Evaluation of serum sandwich enzyme-linked immunosorbent assay for circulating galactomannan during caspofungin therapy: results from the caspofungin invasive aspergillosis study

Invasive aspergillosis in patients with systemic lupus erythematosus: a retrospective study on clinical characteristics and risk factors for mortality

Objective

The objective of this paper is to analyze the clinical features, outcomes, mortality risk factors, and all-cause mortalities of invasive aspergillosis (IA) in patients with systemic lupus erythematosus (SLE).

Methods

Medical records were reviewed to identify SLE patients with IA from January 2006 to June 2017, at Taipei Veterans General Hospital, Taiwan. A total of 6714 SLE patients were included. Clinical/laboratory parameters and treatment outcomes were analyzed.

Results

Four patients (19.0%) had definite and 17 had probable (81.0%) IA. Seven patients (33.3%) survived and 14 died (66.7%). Concurrently, there were 19 pneumonias (90.5%), 17 cases of other infections (81.0%), eight bacteremia (38.1%), nine cytomegalovirus (CMV, 42.7%) and six Candida (28.6%) infections. In all 55 blood cultures, 38 (69.1%) yielded gram-negative bacilli, of which carbapenem-resistant A. baumannii accounted for eight (21.1%); 17 (30.9%) yielded gram-positive cocci, of which methicillin-resistant S. aureus accounted for six (35.3%); and vancomycin-resistant Enterococcus accounted for four (23.5%). Daily steroid dose ≥ 20 mg (hazard ratio (HR) 2.00), recent pulse steroid therapy (HR 2.80), azathioprine (HR 2.00), rituximab (HR 2.00), plasmapheresis (HR 2.00), acute respiratory distress syndrome (HR 2.00), concurrent infections (HR 5.667) and CMV viremia (HR 1.75) were higher in the fatality group. All p values were less than 0.05. Septic shock ( n = 7, 50% in the fatality group) is the most common cause of mortality.

Conclusions

High daily steroid dosing, recent pulse steroid therapy, azathioprine, rituximab, concurrent infections, and CMV viremia were mortality risk factors for IA in SLE.

Galactomannan, a Surrogate Marker for Outcome in Invasive Aspergillosis: Finally Coming of Age

Detection of galactomannan has become widely available for diagnosing invasive aspergillosis. The test characteristics, using the Platelia™ enzyme-immunoassay, have been well described. This assay could potentially also be useful for the early evaluation of the efficacy of antifungal therapy and for predicting the outcome in terms of response and survival. In this systematic review, we assessed the available evidence for the use of serum galactomannan at baseline as a prognostic marker, and the predictive value of serum galactomannan kinetics after initiation of antifungal therapy. Overall, serum galactomannan at baseline and galactomannan kinetics appear to be good predictors of therapy response and survival. However, breakpoints for predicting therapy failure and validation in different patient populations are still lacking.

Practice Guidelines for the Diagnosis and Management of Aspergillosis: 2016 Update by the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.

Invasive pulmonary aspergillosis

In susceptible patients, invasive aspergillosis has a high incidence and a mortality of up to 80%. The diagnosis of this condition is difficult, especially in the early stages of the disease and, as a consequence, antifungal therapy, despite its expense and toxicity, is often initiated empirically. Until recently, there were very few effective antifungal agents for established invasive aspergillosis, but the introduction of two new drugs, voriconazole and caspofungin, has increased the treatment options. These newer antifungal therapies, combined with improved early diagnosis due to the introduction of newer microbiologic techniques, offer the hope that there will be a significant improvement in the substantial morbidity and mortality associated with invasive aspergillosis over the next 5 years.

