A randomized, blinded, multicenter trial of lipid-associated amphotericin B alone versus in combination with an antibody-based inhibitor of heat shock protein 90 in patients with invasive candidiasis

Echinocandin Resistance in Candida Species: Mechanisms of Reduced Susceptibility and Therapeutic Approaches

OBJECTIVE:

To summarize published data regarding mechanisms of reduced echinocandin susceptibility in Candida spp., the impact of echinocandin resistance on the fitness and virulence of Candida isolates, and current and future treatment approaches.

DATA SOURCES:

A search of MEDLINE databases (1966-September 2011) was conducted.

STUDY SELECTION AND DATA EXTRACTION:

Databases were searched using the terms echinocandin, resistance, and Candida. Citations from publications were reviewed for additional references.

DATA SYNTHESIS:

Echinocandins have in vitro activity against most Candida spp. and are first-line agents in the treatment of candidemia. However, case reports describing echinocandin treatment failure due to resistant isolates have been published. Reduced echinocandin susceptibility has been shown to occur via 3 main mechanisms: (1) adaptive stress responses, which result in elevated cell wall chitin content and paradoxical growth in vitro at supra minimum inhibitory concentrations (MICs); (2) acquired FKS mutations, which confer reduced glucan synthase sensitivity, elevated MICs, and are associated with clinical failure; and (3) intrinsic FKS mutations, which are naturally occurring mutations in C. parapsilosis and C. guilliermondii, which confer elevated MIC levels but a lower level of reduced glucan synthase sensitivity compared with acquired FKS mutations. Some FKS mutants have been shown to have significantly reduced fitness and virulence versus wild type isolates and may contribute to the low incidence of echinocandin resistance reported in large surveillance studies. Treatment strategies evaluated for FKS mutants include echinocandin dose escalation and combination with agents such as calcineurin inhibitors, HSP90 inhibitors, and chitin synthase inhibitors.

CONCLUSIONS:

While the incidence of echinocandin resistance in Candida spp. is low, it can present a significant therapeutic challenge, especially in multidrug-resistant Candida isolates. Dose escalation is unlikely to be effective in treating FKS mutant isolates, and significant adverse effects limit the clinical use of agents evaluated as combination therapy. Patients with infections failing to respond to echinocandin therapy should undergo susceptibility testing and be treated with an alternative antifungal agent if possible.

Towards a universal disulphide stabilised single chain Fv format: importance of interchain disulphide bond location and vL-vH orientation

Engineered introduction of interface interchain disulphide bonds is perceived to be a simple method to increase the stability of single chain Fv (scFv). Six disulphide bond locations have been cited within the literature but the potential for the broad use of each has not been examined. Five of these disulphide bond locations were introduced into one scFv in order to compare their relative effects on expression, thermal stability, percent monomer formation and retention of antigen binding. The disulphide bond position vH44-vL100 was observed to enable the most favourable balance of biophysical properties. The vH44-vL100 disulphide bond was introduced into five additional scFv in both vL-vH and vH-vL orientations in order to investigate its general applicability. Data are presented to show the relative influence of scFv sequence, v-region organisation and interchain disulphide bond on expression yield, thermal stability and percent monomer. Introduction of the vH44-vL100 disulphide bond typically resulted in no or little increase in thermal stability and no change in percent monomer but did confer the benefit of permanently fixing monomer:dimer ratios during purification and analysis.

In vitro and in vivo role of heat shock protein 90 in Amphotericin B resistance of Aspergillus terreus

Aspergillus terreus (A. terreus) is of serious concern because of a high propensity to dissemination and in vitro and in vivo resistance to Amphotericin B (AmB). The underlying molecular mechanism of AmB is not known yet and here we want to explore whether fungal heat shock protein 90 (HSP90) is involved in polyene resistance in A. terreus. AmB-susceptible (ATS) and AmB-resistant (ATR) A. terreus and AmB-susceptible Aspergillus fumigatus (AFS) were investigated in response to AmB with a special focus on HSP90. HSP90 inhibitors resulted in significant improvement of AmB activity against ATR as minimum inhibitory concentrations (MIC) decreased from 32 to 0.38 mg/L. Gene expression profiling showed a greater basal amount of HSP90 levels in ATR and ATS when compared with AFS. HSP90 blockers in combination with AmB were evaluated in a murine model of disseminated aspergillosis. HSP90 inhibitors were not beneficial for mice infected with ATR, and neither mono- nor combination treatment with AmB yielded clinical improvement. HSP90 inhibition with 17-allylamino-17-demethoxygeldanamycin (17-AAG) was harmful. HSP90 seems to play a vital role in antifungal stress response in all aspergilli tested, whereas HSP90 does not substantiate the origin of AmB resistance in ATR.

Nonspecific effect of Mycograb on amphotericin B MIC

Mycograb C28Y is a recombinant human antibody fragment thought to target HSP-90 and potentiate amphotericin B (AMB). Absence of in vivo efficacy led us to reevaluate its in vitro activity. Interactions between AMB and Mycograb were investigated using a checkerboard design. Addition of Mycograb or various unrelated proteins, including human serum, resulted in similar decreases in the MIC of AMB. Potentiation of AMB by Mycograb appears to be a nonspecific protein effect.

[Antifungal therapy update: new drugs and medical uses]

Increases in the rates of fungal infections, as well as their associated morbidity and mortality has led to a need for additional antifungal agents. The most common serious fungal agents in immunosuppressed and critically ill patients are Candida spp. and Aspergillus spp., although other emerging fungi must be considered. Rational, early systemic antifungal treatment should be based on diagnostic imaging techniques and conventional mycological and non-culture-based procedures. While the availability of new therapeutic options is an important advance, antifungal therapy has become increasingly complex. In addition to the available antifungal armamentarium, recent research has resulted in the introduction of three new antifungal agents: micafungin, anidulafungin, and posaconazole. This article provides an update, based on the latest scientific evidence, of the clinical efficacy, pharmacokinetics, safety and dosing of antifungal drugs administered in the management of Candida spp., Aspergillus spp., Cryptococcus spp., Zygomycetes, Scedosporium spp. and Fusarium spp.

European expert opinion on the management of invasive candidiasis in adults

This report discusses the present status of antifungal therapy and treatment options for candidaemia, considered by experts in the field in Europe. A conference of 26 experts from 13 European countries was held to discuss strategies for the treatment and prevention of invasive candidiasis, with the aim of providing a review on optimal management strategies. Published and unpublished comparative trials on antifungal therapy were analysed and discussed. Commonly asked questions about the management of candidaemia were selected, and possible responses to these questions were discussed. Panellists were then asked to respond to each question by using a touchpad answering system. After the initial conference, the viewpoint document has been reviewed and edited to include new insights and developments since the initial meeting. For many situations, consensus on treatment could not be reached, and the responses indicate that treatment is likely to be modified on a patient-to-patient basis, depending on factors such as degree of illness, prior exposure to azole antifungals, and the presence of potentially antifungal drug-resistant Candida species.

