Efficacy, safety, and plasma pharmacokinetics of escalating dosages of intravenously administered ravuconazole lysine phosphoester for treatment of experimental pulmonary aspergillosis in persistently neutropenic rabbits

Non-Aspergillus Hyaline Molds: A Host-Based Perspective of Emerging Pathogenic Fungi Causing Sinopulmonary Diseases

The incidence of invasive sino-pulmonary diseases due to non-Aspergillus hyaline molds is increasing due to an enlarging and evolving population of immunosuppressed hosts as well as improvements in the capabilities of molecular-based diagnostics. Herein, we review the following opportunistic pathogens known to cause sinopulmonary disease, the most common manifestation of hyalohyphomycosis: Fusarium spp., Scedosporium spp., Lomentospora prolificans, Scopulariopsis spp., Trichoderma spp., Acremonium spp., Paecilomyces variotii, Purpureocillium lilacinum, Rasamsonia argillacea species complex, Arthrographis kalrae, and Penicillium species. To facilitate an understanding of the epidemiology and clinical features of sino-pulmonary hyalohyphomycoses in the context of host immune impairment, we utilized a host-based approach encompassing the following underlying conditions: neutropenia, hematologic malignancy, hematopoietic and solid organ transplantation, chronic granulomatous disease, acquired immunodeficiency syndrome, cystic fibrosis, and healthy individuals who sustain burns, trauma, or iatrogenic exposures. We further summarize the pre-clinical and clinical data informing antifungal management for each pathogen and consider the role of adjunctive surgery and/or immunomodulatory treatments to optimize patient outcome.

Modeling Invasive Aspergillosis: How Close Are Predicted Antifungal Targets?

Animal model systems are a critical component of the process of discovery and development of new antifungal agents for treatment and prevention of invasive aspergillosis. The persistently neutropenic rabbit model of invasive pulmonary aspergillosis (IPA) has been a highly predictive system in identifying new antifungal agents for treatment and prevention of this frequently lethal infection. Since its initial development, the persistently neutropenic rabbit model of IPA has established a strong preclinical foundation for dosages, drug disposition, pharmacokinetics, safety, tolerability, and efficacy for deoxycholate amphotericin B, liposomal amphotericin B, amphotericin B lipid complex, amphotericin B colloidal dispersion, caspofungin, micafungin, anidulafungin, voriconazole, posaconazole, isavuconazole, and ibrexafungerp in treatment of patients with invasive aspergillosis. The findings of combination therapy with a mould-active triazole and an echinocandin in this rabbit model also predicted the outcome of the clinical trial for voriconazole plus anidulafungin for treatment of IPA. The plasma pharmacokinetic parameters and tissue disposition for most antifungal agents approximate those of humans in persistently neutropenic rabbits. Safety, particularly nephrotoxicity, has also been highly predictive in the rabbit model, as exemplified by the differential glomerular filtration rates observed in animals treated with deoxycholate amphotericin B, liposomal amphotericin B, amphotericin B lipid complex, and amphotericin B colloidal dispersion. A panel of validated outcome variables measures therapeutic outcome in the rabbit model: residual fungal burden, markers of organism-mediated pulmonary injury (lung weights and infarct scores), survival, and serum biomarkers. In selected antifungal studies, thoracic computerized tomography (CT) is also used with diagnostic imaging algorithms to measure therapeutic response of pulmonary infiltrates, which exhibit characteristic radiographic patterns, including nodules and halo signs. Further strengthening the predictive properties of the model, therapeutic response to successfully developed antifungal agents for treatment of IPA has been demonstrated over the past two decades by biomarkers of serum galactomannan and (1→3)-β-D-glucan with patterns of resolution, that closely mirror those documented responses in patients with IPA. The decision to move from laboratory to clinical trials should be predicated upon a portfolio of complementary and mutually validating preclinical laboratory animal models studies. Other model systems, including those in mice, rats, and guinea pigs, are also valuable tools in developing clinical protocols. Meticulous preclinical investigation of a candidate antifungal compound in a robust series of complementary laboratory animal models will optimize study design, de-risk clinical trials, and ensure tangible benefit to our most vulnerable immunocompromised patients with invasive aspergillosis.