Current issues in the clinical management of invasive aspergillosis--the AGIHO, DMykG, ÖGMM and PEG web-based survey and expert consensus conference 2009

The objectives of this study were to identify unsolved issues in the management of invasive aspergillosis, identify controversies and achieve consensus. The German Speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMykG) invited other German infectious diseases (ID) and mycological societies to submit unsolved issues concerning the diagnosis and treatment of invasive aspergillosis. Based on these contributions, a digital web-based questionnaire of 12 questions on Aspergillus spp. was designed to be completed by experts of the participating societies. Controversial results were identified by a mathematical model and were discussed at a consensus conference during the 43rd Annual Meeting of the DMykG in Cologne, Germany. Forty-two individuals completed the questionnaire. Analysis showed a strong consensus on effective preventive measures, choice of antifungal agents for pre-emptive, empiric and targeted treatment, as well as the evaluation of early chest CT control scans as a measure of treatment response assessment. Opinions on the indication for a pulmonary biopsy of a halo sign in high-risk neutropenic patients and on the role of Aspergillus spp. PCR as well as galactomannan from serum in the assessment of treatment duration diverged in spite of discussion such that a consensus could not be reached. Using a recently published two-step approach - web-based survey plus classical panel discussion - expert consensus was achieved on 10 of 12 questions concerning the diagnosis and treatment of invasive aspergillosis.

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.

Primary antifungal prophylaxis in acute myeloblastic leukemia and myelodysplastic syndrome--still an open question?

In this review, we aim to compare different early treatment strategies of invasive fungal diseases in patients undergoing induction chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome. Three treatment approaches--prophylactic, empiric, and preemptive treatment--are subject to continuous discussion among physicians treating patients at risk. Considering the available clinical basis of evidence, we opt for antifungal prophylaxis with posaconazole 200 mg tid po as our primary prophylactic strategy, while the employment of preemptive treatment should be delayed until more accurate diagnostic tools become available. In addition to antifungal prophylaxis, empiric treatment with caspofungin or L-AmB may be administered to patients with fever resistant to broad-spectrum antibiotic treatment and without radiographic findings typical of invasive fungal disease.

Paradoxical echinocandin activity: a limited in vitro phenomenon?

The echinocandins have been a welcome addition for the treatment of invasive fungal infections. Despite their excellent safety profile and clinical efficacy, concerns exist regarding an attenuation of activity at higher concentrations, known as the paradoxical effect. In vitro studies have reported this phenomenon against both Candida and Aspergillus species. Recent data have also demonstrated this effect to be species-related and echinocandin specific. Although not completely understood, studies have pointed towards involvement of the protein kinase C cell wall integrity pathway as well as increases in cell wall chitin content as potential mechanisms responsible for this phenomenon. Increases in galactomannan have been reported in vitro and in vivo following echinocandin exposure. Although some in vivo studies of invasive aspergillosis have also reported a paradoxical increase in other markers of invasive disease and fungal burden with echinocandin therapy, these observations are inconsistent. The paradoxical effect has also not been demonstrated clinically. Thus, the clinical implications of the paradoxical attenuation of echinocandin activity at elevated concentrations remain unknown. A complete understanding of this effect may further our knowledge of fungal responses to echinocandin cell wall damage and potentially improve treatment strategies.

Galactomannan detection for invasive aspergillosis in immunocompromized patients

BACKGROUND

Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mycosis in immunocompromized patients. A test for IA needs to be not too invasive and not too big a burden for the already weakened patient. The serum galactomannan ELISA seems to have potential for both requirements.

OBJECTIVES

To obtain summary estimates of the diagnostic accuracy of galactomannan detection in serum for the diagnosis of IA.

SEARCH STRATEGY

We searched MEDLINE, EMBASE and Web of Science with both Medical Headings and text words for both aspergillosis and the sandwich ELISA. We checked reference lists of included studies and review articles for additional studies.

SELECTION CRITERIA

Cross-sectional studies, case-control designs and consecutive series of patients assessing the diagnostic accuracy of galactomannan detection for the diagnosis of IA in patients with neutropenia or patients whose neutrophils are functionally compromised were included. The reference standard was composed of the criteria given by the European Organization for Research and Treatment of Cancer (EORTC) and the Mycoses Study Group (MSG).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed quality and extracted data

MAIN RESULTS

Thirty studies were included in the meta-analyses, with a median prevalence of IA (proven or probable) of 7.7%. Seven of these (901 patients) reported results for an Optical Density Index (ODI) of 0.5 as cut-off value. The overall sensitivity in these studies was 78% (61% to 89%) and overall specificity was 81% (72% to 88%). Twelve studies (1744 patients) reported the results for cut-off value of 1.0 ODI, overall sensitivity was 75% (59% to 86%) and mean specificity 91% (84% to 95%). Seventeen studies (2600 patients) reported the results for cut-off value 1.5 ODI, sensitivity was 64% (50% to 77%) and mean specificity 95% (91% to 97%).