Progress toward a Staphylococcus aureus vaccine

High attack rates and the ability of Staphylococcus aureus to develop resistance to all antibiotics in medical practice heightens the urgency for vaccine development. S. aureus causes many disease syndromes, including invasive disease, pneumonia, and skin and soft tissue infections. It remains unclear whether a single vaccine could protect against all of these. Vaccine composition is also challenging. Active immunization with conjugated types 5 and 8 capsular polysaccharides, an iron scavenging protein, isdB, and passive immunization against clumping factor A and lipoteichoic acid have all proven unsuccessful in clinical trials. Many experts advocate an approach using multiple antigens and have suggested that the right combination of antigens has not yet been identified. Others advocate that a successful vaccine will require antigens that work by multiple immunologic mechanisms. Targeting staphylococcal protein A and stimulating the T-helper 17 lymphocyte pathway have each received recent attention as alternative approaches to vaccination in addition to the more traditional identification of opsonophagocytic antibodies. Many questions remain as to how to successfully formulate a successful vaccine and to whom it should be deployed.

Antifungal resistance and new strategies to control fungal infections

Despite improvement of antifungal therapies over the last 30 years, the phenomenon of antifungal resistance is still of major concern in clinical practice. In the last 10 years the molecular mechanisms underlying this phenomenon were extensively unraveled. In this paper, after a brief overview of currently available antifungals, molecular mechanisms of antifungal resistance will be detailed. It appears that major mechanisms of resistance are essential due to the deregulation of antifungal resistance effector genes. This deregulation is a consequence of point mutations occurring in transcriptional regulators of these effector genes. Resistance can also follow the emergence of point mutations directly in the genes coding antifungal targets. In addition we further describe new strategies currently undertaken to discover alternative therapy targets and antifungals. Identification of new antifungals is essentially achieved by the screening of natural or synthetic chemical compound collections. Discovery of new putative antifungal targets is performed through genome-wide approaches for a better understanding of the human pathogenic fungi biology.

Development of a vaccine against Staphylococcus aureus

A vaccine to prevent infections caused by Staphylococcus aureus would have a tremendously beneficial impact on public health. In contrast to typical encapsulated bacterial pathogens, such as Streptococcus pneumoniae, H. influenzae, and Neisseria meningitides, the capsule of S. aureus is not clearly linked to strain virulence in vivo. Furthermore, it is not clear that natural infection caused by S. aureus induces a protective humoral immune response, as does infection caused by typical encapsulated bacteria. Finally, pure B cell or antibody deficiency, in either animal models or in patients, does not predispose to more frequent or more severe S. aureus infections, as it does for infections caused by typical encapsulated bacteria. Rather, primary immune mechanisms necessary for protection against S. aureus infections include professional phagocytes and T lymphocytes (Th17 cells, in particular) which upregulate phagocytic activity. Thus, it is not clear whether an antibody-mediated neutralization of S. aureus virulence factors should be the goal of vaccination. Rather, the selection of antigenic targets which induce potent T cell immune responses that react to the broadest possible array of S. aureus strains should be the focus of antigen selection. Of particular promise is the potential to select antigens which induce both humoral and T cell-mediated immunity in order to generate immune synergy against S. aureus infections. A single-antigen vaccine may achieve this immune synergy. However, multivalent antigens may be more likely to induce both humoral and T cell immunity and to induce protection against a broader array of S. aureus isolates. A number of candidate vaccines are in development, raising the promise that effective vaccines against S. aureus will become available in the not-so-distant future. Possible development programs for such vaccines are discussed.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.

Vaccine and monoclonal antibody that enhance mouse resistance to candidiasis

Previously we showed that antibodies specific for the glycan β-1,2-mannotriose [β-(Man)(3)] on the cell surface of Candida albicans protect mice against disseminated candidiasis (H. Xin, S. Dziadek, D. R. Bundle, and J. E. Cutler, Proc. Natl. Acad. Sci. U. S. A. 105:13526-13531, 2008). Furthermore, six 14-mer peptides that are within the N-terminal portion of C. albicans wall proteins were conjugated to the glycan in an attempt to create immunogenic glycopeptide conjugates. By a dendritic cell (DC)-based immunization approach, all were immunogenic and three of the six conjugates induced a high degree of protection in mice. Interestingly, whereas all six peptides induced antibody responses when used alone to pulse DCs for subsequent immunizations, three peptides induced protection, and one in particular, peptide Fba (derived from fructose-bisphosphate aldolase), induced robust protective responses and is the focus of the current work. Fba peptide is not restricted by the major histocompatibility complex class II (MHC-II), as it induced anti-Fba antibodies in mice of different H-2 haplotypes and in rabbits. Furthermore, the peptide induced protection against disease caused by different C. albicans strains. Partial protection was achieved when alum was used in place of DCs for Fba immunizations. The passive transfer of immune sera from Fba-vaccinated mice, but not immune serum preabsorbed with fungal cells, conferred protection in naïve mice. This result, along with our finding that a monoclonal antibody specific for the peptide, E2-9 (IgM), protected mice against candidiasis, provide strong evidence that antibodies contribute to protection. Our work demonstrates the utility of cell wall peptides alone or as glycopeptides in vaccines designed for the induction of immunity against candidiasis and monoclonal antibodies as a rapid immunoprotective approach against the disease.

New concepts in the pathogenesis, diagnosis and treatment of bacteremia and sepsis

Bacteremia and sepsis are major health concerns. Despite intensive research, there are only a limited number of successful treatment options, and it is difficult to see the forest for the trees when considering the pathogenesis of this condition. Studies in the last decade have shown that a major pathophysiologic event in sepsis is the progression from proinflammation to an immunosuppressive state. However, recent genome-based data indicate that sepsis-related inflammatory responses are highly variable, which calls in question the classic two-phase model of sepsis. Adequate and timely antimicrobial treatment is a cornerstone for survival in patients with bacteremia and sepsis. However, microbial resistance has emerged as an increasing challenge for clinicians and with an increasing number of resistant pathogens causing infections, selection of empiric antimicrobial treatment has become difficult. Treatment options currently under way are targeted to enhance immune responses, rebalance the regulation of the dysregulated immune system, remove endotoxin and block/inhibit apoptosis.