Discovery of Anti-Amoebic Inhibitors from Screening the MMV Pandemic Response Box on Balamuthia mandrillaris, Naegleria fowleri, and Acanthamoeba castellanii

Pathogenic free-living amoebae, Balamuthia mandrillaris, Naegleria fowleri, and several Acanthamoeba species are the etiological agents of severe brain diseases, with case mortality rates > 90%. A number of constraints including misdiagnosis and partially effective treatments lead to these high fatality rates. The unmet medical need is for rapidly acting, highly potent new drugs to reduce these alarming mortality rates. Herein, we report the discovery of new drugs as potential anti-amoebic agents. We used the CellTiter-Glo 2.0 high-throughput screening methods to screen the Medicines for Malaria Ventures (MMV) Pandemic Response Box in a search for new active chemical scaffolds. Initially, we screened the library as a single-point assay at 10 and 1 µM. From these data, we reconfirmed hits by conducting quantitative dose-response assays and identified 12 hits against B. mandrillaris, 29 against N. fowleri, and 14 against A. castellanii ranging from nanomolar to low micromolar potency. We further describe 11 novel molecules with activity against B. mandrillaris, 22 against N. fowleri, and 9 against A. castellanii. These structures serve as a starting point for medicinal chemistry studies and demonstrate the utility of phenotypic screening for drug discovery to treat diseases caused by free-living amoebae.

Animal Models of Aspergillosis

Aspergillosis is an airborne fungal disease caused by Aspergillus spp., a group of ubiquitous molds. This disease causes high morbidity and mortality in both humans and animals. The growing importance of this infection over recent decades has created a need for practical and reproducible models of aspergillosis. The use of laboratory animals provides a platform to understand fungal virulence and pathophysiology, assess diagnostic tools, and evaluate new antifungal drugs. In this review, we describe the fungus, various Aspergillus-related diseases in humans and animals and various experimental animal models. Overall, we highlight the advantages and limitations of the animal models, the experimental variables that can affect the course of the disease and the reproducibility of infection, and the critical need for standardization of the species, immunosuppressive drugs, route of infection, and diagnostic criteria to use.

Endpoint Assessment in Rabbit Models of Invasive Pulmonary Aspergillosis and Mucormycosis

Multiple animal models have been developed to study the pathogenesis of invasive pulmonary aspergillosis, as well as to evaluate the efficacy, pharmacokinetics, and pharmacodynamics of various antifungal agents and vaccines. Each model is beneficial depending on the questions that are asked. In this chapter, we will discuss the endpoints assessment of the persistently neutropenic rabbit models of invasive pulmonary aspergillosis and invasive pulmonary mucormycosis.

Animal Models for Studying Triazole Resistance in Aspergillus fumigatus

Infections caused by triazole-resistant Aspergillus fumigatus are associated with a higher probability of treatment failure and mortality. Because clinical experience in managing these infections is still limited, mouse models of invasive aspergillosis fulfill a critical void for studying treatment regimens designed to overcome resistance. The type of immunosuppression, the route of infection, the timing of antifungal administration, and the end points used to assess antifungal activity affect the interpretation of data from these models. Nevertheless, these models provide important insights that help guide treatment decisions in patients with triazole-resistant invasive aspergillosis. Animal models confirmed that a high triazole minimal inhibitory concentration corresponded with triazole treatment failure and that the efficacy of other classes of drugs, such as the polyenes and echinocandins, was not affected by the presence of triazole resistance mutations. Furthermore, the feasibility of triazole dose escalation, combination therapy, and prophylaxis were explored as strategies to overcome resistance.

