed; the total number of deaths was 434. Prophylactic or empirical treatment with antifungals as a group bad no effect on mortality (odds ratio 0.92; 95% confidence interval 0.74 to 1.14). Amphotericin B decreased mortality significantly (0.58; 0.37 to 0.93) but the studies were small and the difference in number of deaths was only 15. Antifungal treatment decreased the incidence of invasive fungal infection (0.47; 0.35 to 0.64) and fungal colonisation (0.45; 0.30 to 0.69). For every 73 patients treated (95% confidence interval to 48 to 158) one case of fungal invasion was prevented in surviving patients. CONCLUSIONS: There seems to be no survival benefit of antifungal agents given prophylactically or empirically to patients with cancer complicated by neutropenia. These agents should be restricted to patients with proved infection and those in randomised trials. A large, definitive placebo controlled trial of amphotericin B is needed.     

Biofilm Formation and its Impact on Antifungal Therapy

Fungi can protect themselves from host defences and antifungal drugs by the production of an extracellular hydrophobic matrix. Candida biofilms exhibit resistance to antifungal agents from all classes including the azoles, echinocandins, amphotericin B complex, and flucytosine. Although demonstrated on polystyrene and bronchial epithelia cells, until today, only indirect evidence for A. fumigatus biofilms in patients is available. The antifungals with the most activity against biofilms are the liposomal formulation of amphotericin B and agents in the echinocandin drug class. Importantly, echinocandins show excellent anti-biofilm activity against C. albicans at therapeutic concentrations. However, other biofilms formed by moulds, including A. fumigatus, are relatively resistant to echinocandins. Multiple mechanisms contribute to the intrinsic and acquired antifungal resistance during the different stages of fungal biofilm development. During the growth phase of the early biofilm various factors account for biofilm resistance. Combinational and sequential antifungal therapy as well as combination with enhancers can improve the effect of a single drug. Further studies are warranted to develop new therapeutic strategies targeting fungal biofilm-specific resistance mechanisms.     

Fluorescence method for determining the mechanism and speed of action of surface-active drugs on yeast cells

New antifungal agents are needed to treat life-threatening fungal infections, particularly with the development of resistance. Surface-active antifungals have the advantages of minimizing host toxicity and the emergence of drug resistance. We have developed a time-dependent drug exposure assay that allows us to rapidly investigate the mechanism of surface-active antifungal drug action. The assay uses a multidrug pump-deficient strain of Saccharomyces cerevisiae and the potentiometric dye 3,3'-dipropylthiacarbocyanine iodide [diS-C?(3)] and can assess whether cells are depolarized, hyperpolarized, or permeabilized by drug exposure. In this work, we investigated the mechanisms of action of five surface-active compounds: SDS, nystatin, amphotericin B, octenidine dihydrochloride, and benzalkonium chloride. The diS-C?(3) time-dependent drug exposure assay can be used to identify the mechanisms of action of a wide range of drugs. It is a fast and cost-effective method for screening drugs to determine their lowest effective concentrations.     

Fluconazole and itraconazole susceptibility of vaginal yeast isolates from Slovakia

Vulvovaginal candidiasis is a common mucosal infection caused by opportunistic yeasts of the Candida genus. In this study, we isolated and identified the yeast species in the vagina of patients treated in the gynecology clinic and tested in vitro activities of fluconazole and itraconazole against 227 clinical yeast isolates by the NCCLS microdilution method. C. albicans (87.6%) was the most frequently identified species followed by C. glabrata (6.2%) and C. krusei (2.2%). Almost thirteen percent of yeast strains were resistant to fluconazole and 18.5% were resistant to itraconazole. Cross-resistance analyses of C. albicans isolates revealed that fluconazole resistance and itraconazole resistance were also associated with decreased susceptibilities to other azole derivatives mainly to ketoconazole and miconazole. At the same time no cross-resistance to polyene antibiotics amphotericin B and nystatin was observed. These results support the notion that antifungal agents used to treat vaginitis may be contributing to the drug resistance problem by promoting cross-resistance to a range of clinically used antifungals.     

Effect of Rapid Intravenous Infusion on Serum Concentrations of Amphotericin B

The magnitude of the concentrations of amphotericin B produced in serum of patients with systemic mycoses may significantly influence the outcome of therapy with this drug. Since amphotericin B is conventionally administered in intravenous infusions lasting 4 to 6 hr, we asked whether faster infusions of this drug might yield higher serum concentrations without an increase in dose. This question was studied in three patients who received 16 infusions of this drug: eight infusions administered slowly (5 hr) and eight administered rapidly (45 min). Serum concentrations after each rapid infusion were compared with those after a slow infusion administered to the same patient. The mean serum concentration of amphotericin B 1 hr after the rapid infusions (2.02 mug/ml) was significantly higher (P < 0.001) than the mean serum concentration of amphotericin B 1 hr after the slow infusions of this drug (1.18 mug/ml). Mean serum concentrations 18 and 42 hr after rapid infusion remained slightly but not significantly higher than respective mean concentrations after slow infusions. By yielding higher initial serum concentration, rapid intravenous infusion may be therapeutically more effective than slow infusion of amphotericin B. Although rapid infusions caused no more toxicity than did slow infusions, the lack of greater toxicity with rapid infusion of amphotericin B should be further documented prior to extensive clinical application of this procedure.     

Disseminated candidiasis: evidence of a distinctive syndrome in heroin abusers.