T cell immunity and vaccines against invasive fungal diseases

Over the past two decades much has been learned about the immunology of invasive fungal infection, especially invasive candidiasis and invasive aspergillosis. Although quite different in their pathogenesis, the major common protective host response is Th1 mediated. It is through Th1 cytokine production that the effector cells, phagocytes, are activated to kill the fungus. A more thorough understanding of the pathogenesis of disease, the elicited protective Th1 immune response, the T cell antigen(s) which elicit this response, and the mechanism(s) whereby one can enhance, reconstitute, or circumvent the immunosuppressed state will, hopefully, lead to the development of a vaccine(s) capable of protecting even the most immunocompromised of hosts.

The anti-proliferative effect of heat shock protein 90 inhibitor, 17-DMAG, on non-small-cell lung cancers being resistant to EGFR tyrosine kinase inhibitor

Acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), gefitinib and erlotinib, is frequently observed after initiation of TKIs therapy. Non-small-cell lung cancers (NSCLC) with activating EGFR mutations were reported to be sensitive to heat shock protein 90 (Hsp90) inhibitors regardless of the secondary TKI-resistant T790M mutation. We established EGFR-TKI resistant clones for PC-9 cell lines, harboring EGFR exon 19 deletions, with or without the secondary T790M mutation. We examined the anti-proliferative effect of 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), an orally active Hsp90 inhibitor, on the growth of NSCLC cell lines in vitro and in vivo. In MTS assay, the IC(50) values of 17-DMAG for 13 EGFR-mutant cell lines including eight EGFR-TKI resistant cell lines ranged from 0.04 to 0.16 μM while those for seven EGFR-wild type cell lines ranged from 1.6 to 27.4 μM. Western blot analysis revealed that phospho-EGFR, phospho-Akt, phospho-MAPK, cdk4, and cyclin D1 were more readily depleted by 17-DMAG treatment in EGFR-mutant cell lines than in EGFR-wild type cell lines. Cleaved PARP expression confirmed apoptosis in response to 17-DMAG treatment in EGFR-mutant cell lines but not in EGFR-wild type cell lines. In mice xenograft models, 17-DMAG significantly reduced the growth of EGFR-mutant lines irrespective of T790M mutation. These results suggested that 17-DMAG is a potential novel therapeutic agent for NSCLC patients with EGFR mutations with or without EGFR-TKI resistance.

Direct effects of non-antifungal agents used in cancer chemotherapy and organ transplantation on the development and virulence of Candida and Aspergillus species

Conventional antineoplastic, novel immunosuppressive agents and antibiotics used in cancer treatment can directly affect the growth, development and virulence of Candida and Aspergillus species. Cytotoxic and cisplatin compounds have anti-Candida activity and may be synergistic with antifungal drugs; they also inhibit Candida and Aspergillus filamentation/conidation and effect increased virulence in vitro. Glucocorticoids enhance Candida adherence to epithelial cells, germination in serum and in vitro secretion of phospholipases and proteases, as well as growth of A. fumigatus. Calcineurin and target of rapamycin inhibitors perturb Candida and Aspergillus morphogenesis, stress responses and survival in serum, reduce azole tolerance in Candida, but yield conflicting in vivo data. Inhibition of candidal heat shock protein 90 and candidal-specific histone deacetylase represent feasible therapeutic approaches for candidiasis. Tyrosine kinase inhibitors inhibit fungal cell entry into epithelial cells and phagocytosis. Quinolone and other antibiotics may augment activity of azole and polyene agents. The correlation of in vitro effects with clinically meaningful in vivo systems is warranted. 

[Update: invasive fungal infections: Diagnosis and treatment in surgical intensive care medicine]

Fungal infections are of great relevance in surgical intensive care and Candida species represent the predominant part of fungal pathogens. Invasive aspergillosis is also relevant especially in patients with chronic pulmonary diseases. It is crucial for therapy success to begin adequate antifungal treatment at an early stage of the disease. Risk stratification of individual patient symptoms is essential for therapy timing. In case of suspected or proven candida infection, fluconazole is the agent of choice when the patient is clinically stable and no azoles have been administrated in advance and the local epidemiology makes azol resistance unlikely. For clinically instable patients with organ dysfunction the echinocandins serve as primary therapy because of their broad spectrum and reasonable safety profile. Due to a relevant proportion of azole resistant Candida species, susceptibility testing should be done routinely. Depending on the species detected de-escalating to an azole is feasible if organ dysfunctions have resolved. An invasive aspergillosis is primarily treated with voriconazole.

Regulatory circuitry governing fungal development, drug resistance, and disease

Pathogenic fungi have become a leading cause of human mortality due to the increasing frequency of fungal infections in immunocompromised populations and the limited armamentarium of clinically useful antifungal drugs. Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus are the leading causes of opportunistic fungal infections. In these diverse pathogenic fungi, complex signal transduction cascades are critical for sensing environmental changes and mediating appropriate cellular responses. For C. albicans, several environmental cues regulate a morphogenetic switch from yeast to filamentous growth, a reversible transition important for virulence. Many of the signaling cascades regulating morphogenesis are also required for cells to adapt and survive the cellular stresses imposed by antifungal drugs. Many of these signaling networks are conserved in C. neoformans and A. fumigatus, which undergo distinct morphogenetic programs during specific phases of their life cycles. Furthermore, the key mechanisms of fungal drug resistance, including alterations of the drug target, overexpression of drug efflux transporters, and alteration of cellular stress responses, are conserved between these species. This review focuses on the circuitry regulating fungal morphogenesis and drug resistance and the impact of these pathways on virulence. Although the three human-pathogenic fungi highlighted in this review are those most frequently encountered in the clinic, they represent a minute fraction of fungal diversity. Exploration of the conservation and divergence of core signal transduction pathways across C. albicans, C. neoformans, and A. fumigatus provides a foundation for the study of a broader diversity of pathogenic fungi and a platform for the development of new therapeutic strategies for fungal disease.

Fungicidal monoclonal antibody C7 interferes with iron acquisition in Candida albicans

We have developed a monoclonal antibody (MAb), C7, that reacts with the Als3p and enolase present in the Candida albicans cell wall and exerts three anti-Candida activities: candidacidal activity and inhibition of both adhesion and filamentation. To investigate the mode of action of MAb C7 on fungal viability, we examined changes in the genome-wide gene expression profile of C. albicans grown in the presence of a subinhibitory concentration of MAb C7 (12.5 μg/ml) by using microarrays. A total of 49 genes were found to be differentially expressed upon treatment with MAb C7. Of these, 28 were found to be upregulated and 21 were found to be downregulated. The categories of upregulated genes with the largest number of variations were those involved in iron uptake or related to iron homeostasis (42.86%), while the energy-related group accounted for 38.10% of the downregulated genes (8/21). Results were validated by real-time PCR. Since these effects resembled those found under iron-limited conditions, the activity of MAb C7 on C. albicans mutants with deletions in key genes implicated in the three iron acquisition systems described in this yeast was also assessed. Only mutants lacking the TPK1 gene and, to a lesser extent, the TPK2 gene were less sensitive to the candidacidal effect of MAb C7. FeCl(3) or hemin at concentrations of ≥ 7.8 μM reversed the candidacidal effect of MAb C7 on C. albicans in a concentration-dependent manner. The results presented in this study provide evidence that the candidacidal effect of MAb C7 is related to the blockage of the reductive iron uptake pathway of C. albicans.