Potential of Ravuconazole and its Prodrugs as the New OralTherapeutics for Onychomycosis

Onychomycosis is a fungal infection of the nail apparatus caused by dermatophytes, Candida and non-dermatophytic molds. It is highly prevalent in the general population worldwide and also responsible for significant morbidity and complications and does not usually cure itself. Thus, the condition needs to be treated in view of physical and psychological problems produced. Currently, oral medications using terbinafine are the most effective therapy, but it has relatively limited therapeutic success, particularly for long-term management. Such existing oral therapies are associated with high recurrence rates and treatment failure, as well as with potential adverse events and drug-drug interactions. In the light of these issues, development of more efficacious and safer alternatives for the treatment of onychomycosis is warranted.Ravuconazole and its prodrugs are promising new drug candidates for oral therapy of onychomycosis, among which a water-soluble prodrug, mono-lysine phosphoester derivative (E1224 or BFE1224) is in the most advanced stage of clinical development; a Phase II dose-finding study has been successfully completed and Phase III comparative studies are in progress in Japan.This review aims to summarize our current status of knowledge and information on ravuconazole and its prodrugs, particularly BFE1224, as the potential oral treatment option for onychomycosis. It also summarize the clinical features of onychomycosis with particular stress on its etiology, epidemiology, and current therapeutic options and their limitations. Given its clinical usefulness, BFE1224 may become a valuable addition to the current armamentarium for the treatment of onychomycosis.

Rodent Models of Invasive Aspergillosis due to Aspergillus fumigatus: Still a Long Path toward Standardization

Invasive aspergillosis has been studied in laboratory by the means of plethora of distinct animal models. They were developed to address pathophysiology, therapy, diagnosis, or miscellaneous other concerns associated. However, there are great discrepancies regarding all the experimental variables of animal models, and a thorough focus on them is needed. This systematic review completed a comprehensive bibliographic analysis specifically-based on the technical features of rodent models infected with Aspergillus fumigatus. Out the 800 articles reviewed, it was shown that mice remained the preferred model (85.8% of the referenced reports), above rats (10.8%), and guinea pigs (3.8%). Three quarters of the models involved immunocompromised status, mainly by steroids (44.4%) and/or alkylating drugs (42.9%), but only 27.7% were reported to receive antibiotic prophylaxis to prevent from bacterial infection. Injection of spores (30.0%) and inhalation/deposition into respiratory airways (66.9%) were the most used routes for experimental inoculation. Overall, more than 230 distinct A. fumigatus strains were used in models. Of all the published studies, 18.4% did not mention usage of any diagnostic tool, like histopathology or mycological culture, to control correct implementation of the disease and to measure outcome. In light of these findings, a consensus discussion should be engaged to establish a minimum standardization, although this may not be consistently suitable for addressing all the specific aspects of invasive aspergillosis.

Prognostic value of galactomannan: current evidence for monitoring response to antifungal therapy in patients with invasive aspergillosis

Galactomannan (GM) is a polysaccharide present in the cell wall of Aspergillus spp. that is released during growth of the organism. It has been successfully used to aide in the diagnosis of invasive aspergillosis allowing for earlier recognition of disease compared to conventional methods. Since its implementation in the clinic as a diagnostic tool, GM has been used in experimental models to measure therapeutic response. Several clinical studies describe the prognostic value of GM. Herein, we review the evidence supporting the utilization of GM antigen as a biomarker to measure response to systemic antifungal therapy.

Anti-transferrin receptor-modified amphotericin B-loaded PLA-PEG nanoparticles cure Candidal meningitis and reduce drug toxicity

Fatal fungal infections in central nervous system (CNS) can occur through hematogenous spread or direct extension. At present, hydrophobic amphotericin B (AMB) is the most effective antifungal drug in clinical trials. However, AMB is hydrophobic and therefore penetrates poorly into the CNS, and therapeutic levels of AMB are hard to achieve. The transferrin receptor (TfR/CD71) located at the blood-brain barrier mediates transferrin transcytosis. In order to enhance the receptor-mediated delivery of AMB into CNS with therapeutic level, an anti-TfR antibody (OX26)-modified AMB-loaded PLA (poly[lactic acid])-PEG (polyethylene glycol)-based micellar drug delivery system was constructed. The prepared OX26-modified AMB-loaded nanoparticles (OX26-AMB-NPs) showed significant reduction of CNS fungal burden and an increase of mouse survival time. In conclusion, OX26-AMB-NPs represent a promising novel drug delivery system for intracerebral fungal infection.