AUTHORS' CONCLUSIONS

At a cut-off value 0.5 ODI in a population of 100 patients with a disease prevalence of 8% (overall median prevalence), 2 patients who have IA, will be missed (sensitivity 78%, 22% false negatives), and 17 patients will be treated or further referred unnecessarily (specificity of 81%, 19% false negatives). If we use the test at cut-off value 1.5 in the same population, that will mean that 3 IA patients will be missed (sensitivity 64%, 36% false negatives) and 5 patients will be treated or referred unnecessarily (specificity of 95%, 5% false negatives). These numbers should however be interpreted with caution, because the results were very heterogeneous.

Establishing in vitro-in vivo correlations for Aspergillus fumigatus: the challenge of azoles versus echinocandins

Two clinical isolates of Aspergillus fumigatus, designated AT and DK, were recently obtained from patients failing caspofungin and itraconazole therapy, respectively. The isolates were tested by microdilution for susceptibility to itraconazole, voriconazole, posaconazole, ravuconazole, and caspofungin and by Etest for susceptibility to amphotericin B and caspofungin. Susceptibility testing documented that the DK isolate was azole resistant (itraconazole and posaconazole MICs, >4 microg/ml; voriconazole MIC, 2 microg/ml; ravuconazole MIC, 4 microg/ml), and the resistance was confirmed in a hematogenous mouse model, with mortality and the galactomannan index as the primary and secondary end points. Sequencing of the cyp51A gene revealed the M220K mutation, conferring multiazole resistance. The Etest, but not microdilution, suggested that the AT isolate was resistant to caspofungin (MIC, >32 microg/ml). In the animal model, this isolate showed reduced susceptibility to caspofungin. Sequencing of the FKS1 gene revealed no mutations; the enzyme retained full sensitivity in vitro; and investigation of the polysaccharide composition showed that the beta-(1,3)-glucan proportion was unchanged. However, gene expression profiling by Northern blotting and real-time PCR demonstrated that the FKS gene was expressed at a higher level in the AT isolate than in the susceptible control isolate. To our knowledge, this is the first report to document the presence of multiazole-resistant clinical isolates in Denmark and to demonstrate reduced susceptibility to caspofungin in a clinical A. fumigatus isolate with increased expression of the FKS gene. Further research to determine the prevalence of resistance in A. fumigatus worldwide, and to develop easier and reliable tools for the identification of such isolates in routine laboratories, is warranted.

Revised definitions of invasive fungal disease from the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group

BACKGROUND

Invasive fungal diseases are important causes of morbidity and mortality. Clarity and uniformity in defining these infections are important factors in improving the quality of clinical studies. A standard set of definitions strengthens the consistency and reproducibility of such studies.

METHODS

After the introduction of the original European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group definitions, advances in diagnostic technology and the recognition of areas in need of improvement led to a revision of this document. The revision process started with a meeting of participants in 2003, to decide on the process and to draft the proposal. This was followed by several rounds of consultation until a final draft was approved in 2005. This was made available for 6 months to allow public comment, and then the manuscript was prepared and approved.

RESULTS

The revised definitions retain the original classifications of "proven," "probable," and "possible" invasive fungal disease, but the definition of "probable" has been expanded, whereas the scope of the category "possible" has been diminished. The category of proven invasive fungal disease can apply to any patient, regardless of whether the patient is immunocompromised, whereas the probable and possible categories are proposed for immunocompromised patients only.

CONCLUSIONS

These revised definitions of invasive fungal disease are intended to advance clinical and epidemiological research and may serve as a useful model for defining other infections in high-risk patients.