Dose range evaluation of Mycograb C28Y variant, a human recombinant antibody fragment to heat shock protein 90, in combination with amphotericin B-desoxycholate for treatment of murine systemic candidiasis

Systemic candidiasis causes significant mortality in patients despite amphotericin B (AMB) therapy. Mycograb C28Y variant, a human recombinant antibody fragment to heat shock protein 90, is closely related to Mycograb, which showed a survival advantage in combination with AMB in a phase III human trial. The Mycograb C28Y variant could potentially increase the antifungal effect of AMB. In our study, the interaction between AMB-desoxycholate (DAMB) and the Mycograb C28Y variant was characterized in vitro by using a checkerboard method. Quantitative cultures of kidneys, livers, and spleens of neutropenic mice with systemic Candida albicans infections were used to assess the in vivo interaction between 1.4 mg/kg of body weight/day of DAMB and 0.15, 1.5, and 15 mg/kg/day of the Mycograb C28Y variant after 1, 3, and 5 days of therapy. DAMB and Mycograb C28Y variant monotherapies, vehicle, and a no-treatment arm served as controls. Also, single- and multidose pharmacokinetics for the Mycograb C28Y variant were determined. Indifference or synergy between DAMB and the Mycograb C28Y variant was seen in two trials by the checkerboard method. The pharmacokinetics of the Mycograb C28Y variant was best described by a 2-compartment model with a median serum t(1/2)(α) of ~0.198 h and a t(1/2)(β) of ~1.77 h. In mice, DAMB together with the Mycograb C28Y variant was no more effective than AMB alone (P > 0.05 by analysis of variance). The Mycograb C28Y variant alone had no antifungal activity. We therefore conclude that the Mycograb C28Y variant in combination with DAMB offered no benefit over DAMB monotherapy in a neutropenic murine model of systemic candidiasis.

Antifungal prophylaxis and therapy in patients with hematological malignancies and hematopoietic stem cell transplant recipients

Patients with acute leukemia and hematopoietic stem cell transplant recipients are at risk of a spectrum of invasive fungal diseases corresponding to the type and intensity of immunosuppression. The development of newer antifungal agents has broadened therapeutic options. In the 1990s, lipid formulations of amphotericin B became widely used as safer alternatives to amphotericin B deoxycholate. In addition, fluconazole was shown to be beneficial as a yeast-active prophylaxis in hematopoietic stem cell transplant recipients. In the past decade, the antifungal armamentarium was further enhanced with the availability of extended-spectrum azoles and echinocandins. The development of effective broad-spectrum antifungal agents has led to their use as prophylaxis rather than delaying treatment until clinical signs of infection manifest. Antigen-based and PCR-based diagnostic adjuncts facilitate earlier detection of invasive fungal diseases compared with conventional culture, and have been incorporated into strategies in which initiation or modification of an antifungal regimen is targeted to patients with the highest likelihood of having fungal disease. Here, we review the pharmacological data and major clinical trials that guide the use of antifungals, as well as areas of uncertainty and future perspectives.

Clinical factors associated with a Candida albicans Germ Tube Antibody positive test in Intensive Care Unit patients

BACKGROUND

Poor outcomes of invasive candidiasis (IC) are associated with the difficulty in establishing the microbiological diagnosis at an early stage. New scores and laboratory tests have been developed in order to make an early therapeutic intervention in an attempt to reduce the high mortality associated with invasive fungal infections. Candida albicans IFA IgG has been recently commercialized for germ tube antibody detection (CAGTA). This test provides a rapid and simple diagnosis of IC (84.4% sensitivity and 94.7% specificity). The aim of this study is to identify the patients who could be benefited by the use of CAGTA test in critical care setting.

METHODS

A prospective, cohort, observational multicentre study was carried out in six medical/surgical Intensive care units (ICU) of tertiary-care Spanish hospitals. Candida albicans Germ Tube Antibody test was performed twice a week if predetermined risk factors were present, and serologically demonstrated candidiasis was considered if the testing serum dilution was ≥ 1:160 in at least one sample and no other microbiological evidence of invasive candidiasis was found.

RESULTS

Fifty-three critically ill non-neutropenic patients (37.7% post surgery) were included. Twenty-two patients (41.5%) had CAGTA-positive results, none of them with positive blood culture for Candida. Neither corrected colonization index nor antifungal treatment had influence on CAGTA results. This finding could corroborate that the CAGTA may be an important biomarker to distinguish between colonization and infection in these patients. The presence of acute renal failure at the beginning of the study was more frequent in CAGTA-negative patients. Previous surgery was statistically more frequent in CAGTA-positive patients.

CONCLUSIONS

This study identified previous surgery as the principal clinical factor associated with CAGTA-positive results and emphasises the utility of this promising technique, which was not influenced by high Candida colonization or antifungal treatment. Our results suggest that detection of CAGTA may be important for the diagnosis of invasive candidiasis in surgical patients admitted in ICU.

Novel strategies for the prevention and treatment of Candida infections: the potential of immunotherapy

Infections caused by Candida spp. continue to be a substantial cause of disease burden, especially in immunocompromised patients. New approaches are needed to improve the outcome of patients suffering from Candida infections, because it seems unlikely that the established standard treatment will drastically lower the morbidity of mucocutaneous Candida infections and the high mortality associated with invasive candidiasis. New insights into the mechanisms of the anti-Candida host response have contributed to the design of novel immunotherapeutic approaches that have been proposed as adjuvant therapy in Candida infections. This review presents an overview of novel strategies in the prevention and treatment of Candida infections, with a special focus on adjuvant immunotherapy.