Efficacy of ravuconazole in a murine model of vaginitis by Candida albicans

BACKGROUND

The incidence of vulvovaginal candidiasis, a common infection among healthy women primarily caused by the yeast Candida albicans, has increased significantly in recent years.

AIMS

The purpose of this study was to compare the efficacy of ravuconazole (RVC) and fluconazole (FLC) in the treatment of experimental C. albicans vaginitis.

METHODS

Forty isolates of C. albicans were screened for their in vitro susceptibility to RVC and FLC. A strain of C. albicans that was resistant to FLC (minimum inhibitory concentration [MIC] of >64 μg/ml) was selected for the in vivo study. Treatment regimens for the murine vaginal infection model were (1) 1, 5, 10, and 20 mg/kg RVC once daily, (2) 20 mg/kg RVC twice daily, (3) 20 mg/kg FLC once daily, and (4) 20 mg/kg FLC twice daily.

RESULTS

The geometric means of the MIC values at 48 h for all isolates tested were 0.05 and 0.5 μg/ml for RVC and FLC, respectively. Regimens of either RVC or FLC at 20 mg/kg twice daily were more effective to reduce the load of FLC-resistant C. albicans than single dose administration.

CONCLUSIONS

Complete eradication of C. albicans from the vagina was not observed with RVC or FLC treatment in the animal model, although RVC treatment showed a lower fungal concentration 14 days after drug administration.

Molecular detection and species-specific identification of medically important Aspergillus species by real-time PCR in experimental invasive pulmonary aspergillosis

Diagnosis of invasive pulmonary aspergillosis (IPA) remains a major challenge to clinical microbiology laboratories. We developed rapid and sensitive quantitative PCR (qPCR) assays for genus- and species-specific identification of Aspergillus infections by use of TaqMan technology. In order to validate these assays and understand their potential diagnostic utility, we then performed a blinded study of bronchoalveolar lavage (BAL) fluid specimens from well-characterized models of IPA with the four medically important species. A set of real-time qPCR primers and probes was developed by utilizing unique ITS1 regions for genus- and species-specific detection of the four most common medically important Aspergillus species (Aspergillus fumigatus, A. flavus, A. niger, and A. terreus). Pan-Aspergillus and species-specific qPCRs with BAL fluid were more sensitive than culture for detection of IPA caused by A. fumigatus in untreated (P < 0.0007) and treated (P ≤ 0.008) animals, respectively. For infections caused by A. terreus and A. niger, culture and PCR amplification from BAL fluid yielded similar sensitivities for untreated and treated animals. Pan-Aspergillus PCR was more sensitive than culture for detection of A. flavus in treated animals (P = 0.002). BAL fluid pan-Aspergillus and species-specific PCRs were comparable in sensitivity to BAL fluid galactomannan (GM) assay. The copy numbers from the qPCR assays correlated with quantitative cultures to determine the pulmonary residual fungal burdens in lung tissue. Pan-Aspergillus and species-specific qPCR assays may improve the rapid and accurate identification of IPA in immunocompromised patients.