Seven young men developed similar manifestations of disseminated candidiasis after a single episode of intravenous heroin abuse. Sequential development of lesions of the eye, skin, and bone or costal cartilage was noted within 10 days after injection. Skin lesions were confined to the scalp and other hair bearing areas. Candida albicans was cultured readily from affected skin and costal cartilage. Histological examination of scalp biopsy specimens showed infiltration of hair follicles with chronic inflammatory cells and C albicans. Pseudohyphas of C albicans were also identified in and around hair shafts. The skin, skeletal, and small eye lesions resolved on systemic treatment with 1 g amphotericin B plus flucytosine. Pars plana vitrectomy plus local instillation of amphotericin B cured progressive chorioretinitis. These features may represent a distinctive syndrome of disseminated candidiasis in heroin abusers. Systemic antifungal treatment is curative in most cases.     

Phenotype and genotype of Candida albicans strains isolated from pregnant women with recurrent vaginitis

Fourteen out of 80 pregnant women receiving prenatal care presented signs and symptoms of recurrent vaginal candidiasis. Candida albicans strains were isolated from 12 patients (85.7%), and these were submitted to morphotyping (morphological characteristics of the colony), antifungal typing (pattern of sensitivity to amphotericin B, 5-fluorcytosine, myconazole, ketoconazole and fluconazole) and genotyping (electrophoretic migration of DNA fragments digested with EcoRI and HinfI). Alteration of morphotype and antifungal type was observed in 50% of the patients, but the genotype of the strains isolated from the same patients at different times was identical in all subjects. The predominant morphotypes presented continuous fringes and the basic changes observed among antifungal types was the emergence of strains resistant to myconazole, which was the drug used for the treatment of the first episode of vaginitis. We conclude that recurrent vaginal candidiasis is caused by the persistence of a single yeast genotype that undergoes morphological and behavioral changes in the presence of antifungal agents due to the selective pressure to which it is submitted. This revised version was published online in August 2006 with corrections to the Cover Date.     

Antifungal activity of immunosuppressants used alone or in combination with fluconazole

Fungal infections remain a challenge to clinicians due to the limited available antifungals. With the increasing use of antifungals in clinical practice, drug resistance has been emerging continuously, especially to fluconazole (FLC). Thus, a search for new antifungals and approaches to overcome antifungal resistance is needed. However, the development of new antifungals is usually costly and time consuming; discovering the antifungal activity of non-antifungal agents is one way to address these problems. Interestingly, some researchers have demonstrated that several classes of immunosuppressants (calcineurin inhibitors, glucocorticoids, etc) also displayed potent antifungal activity when used alone or in combination with antifungals, especially with FLC. Some of them could increase FLC's susceptibility against resistant Candida albicans significantly reversing fungal resistance to FLC. This article reviews the antifungal activities of immunosuppressants used alone or in combination with antifungals and their potential antifungal mechanisms that have been discovered so far. Although immunosuppressive agents have been identified as risk factors for fungal infection, we believe these findings are very important for overcoming drug resistance and developing new antifungals.     

In?vitro and in?vivo study on the effect of antifungal agents on hematopoietic cells in mice

Liposomal amphotericin B, voriconazole, and caspofungin are currently used for systemic and severe fungal infections. Patients with malignant diseases are treated with granulocyte-colony stimulating factor (G-CSF) for the recovery of granulocytes after chemotherapy or hematopoietic cell (HC) transplantation. Since they have a high incidence of fungal infections, they inevitably receive antifungal drugs for treatment and prophylaxis. Despite their proven less toxicity for various cell types comparatively with amphotericin B and the decrease in the number of leukocytes that has been reported as a possible complication in clinical studies, the effect of liposomal amphotericin B, voriconazole, and caspofungin on HCs has not been clarified. The present study aimed to examine the in vitro and in vivo effect of these three modern antifungals on HCs. Colony-forming unit (CFU) assays of murine bone marrow cells were performed in methylcellulose medium with or without cytokines and in the presence or absence of various concentrations of liposomal amphotericin B, voriconazole, and caspofungin. In the in vivo experiments, the absolute number of granulocytes was determined during leukocyte recovery in sublethally irradiated mice receiving each antifungal agent separately, with or without G-CSF. In vitro, all three antifungal drugs were nontoxic and, interestingly, they significantly increased the number of CFU-granulocyte-macrophage colonies in the presence of cytokines, at all concentrations tested. This was contrary to the concentration-dependent toxicity and the significant decrease caused by conventional amphotericin B. In vivo, the number of granulocytes was significantly higher with caspofungin plus G-CSF treatment, higher and to a lesser extent higher, but not statistically significantly, with voriconazole plus G-CSF and liposomal amphotericin B plus G-CSF treatments, respectively, as compared with G-CSF alone. These data indicate a potential synergistic effect of these antifungals with the cytokines, in vitro and in vivo, with subsequent positive effect on hematopoiesis.     

Current Epidemiology and Management of Invasive Candidiasis in Infants

Invasive candidiasis (IC) is common in premature infants and is associated with significant morbidity and mortality. Although the incidence of IC in infants is decreasing, there is marked variability in number of cases by center and geographical region, and current methods for diagnosis are suboptimal. Nonabsorbable antifungals, probiotics, and systemic antifungals have been shown to decrease IC in select populations. Although empirical antifungal therapy may provide benefit to infants with IC, prediction of the disease is difficult. While available antifungal agents appear to be effective in the treatment of IC in infants, knowledge of the optimal type, dose, and duration of antifungal therapy is limited by the low number of available infant studies.