Metallochelating liposomes with associated lipophilised norAbuMDP as biocompatible platform for construction of vaccines with recombinant His-tagged antigens: preparation, structural study and immune response towards rHsp90

Hsp90-CA is present in cell wall of Candida pseudohyphae or hyphae-typical pathogenic morphotype for both systemic and mucosal Candida infections. Heat shock protein from Candida albicans (hsp90-CA) is an important target for protective antibodies during disseminated candidiasis of experimental mice and human. His-tagged protein rHsp90 was prepared and used as the antigen for preparation of experimental recombinant liposomal vaccine. Nickel-chelating liposomes (the size around 100nm, PDI≤0.1) were prepared from the mixture of egg phosphatidyl choline and nickel-chelating lipid DOGS-NTA-Ni (molar ratio 95:5%) by hydration of lipid film and extrusion methods. New non-pyrogenic hydrophobised derivative of MDP (C18-O-6-norAbuMDP) was incorporated into liposomes as adjuvans. rHsp90 was attached onto the surface of metallochelating liposomes by metallochelating bond and the structure of these proteoliposomes was studied by dynamic light scattering, AF microscopy, TEM and GPC. The liposomes with surface-exposed C18-O-6-norAbuMDP were well recognised and phagocyted by human dendritic cells in vitro. In vivo the immune response towards this experimental vaccine applied in mice (i.d.) demonstrated both TH1 and TH2 response comparable to FCA, but without any side effects. Metallochelating liposomes with lipophilic derivatives of muramyl dipeptide represent a new biocompatible platform for construction of experimental recombinant vaccines and drug-targeting systems.

Potential of anti-Candida antibodies in immunoprophylaxis

The need for new options for the treatment of invasive candidiasis has fuelled the use of antibodies in combination with conventional antifungal therapy. After a long period of time in which antibodies were considered irrelevant in the resistance against invasive candidiasis, it was demonstrated that a number of antibodies or their engineered derivatives directed against Candida albicans cell-wall polysaccharides and glycopeptides, as well as against some protein epitopes, confer protection against invasive candidiasis. This has confirmed this approach as a new strategy for the prophylaxis of invasive candidiasis. Of particular interest is Mycograb, a human recombinant monoclonal antibody that inhibits heat shock protein 90, and has been administrated in combination with lipid-associated amphotericin B to patients with invasive candidiasis, and the fungicidal anti-beta-glucan antibodies induced by the glycoconjugate vaccine composed of a beta-glucan polysaccharide conjugated with the diphtheria toxoid CRM 197. However, despite the promising data obtained in vitro and in animal models, at present there is very little clinical experience on the use of antibodies in Candida immunoprophylaxis.

Opportunistic fungi: a view to the future

Opportunistic fungi are a constantly evolving group of pathogens that plague a growing group of vulnerable patients. These include hospitalized patients, especially those in the intensive care unit; stem cell and solid organ transplant recipients; patients treated with immunosuppressant medications; those with advanced human immunodeficiency virus or other acquired immunodeficiency conditions; and patients with organ failure syndromes. Rapid diagnosis of invasive fungal infection is essential to optimize outcomes. Several newer nonculture-based diagnostics, including the Aspergillus galactomannan enzyme-linked immunosorbent assay, the beta-d-glucan assay and the multiplex polymerase chain reaction-based assays, may emerge as important tools facilitating early intervention with effective antifungal therapy. Newer azoles, including posaconazole, isavuconazole and ravuconazole, will potentially provide more effective therapeutic options in the future, diminishing the role for amphotericin B.

Prediction of the clinical outcome in invasive candidiasis patients based on molecular fingerprints of five anti-Candida antibodies in serum

Better prognostic predictors for invasive candidiasis (IC) are needed to tailor and individualize therapeutic decision-making and minimize its high morbidity and mortality. We investigated whether molecular profiling of IgG-antibody response to the whole soluble Candida proteome could reveal a prognostic signature that may serve to devise a clinical-outcome prediction model for IC and contribute to known IC prognostic factors. By serological proteome analysis and data-mining procedures, serum 31-IgG antibody-reactivity patterns were examined in 45 IC patients randomly split into training and test sets. Within the training cohort, unsupervised two-way hierarchical clustering and principal-component analyses segregated IC patients into two antibody-reactivity subgroups with distinct prognoses that were unbiased by traditional IC prognostic factors and other patients-related variables. Supervised discriminant analysis with leave-one-out cross-validation identified a five-IgG antibody-reactivity signature as the most simplified and accurate IC clinical-outcome predictor, from which an IC prognosis score (ICPS) was derived. Its robustness was confirmed in the test set. Multivariate logistic-regression and receiver-operating-characteristic curve analyses demonstrated that the ICPS was able to accurately discriminate IC patients at high risk for death from those at low risk and outperformed conventional IC prognostic factors. Further validation of the five-IgG antibody-reactivity signature on a multiplexed immunoassay supported the serological proteome analysis results. The five IgG antibodies incorporated in the ICPS made biologic sense and were associated either with good-prognosis and protective patterns (those to Met6p, Hsp90p, and Pgk1p, putative Candida virulence factors and antiapoptotic mediators) or with poor-prognosis and risk patterns (those to Ssb1p and Gap1p/Tdh3p, potential Candida proapoptotic mediators). We conclude that the ICPS, with additional refinement in future larger prospective cohorts, could be applicable to reliably predict patient clinical-outcome for individualized therapy of IC. Our data further provide insights into molecular mechanisms that may influence clinical outcome in IC and uncover potential targets for vaccine design and immunotherapy against IC.

An insight into the antifungal pipeline: selected new molecules and beyond

Invasive fungal infections are increasing in incidence and are associated with substantial mortality. Improved diagnostics and the availability of new antifungals have revolutionized the field of medical mycology in the past decades. This Review focuses on recent developments in the antifungal pipeline, concentrating on promising candidates such as new azoles, polyenes and echinocandins, as well as agents such as nikkomycin Z and the sordarins. Developments in vaccines and antibody-based immunotherapy are also discussed. Few therapeutic products are currently in active development, and progression of therapeutic agents with fungus-specific mechanisms of action is of key importance.

[Spanish Paediatric Infectious Diseases Society consensus document on the treatment of fungal infections based on the immune response]

Despite the emergence of new diagnostic and therapeutic methods, invasive fungal infections are still a major cause of morbidity and mortality in immunocompromised and critical patients. Therefore, adjuvant treatments to the standard antifungal therapy are being investigated, with immunity-based therapy being one of the most important. Both immunomodulatory (dendritic and T cells transfusions, colony stimulating factors, interferón-gamma, interleukin 12, fungal vaccines, transfer factors and certain drugs such as chloroquine) and immunotherapeutic modalities (granulocyte transfusions, monoclonal antibodies and intravenous immunoglobulin) have been described. This document aims to summarise currently available data on immunity-based therapy of fungal infections and to provide basic knowledge on the immune response to fungal infections. This helps to understand how, in selected cases, immunity-based therapy may improve the response to standard antifungal treatment. The potential indications of immunity-based therapy in the paediatric patient are reviewed, although there is still a lack of scientific evidence for its use in children.