Diagnostic imaging of experimental invasive pulmonary aspergillosis

Pulmonary infiltrates in neutropenic hosts with invasive aspergillosis are caused by organism-mediated tissue injury, vascular invasion, and hemorrhagic infarction. Ultrafast computed tomography (UFCT) scanning reproducibly measures these lesions in experimental invasive pulmonary aspergillosis in persistently neutropenic rabbits. The pulmonary lesion score from UFCT scanning is a useful outcome variable for measuring differences in efficacy of antifungal compounds alone and in combination, as well as the virulence of different strains and species of Aspergillus. Several studies demonstrate that the course of pulmonary lesions treated with amphotericin B, lipid formulations of amphotericin B, triazoles, echinocandins, and combination therapy measured by serial UFCT scans correlate with those measured by survival, histopathological resolution of lesions, microbiological clearance of Aspergillus fumigatus, and resolution of galactomannan index. We further developed a multidimensional volumetric imaging (MDVI) method for analysis of the volume of pulmonary infiltrates over time in response to antifungal therapy. Volumetric data by MDVI correlate with UFCT pulmonary lesion scores and validated biological endpoints. A recent pilot clinical study demonstrated the applicability of MDVI to human pulmonary fungal infections. MDVI also improves objectivity of radiological assessment of therapeutic response to antifungal therapy and merits more extensive evaluation in patients with invasive aspergillosis, as well as other fungal and bacterial pneumonias.

Rapid detection of triazole antifungal resistance in Aspergillus fumigatus

Triazole resistance in Aspergillus fumigatus is an uncommon but rising phenomenon. Susceptibility testing is rarely performed and can take 48 h or longer, which is an impediment to effective therapy. Molecular diagnostic probing of well-defined resistance mechanisms, which serve as surrogate markers, provides an alternative approach to rapidly (within hours) and efficiently identify resistant strains. The mechanisms of triazole resistance in A. fumigatus are limited to amino acid substitutions in the drug target Cyp51A and include amino acid substitutions at the positions Gly 54, Gly 138, Met 220, and Leu 98, coupled with a tandem repetition in the gene promoter. We report the development of a real-time PCR assay utilizing molecular beacons to assess triazole resistance markers in A. fumigatus. When combined in a multiplex platform, the assay provides a comprehensive evaluation of drug resistance in A. fumigatus.

Characterization and comparison of galactomannan enzyme immunoassay and quantitative real-time PCR assay for detection of Aspergillus fumigatus in bronchoalveolar lavage fluid from experimental invasive pulmonary aspergillosis

Bronchoalveolar lavage (BAL) is widely used for evaluation of patients with suspected invasive pulmonary aspergillosis (IPA). However, the diagnostic yield of BAL for detection of IPA by culture and direct examination is limited. Earlier diagnosis may be facilitated by assays that can detect Aspergillus galactomannan antigen or DNA in BAL fluid. We therefore characterized and compared the diagnostic yields of a galactomannan enzyme immunoassay (GM EIA), quantitative real-time PCR (qPCR), and quantitative cultures in experiments using BAL fluid from neutropenic rabbits with experimentally induced IPA defined as microbiologically and histologically evident invasion. The qPCR assay targeted the rRNA gene complex of Aspergillus fumigatus. The GM EIA and qPCR assay were characterized by receiver operator curve analysis. With an optimal cutoff of 0.75, the GM EIA had a sensitivity and specificity of 100% in untreated controls. A decline in sensitivity (92%) was observed when antifungal therapy (AFT) was administered. The optimal cutoff for qPCR was a crossover of 36 cycles, with sensitivity and specificity of 80% and 100%, respectively. The sensitivity of qPCR also decreased with AFT to 50%. Quantitative culture of BAL had a sensitivity of 46% and a specificity of 100%. The sensitivity of quantitative culture decreased with AFT to 16%. The GM EIA and qPCR assay had greater sensitivity than culture in detection of A. fumigatus in BAL fluid in experimentally induced IPA (P+/-0.04). Use of the GM EIA and qPCR assay in conjunction with culture-based diagnostic methods applied to BAL fluid could facilitate accurate diagnosis and more-timely initiation of specific therapy.

Newer triazole antifungal agents: pharmacology, spectrum, clinical efficacy and limitations

New triazole antifungals (voriconazole, posaconazole, ravuconazole and albaconazole) have been developed to meet the increasing need for new antifungals, and address the rising incidence of invasive fungal infections and the emergence of fungal resistance. This report describes the spectrum of activity of the newer-generation triazoles based on data from in vitro, animal and clinical studies. The authors discuss the use of these agents in combination with other antifungals, the extent of cross-resistance, their toxicity profile and pharmacokinetic properties. A total of two agents are currently available: voriconazole (which is becoming a primary treatment for the management of invasive aspergillosis) and posaconazole (which demonstrates a broad antifungal spectrum). A further two agents, albaconazole and ravuconazole, are undergoing early clinical evaluation and their future is uncertain. For all newer triazoles, concerns about emerging drug-resistant fungi and the incidence and management of breakthrough infections will dictate their role in antifungal prophylaxis and treatment.