Systematic review and meta-analysis of the tolerability and hepatotoxicity of antifungals in empirical and definitive therapy for invasive fungal infection

To evaluate the tolerability and liver safety profiles of the systemic antifungal agents commonly used for the treatment of invasive fungal infection, we conducted a systematic review and meta-analysis of randomized controlled trials published before 31 August 2009. Two reviewers independently applied selection criteria, performed quality assessment, and extracted data. We used the beta-binomial model to account for variation across studies and the maximum likelihood method to estimate the pooled risks. We identified 39 studies with more than 8,000 enrolled patients for planned comparisons. The incidence rates of treatment discontinuation due to adverse reactions and liver injury associated with antifungal therapy ranged widely. The pooled risks of treatment discontinuation due to adverse reactions were above 10% for amphotericin B formulations and itraconazole, whereas they were 2.5% to 3.8% for fluconazole, caspofungin, and micafungin. We found that 1.5% of the patients stopped itraconazole treatment due to hepatotoxicity. Furthermore, 19.7% of voriconazole users and 17.4% of itraconazole users had elevated serum liver enzyme levels, although they did not require treatment discontinuation, whereas 2.0% or 9.3% of fluconazole and echinocandin users had elevated serum liver enzyme levels but did not require treatment discontinuation. The results were similar when we stratified the data by empirical or definitive antifungal therapy. Possible explanations for antifungal agent-related hepatotoxicity were confounded by antifungal prescription to patients with a high risk of liver injury, the increased chance of detection of hepatotoxicity due to prolonged treatment, or the pharmacological entity.

Candidemia and invasive candidiasis: a review of the literature for the burns surgeon

Advances in critical care, operative techniques, early fluid resuscitation, antimicrobials to control bacterial infections, nutritional support to manage the hypermetabolic response and early wound excision and coverage has improved survival rates in major burns patients. These advances in management have been associated with increased recognition of invasive infections caused by Candida species in critically ill burns patients. Candida albicans is the most common species to cause invasive Candida infections, however, non-albicans Candida species appear to becoming more frequent. These later species may be less fluconazole susceptible than Candida albicans. High crude and attributable mortality rates from invasive Candida sepsis are multi-factorial. Diagnosis of invasive candidiasis and candidemia remains difficult. Prophylactic and pre-emptive therapies appear promising strategies, but there is no specific approach which is well-studied and clearly efficacious in high-risk burns patients. Treatment options for invasive candidiasis include several amphotericin B formulations and newer less toxic antifungal agents, such as azoles and echinocandins. We review the currently available data on diagnostic and management strategies for invasive candidiasis and candidemia; whenever possible providing reference to the high-risk burn patients. We also present an algorithm for the management of candidemia and invasive candidiasis in burn patients.

Serological profiling of a Candida albicans protein microarray reveals permanent host-pathogen interplay and stage-specific responses during candidemia

Candida albicans in the immunocompetent host is a benign member of the human microbiota. Though, when host physiology is disrupted, this commensal-host interaction can degenerate and lead to an opportunistic infection. Relatively little is known regarding the dynamics of C. albicans colonization and pathogenesis. We developed a C. albicans cell surface protein microarray to profile the immunoglobulin G response during commensal colonization and candidemia. The antibody response from the sera of patients with candidemia and our negative control groups indicate that the immunocompetent host exists in permanent host-pathogen interplay with commensal C. albicans. This report also identifies cell surface antigens that are specific to different phases (i.e. acute, early and mid convalescence) of candidemia. We identified a set of thirteen cell surface antigens capable of distinguishing acute candidemia from healthy individuals and uninfected hospital patients with commensal colonization. Interestingly, a large proportion of these cell surface antigens are involved in either oxidative stress or drug resistance. In addition, we identified 33 antigenic proteins that are enriched in convalescent sera of the candidemia patients. Intriguingly, we found within this subset an increase in antigens associated with heme-associated iron acquisition. These findings have important implications for the mechanisms of C. albicans colonization as well as the development of systemic infection.

Candida albicans has both a benign and pathogenic association with the human host. Previous to this study, little was known in regard to how the host humoral system responds to the commensal colonization of C. albicans, as well as the development of hematogenously disseminated candidiasis. We show using a C. albicans cell surface protein microarray that the immunocompetent host exists in permanent host-pathogen interplay with commensal C. albicans, and undergoes stage-specific antibody responses as the yeast transitions from a benign microbe to an opportunistic fungal pathogen. Also identified were serological signatures specific for acute and convalescent stages of candidemia. Our findings provide new insight in the characterization of potential serodiagnostic antigens and vaccine candidates to the opportunistic pathogen C. albicans.

Pathogen-specific antibodies: codependent no longer

Antibody-mediated defense against pathogens typically requires complex interactions between antibodies and other constituents of the humoral and cellular immune systems. However, recent evidence indicates that some antibodies alone can inhibit pathogen function in the absence of complement, phagocytes, or NK cells. In this issue of the JCI, McClelland et al. have begun to elucidate the molecular bases by which antibodies alone can impact pathogen growth and metabolism. They show that mAbs specific for the polysaccharide capsule of the human pathogenic fungus Cryptococcus neoformans elicit diverse effects on fungal gene expression, lipid biosynthesis, susceptibility to amphotericin B, cellular metabolism, and protein phosphorylation. These data suggest that pathogens have the capacity to generate broad metabolic responses as a result of surface binding by pathogen-specific antibodies, effects that may hold therapeutic promise.

Ab binding alters gene expression in Cryptococcus neoformans and directly modulates fungal metabolism

Abs facilitate humoral immunity via the classical mechanisms of opsonization, complement activation, Ab-dependent cellular cytotoxicity, and toxin/viral neutralization. There is also evidence that some Abs mediate direct antimicrobial effects. For example, Ab binding to the polysaccharide capsule of the human pathogenic fungus Cryptococcus neoformans promotes opsonization but also inhibits polysaccharide release and biofilm formation. To investigate whether Ab binding affects C. neoformans directly, we analyzed fungal gene expression after binding of protective and nonprotective mAbs. The 2 IgM Abs and 1 IgG1 Ab tested each induced different changes in gene expression. The protective IgG1 mAb upregulated genes encoding proteins involved in fatty acid synthesis, the protective IgM mAb downregulated genes encoding proteins required for protein translation, and the nonprotective IgM mAb had modest effects on gene expression. Differences in gene expression correlated with mAb binding to different locations of the capsule. Of the 3 Abs tested, the protective IgG1 mAb bound to C. neoformans closest to the cell wall, produced specific differences in the pattern of phosphorylated proteins, caused changes in lipid metabolism, and resulted in increased susceptibility to the antifungal drug amphotericin B. These results suggest what we believe to be a new mode of action for Ab-mediated immunity and raise the possibility that immunoglobulins mediate cross talk between microbes and hosts through their effects on microbial metabolism.

Monoclonal antibody-based therapies for microbial diseases

The monoclonal antibody (mAb) revolution that currently provides many new options for the treatment of neoplastic and inflammatory diseases has largely bypassed the field of infectious diseases. Only one mAb is licensed for use against an infectious disease, although there are many in various stages of development. This situation is peculiar given that serum therapy was one of the first effective treatments for microbial diseases and that specific antibodies have numerous antimicrobial properties. The underdevelopment and underutilization of mAb therapies for microbial diseases has various complex explanations that include the current availability of antimicrobial drugs, small markets, high costs and microbial antigenic variation. However, there are signs that the climate for mAb therapeutics in infectious diseases is changing given increasing antibiotic drug resistance, the emergence of new pathogenic microbes for which no therapy is available, and development of mAb cocktail formulations. Currently, the major hurdle for the widespread introduction of mAb therapies for microbial diseases is economic, given the high costs of immunoglobulin preparations and relatively small markets. Despite these obstacles there are numerous opportunities for mAb development against microbial diseases and the development of radioimmunotherapy provides new options for enhancing the magic bullet. Hence, there is cautious optimism that the years ahead will see more mAbs in clinical use against microbial diseases.

Successful treatment of life-threatening Candida peritonitis in a child with abdominal non-Hodgkin lymphoma using Efungumab and amphotericin B colloid dispersion

Invasive fungal infections are serious complications of cancer therapy. We present a case report of a 12-year-old boy diagnosed with abdominal non-Hodgkin lymphoma and fecal and Candida peritonitis during induction chemotherapy. The invasive mycosis was managed using a combined approach of systemic antifungal agents including efungumab and surgical interventions. Efungumab, a recombinant antibody that inhibits extracellular heat shock protein 90, was used in combination with amphotericin B colloid dispersion after the failure of standard approaches.

Antifungal therapy in infants and children with proven, probable or suspected invasive fungal infections

BACKGROUND

Invasive fungal infections are associated with significant morbidity and mortality in children. Optimal treatment strategies are yet to be defined.

OBJECTIVES

This review aims to systematically identify and summarise the effects of different antifungal therapies in children with proven, probable or suspected invasive fungal infections.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 3), MEDLINE (1966 to September 2008), EMBASE (1980 to September 2008) and CINAHL (1988 to September 2008) without language restrictions. We also handsearched reference lists and abstracts of conference proceedings and scientific meetings, and contacted authors of included studies and pharmaceutical manufacturers.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) comparing a systemic antifungal agent with a comparator (including placebo) in children (one month to 16 years) with proven, probable or suspected invasive fungal infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied selection criteria, performed quality assessment, and extracted data using an intention-to-treat approach. We synthesised data using the random-effects model and expressed results as relative risks (RR) with 95% confidence intervals (CIs).

MAIN RESULTS

We included seven trials of antifungal agents in children with prolonged fever and neutropenia (suspected fungal infection) and candidaemia or invasive candidiasis (proven fungal infection). Four trials compared a lipid preparation of amphotericin B with conventional amphotericin B (395 participants), one trial compared an echinocandin with a lipid preparation of amphotericin B (82 participants) in suspected infection; one trial compared an echinocandin with a lipid preparation of amphotericin B in children with candidaemia or invasive candidiasis (109 participants) and one trial compared different azole antifungals in children with candidaemia (43 participants). No difference in all-cause mortality and other primary endpoints (mortality related to fungal infection or complete resolution of fungal infections) were observed. No difference in breakthrough fungal infection was observed in children with prolonged fever and neutropenia.When lipid preparations and conventional amphotericin B were compared in children with prolonged fever and neutropenia, nephrotoxicity was less frequently observed with a lipid preparation (RR 0.43, 95% CI 0.21 to 0.90, P = 0.02) however substantial heterogeneity was observed (I(2) = 59%, P = 0.06). Children receiving liposomal amphotericin B were less likely to develop infusion-related reactions compared with conventional amphotericin B (chills: RR 0.37, 95% CI 0.21 to 0.64, P = 0.0005). Children receiving a colloidal dispersion were more likely to develop such reactions than with liposomal amphotericin B (chills: RR 1.76, 95% CI 1.09 to 2.85, P = 0.02). The rate of other clinically significant adverse reactions attributed to the antifungal agent (total reactions; total reactions leading to treatment discontinuation, dose reduction or change in therapy; hypokalaemia and hepatotoxicity) were not significantly different. When echinocandins and lipid preparations were compared, the rate of clinically significant adverse reactions (total reactions; total reactions leading to treatment discontinuation, dose reduction or change in therapy) were not significantly different.

AUTHORS' CONCLUSIONS

Limited paediatric data are available comparing antifungal agents in children with proven, probable or suspected invasive fungal infection. No differences in mortality or treatment efficacy were observed when antifungal agents were compared. Children are less likely to develop nephrotoxicity with a lipid preparation of amphotericin B compared with conventional amphotericin B. Further comparative paediatric antifungal drug trials and epidemiological and pharmacological studies are required highlighting the differences between neonates, children and adults with invasive fungal infections.

Reverse genetics in Candida albicans predicts ARF cycling is essential for drug resistance and virulence

Candida albicans, the major fungal pathogen of humans, causes life-threatening infections in immunocompromised individuals. Due to limited available therapy options, this can frequently lead to therapy failure and emergence of drug resistance. To improve current treatment strategies, we have combined comprehensive chemical-genomic screening in Saccharomyces cerevisiae and validation in C. albicans with the goal of identifying compounds that can couple with the fungistatic drug fluconazole to make it fungicidal. Among the genes identified in the yeast screen, we found that only AGE3, which codes for an ADP-ribosylation factor GTPase activating effector protein, abrogates fluconazole tolerance in C. albicans. The age3 mutant was more sensitive to other sterols and cell wall inhibitors, including caspofungin. The deletion of AGE3 in drug resistant clinical isolates and in constitutively active calcineurin signaling mutants restored fluconazole sensitivity. We confirmed chemically the AGE3-dependent drug sensitivity by showing a potent fungicidal synergy between fluconazole and brefeldin A (an inhibitor of the guanine nucleotide exchange factor for ADP ribosylation factors) in wild type C. albicans as well as in drug resistant clinical isolates. Addition of calcineurin inhibitors to the fluconazole/brefeldin A combination only initially improved pathogen killing. Brefeldin A synergized with different drugs in non-albicans Candida species as well as Aspergillus fumigatus. Microarray studies showed that core transcriptional responses to two different drug classes are not significantly altered in age3 mutants. The therapeutic potential of inhibiting ARF activities was demonstrated by in vivo studies that showed age3 mutants are avirulent in wild type mice, attenuated in virulence in immunocompromised mice and that fluconazole treatment was significantly more efficacious when ARF signaling was genetically compromised. This work describes a new, widely conserved, broad-spectrum mechanism involved in fungal drug resistance and virulence and offers a potential route for single or improved combination therapies.