Emerging azole antifungals

Systemic and superficial fungal infections have progressively emerged over the past few decades as an increasing cause of human disease, especially in the immunocompromised host. Control of fungal disease has proved difficult because few risk factors are potentially preventable; the population at highest risk for fungal disease, the immunocompromised patient, has been steadily increasing. There is a clear need for additional safe and effective therapeutic agents for the treatment of systemic fungal disease. A new generation of triazoles that includes voriconazole, posaconazole, ravuconazole and albaconazole has emerged and are presently in different phases of clinical investigation. These new triazoles have demonstrated a broad spectrum of activity, in particular against fungal pathogens previously resistant to previously available antifungals. This review highlights the emerging azole antifungals, both those available and in clinical development, and discusses their prospects for the future.

In vitro activity of ravuconazole against 923 clinical isolates of nondermatophyte filamentous fungi

The in vitro activities of ravuconazole against 575 clinical strains of Aspergillus spp. and 348 nondermatophyte non-Aspergillus spp. were analyzed. Ravuconazole was active against Aspergillus spp., other hyaline filamentous fungi, black molds, and some Mucorales. Species such as Scedosporium prolificans, Fusarium spp., and Scopulariopsis spp. were resistant to the triazole.

The contribution of animal models of aspergillosis to understanding pathogenesis, therapy and virulence

Animal models of aspergillosis have been used extensively to study various aspects of pathogenesis, innate and acquired host-response, disease transmission and therapy. Several different animal models of aspergillosis have been developed. Because aspergillosis is an important pulmonary disease in birds, avian models have been used successfully to study preventative vaccines. Studies done to emulate human disease have relied on models using common laboratory animal species. Guinea pig models have primarily been used in therapy studies of invasive pulmonary aspergillosis (IPA). Rabbits have been used to study IPA and systemic disease, as well as fungal keratitis. Rodent, particularly mouse, models of aspergillosis predominate as the choice for most investigators. The availability of genetically defined strains of mice, immunological reagents, cost and ease of handling are factors. Both normal and immunosuppressed animals are used routinely. These models have been used to determine efficacy of experimental therapeutics, comparative virulence of different isolates of Aspergillus, genes involved in virulence, and susceptibility to infection with Aspergillus. Mice with genetic immunological deficiency and cytokine gene-specific knockout mice facilitate studies of the roles cells, and cytokines and chemokines, play in host-resistance to Aspergillus. Overall, these models have been critical to the advancement of therapy, and our current understanding of pathogenesis and host-resistance.

Compartmental pharmacokinetics and tissue distribution of the antifungal triazole ravuconazole following intravenous administration of its di-lysine phosphoester prodrug (BMS-379224) in rabbits

OBJECTIVES

Ravuconazole is a broad-spectrum antifungal triazole in clinical development. We investigated the compartmental plasma pharmacokinetics and tissue distribution of ravuconazole following administration of its novel intravenous (i.v.) di-lysine phosphoester prodrug, BMS-379224.

METHODS

Normal catheterized rabbits received the prodrug at 1.25, 2.5, 5, 10, 20 and 40 mg/kg once daily as 5 min i.v. bolus for 8 days. Serial plasma levels were collected at days 1 and 7, and tissues were obtained 30 min after the eighth dose. Concentrations of ravuconazole were determined by a validated HPLC method. Plasma concentration data were fitted to a three-compartment pharmacokinetic model. Pharmacokinetic parameters were estimated by weighted non-linear least squares regression analysis using the WinNonlin computer program.

RESULTS

Following single dosing, ravuconazole demonstrated linear plasma pharmacokinetics across the investigated dosage range. Cmax, AUC(0-infinity), V(ss), CL and terminal half-life (means +/- SEM) ranged from 2.03 to 58.82 mg/L, 5.80 to 234.21 mg x h/L, 5.16 to 6.43 L/kg, 0.25 to 0.18 L/h/kg and 20.55 to 26.34 h, respectively. Plasma data after multiple dosing revealed non-linear disposition at the 20 and 40 mg/kg dosage levels as evidenced by a dose-dependent decrease in CL (from 0.104-0.147 to 0.030 and 0.022 L/h/kg; P = 0.1053) and an increase in the dose-normalized AUC(0-infinity) (from 2.40-3.01 up to 11.90 and 14.56 mg x h/L; P = 0.0382). Tissue concentrations 30 min after the last dose were highest in the liver (12.91-562.68 microg/g), adipose tissue (10.57-938.55 microg/g), lung (5.46-219.12 microg/g), kidney (3.95-252.44 microg/g) and brain tissue (2.37-144.85 microg/g).

CONCLUSIONS

The pharmacokinetics of ravuconazole fitted best to a three-compartment pharmacokinetic model. The compound revealed non-linear pharmacokinetics at higher dosages, indicating saturable clearance and/or protein binding. Ravuconazole displayed a long elimination half-life and achieved substantial plasma and tissue concentrations including in the brain.

New agents for invasive mycoses in children

PURPOSE OF REVIEW

Invasive fungal infections are an important cause of morbidity and mortality in immunocompromised children of all ages. This review summarizes information on new antifungal agents, including current data on their clinical use in children, as well as alternative strategies such as antifungal combination and immunomodulation therapy.

RECENT FINDINGS

Novel antifungal agents, such as the echinocandins and the second-generation triazoles, were recently introduced that exhibit promising efficacy against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. These compounds are generally well tolerated and show substantial efficacy as salvage treatment and equal or even superior efficacy compared with older azoles or amphotericin B as first-line or empiric therapy for fungal infections. Clinical studies of pharmacokinetics and efficacy of the new agents in the pediatric population are, however, limited.

SUMMARY

The response rates observed with the recently introduced drugs, although superior in some cases compared with older antifungal agents, are still far from satisfactory. The development of new antifungal compounds as well as the use of alternative approaches of combination therapy and immunomodulation should be pursued through well-designed laboratory and clinical studies in pediatric patients.

Zygomycosis (mucormycosis): emerging clinical importance and new treatments

PURPOSE OF REVIEW

New importance has been given to zygomycosis, as what was uncommon is no longer. Zygomycosis (mucormycosis) typically occurs in patients with leukemia, with solid-organ transplants or bone marrow transplants, with diabetic ketoacidosis, in those who have received steroids or are neutropenic, and after desferioxamine therapy. Often, both diagnostic and therapeutic measures are performed too late and are inadequate. Mortality rates may be as high as 80% in infected transplant recipients. Zygomycosis also appears to have made a subtle increase in incidence: up to 8% in autopsied patients with leukemia, and 2% in allogenic bone marrow transplant patients. Most infections are acquired by inhalation, ingestion, or trauma. They rapidly infarct blood vessels, resulting in necrosis of surrounding tissue. Over the past few years, new diagnostic procedures, susceptibility tests, and drugs have entered the clinic, and these advances are discussed in the review.

RECENT FINDINGS

With the rise in number of cases of 'zygomycosis', new scrutiny has been directed at the terms 'zygomycosis' and 'mucormycosis'. This review explains their differences and the attending relevance for the clinician. Diagnostic methods include new molecular detection assays and new susceptibility testing options. New treatment options will soon exist with triazole antifungal agents. The first one expected to enter clinical practice is posaconazole in 2005. Its metabolism, pharmacokinetics, in-vitro and in-vivo activity, and clinical study results are described. Finally, we present our approach to zygomycosis.

SUMMARY

This review discusses key elements to laboratory diagnostic and susceptibility procedures and new treatment options.