Candida albicans is a fungus that normally resides as part of the microflora in the human gut. Candida species can cause superficial infections like thrush in the healthy human population and life-threatening invasive infections in immunocompromised patients. Fungal infections are often treated with azole drugs, but due to the fungistatic nature of these agents, C. albicans can develop drug resistance, leading to therapy failure. To improve the action of azoles and convert them into fungicidal drugs, we first systematically analyzed the genetic requirements for tolerance to one such azole drug, fluconazole. We show, both genetically and pharmacologically, that components of the ARF cycling machinery are critical in mediating both azole and echinocandin tolerance in C. albicans as well as several other pathogenic Candida species and in the pathogenic mold Aspergillus fumigatus. We highlight the importance of ARF cycling in drug resistance by showing that genetic compromise of ARF functions overrides common drug resistance mechanisms in clinical samples and other key regulators of azole/echinocandin tolerance. We validated the therapeutic potential of ARF cycling in two mouse models and provide evidence that drug treatment is more efficacious when ARF activities are genetically compromised. Our study demonstrates a new mechanism involved in two important aspects of the biology of human fungal pathogens and provides a potential route for improved antifungal therapies.

Candida albicans, Cryptococcus neoformans or Aspergillus fumigatus induces an antifungal activity in mouse serum, which is different from transferrin

It has been reported that administration of Candida albicans into mouse induces an antifungal activity in serum, which has been identified as transferrin. In the present study, we show that not only C. albicans, but also other fungus such as Cryptococcus neoformans or Aspergillus fumigatus similarly can induce an antifungal activity in mouse serum. This antifungal activity was inhibited by the addition of ferrous ion, indicating that the growth inhibition of C. albicans was due to deficiency of ferrous ion, which may be caused by transferrin. Indeed, addition of transferrin in an in vitro assay system using RPMI1640 culture medium inhibited the growth of C. albicans, C. neoformans or A. fumigatus. However, when C. albicans was grown in RPMI1640 medium with 10% fetal bovine serum (FBS), transferrin was unable to inhibit the growth of C. albicans, in sharp contrast, when C. albicans treated mouse serum was added instead of FBS, the growth of the organism was inhibited. Similar results were obtained when C. neoformans or A. fumigatus was used. Taken together, the results suggest that antifungal activity induced by C. albicans, C. neoformans or A. fumigatus was not due to transferrin but likely due to other unknown serum proteins, which may cut off the source of iron for the growth of these fungi.

Invasive candidiasis and candidemia: from current opinions to future perspectives

Candida spp. are the fourth most common cause of nosocomial bloodstream infections in the United States, as well as the single most important cause of opportunistic fungal infections worldwide. A delayed diagnosis of invasive candidiasis and/or inadequate treatment choice is associated with high mortality rates and prolonged hospital stays. Even though the antifungal armamentarium has been broadened significantly over the last years, the best options for diagnosing and treating invasive candidiasis still remain a matter of discussion. In this article we present and analyze current evidence on the epidemiology, diagnostic methods and treatment options of invasive candidiasis, with a focus on results from randomized clinical trials. Finally, the reader is provided with a brief overview on promising clinical trial designs and antifungals that might shape the treatment of invasive candidiasis in the years to come.

Efungumab: A Novel Agent in the Treatment of Invasive Candidiasis

Objective:

To review the use of efungumab as an adjunctive agent in the treatment of invasive candidiasis (IC) and to provide guidance on formulary placement.

Data Sources:

Searches of MEDLINE (1966–June 2009) and EMBASE (1974–June 2009) were conducted using the terms efungumab, Mycograb, heat shock protein 90, and invasive candidiasis. Other resources included www.clinicaltrials.gov and article bibliographies.

Study Selection and Data Extraction:

All studies and case reports evaluating efungumab use in IC were included. Literature review was limited to the English language.

Data Synthesis:

Efungumab is a monoclonal antibody targeted against heat shock protein 90 (HSP 90). It binds to HSP 90, preventing a conformational change needed for fungal viability. In vitro data show that HSP 90 inhibition may decrease resistance against antifungal agents and increase antifungal activity. Efungumab shows activity against Candida spp. when used alone and synergism when combined with fluconazole, caspofungin, and amphotericin B. A randomized controlled trial evaluated combination therapy of efungumab 1 mg/kg twice daily and liposomal amphotericin B versus amphotericin B therapy alone. At day 10, a favorable response was seen in 84% of patients in the efungumab group compared with 48% of patients in the placebo group (OR 5.76; 95% CI 2.4 to 13.8). Mortality at day 33 was also lower in the efungumab group, 4% versus 18%, respectively (OR 0.168; 95% CI 0.036 to 0.797). Although adverse effects were similar in this trial (10% vs 7%), case reports revealed an increased incidence of blood pressure fluctuations. Cytokine release syndrome has also been linked to efungumab use, warranting further exploration of its safety.

Conclusions:

Efungumab is a new antifungal agent with a novel mechanism of action. Available clinical data and synergy studies support the use of efungumab in combination with other antifungal agents for the treatment of IC. Further safety data are needed before formulary recommendations can be made.

Recent advances in antifungal prevention and treatment

Invasive fungal infections are important causes of morbidity and mortality in patients with bone marrow failure syndromes and hematological malignancies, or who are undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Current epidemiological trends indicate a shift toward infections by Aspergillus spp., non-albicans Candida spp., and previously uncommon fungal pathogens that have decreased susceptibility to the available antifungal agents. The last two decades have seen substantial improvements in the clinical, laboratory, and radiological diagnosis of these infections and the development of new antifungal compounds. Progress has been made in establishing disease definitions and paradigms for antifungal intervention and in the design and conduct of interventional clinical trials. Collectively, these advances have led to major but ongoing changes in the management of patients at risk of or being affected by invasive fungal infections. This article reviews current approaches to prevention and treatment of opportunistic fungal infections in immunocompromised patients with hematological disorders and discusses novel approaches to antifungal chemotherapy and adjunctive treatments.