Attenuation of echinocandin activity at elevated concentrations: a review of the paradoxical effect

PURPOSE OF REVIEW

The echinocandins have been a welcome addition for the treatment of invasive fungal infections caused by Candida and Aspergillus species. Despite their excellent safety profile and clinical efficacy, concerns exist regarding an attenuation of activity at higher concentrations, known as the paradoxical effect. This article will review the literature describing this effect, the potential mechanisms responsible for it, and the clinical implications of this phenomenon.

RECENT FINDINGS

In-vitro studies have reported a paradoxical effect at higher concentrations against both Candida and Aspergillus species. Recent data have demonstrated this effect in Candida to be species related and echinocandin specific. Although not completely understood, studies have pointed towards involvement of the protein kinase C cell wall integrity and calcineurin pathways as well as increases in cell wall chitin content as potential mechanisms behind the effect. Although some in-vivo studies with echinocandins have reported a paradoxical increase in markers of invasive disease, clinical data are scarce.

SUMMARY

The clinical implications of the paradoxical attenuation of echinocandin activity observed in vitro and in vivo remain unknown. A complete understanding of this effect may further our knowledge of fungal responses to echinocandin cell wall damage and potentially improve treatment strategies.

Invasive aspergillosis: epidemiology, diagnosis and management in immunocompromised patients

Morbidity and mortality caused by invasive Aspergillus infections are increasing. This is because of the higher number of patients with malignancies treated with intensive immunosuppressive therapy regimens as well as their improved survival from formerly fatal bacterial infections, and the rising number of patients undergoing allogeneic haematopoietic stem cell or organ transplantation. Early initiation of effective systemic antifungal treatment is essential for a successful clinical outcome in these patients; however, clinical clues for diagnosis are sparse and early microbiological proof of invasive aspergillosis (IA) is rare. Clinical diagnosis is based on pulmonary CT scan findings and non-culture based diagnostic techniques such as galactomannan or DNA detection in blood or bronchoalveolar lavage samples. Most promising outcomes can be expected in patients at high risk for aspergillosis in whom antifungal treatment has been started pre-emptively, backed up by laboratory and imaging findings. The gold standard of systemic antifungal treatment is voriconazole, which has been proven to be significantly superior to conventional amphotericin B and has led to a profound improvement of survival rates in patients with cerebral aspergillosis. Liposomal amphotericin B at standard dosages appears to be a suitable alternative for primary treatment, while caspofungin, amphotericin B lipid complex or posaconazole have shown partial or complete response in patients who had been refractory to or intolerant of primary antifungal therapy. Combination therapy with two antifungal compounds may be a promising future strategy for first-line treatment. Lung resection helps to prevent fatal haemorrhage in single patients with pulmonary lesions located in close proximity to larger blood vessels, but is primarily considered for reducing the risk of relapse during subsequent periods of severe immunosuppression. Strict reverse isolation appears to reduce the incidence of aspergillosis in allogeneic stem cell transplant recipients and patients with acute myeloid leukaemia undergoing aggressive anticancer therapy. Well designed, prospective randomised studies on infection control measures effective to prevent aspergillosis are lacking. Prophylactic systemic antifungal treatment with posaconazole significantly improves survival and reduces IA in acute myeloid leukaemia patients and reduces aspergillosis incidence rates in patients with intermediate-to-severe graft-versus-host reaction emerging after allogeneic haematopoietic stem cell transplantation. Voriconazole prophylaxis may be suitable for prevention of IA as well; however, the results of large clinical trials are still awaited.

Estado actual del diagnóstico precoz de las infecciones invasoras causadas por Aspergillus y otros hongos filamentosos emergentes

The usefulness of surrogate markers in the diagnosis of invasive fungal infections caused by Aspergillus and other emerging mycelial fungi is based on the ability of surrogate markers to detect the infection caused by different species of mycelial fungi. Conventional microbiological methods for diagnosis of fungal disease are slow and insensitive. Antigen based assays or measurement of (1-3)-beta-D-glucan in blood have been developed and validated in clinical laboratories. We review these diagnostic contemporary tools, their clinical application and impact.

Caspofungin as salvage monotherapy for invasive aspergillosis in patients with haematological malignancies or following allogeneic stem cell transplantation: efficacy and concomitant cyclosporin A

Caspofungin (CAS) has shown efficacy as salvage monotherapy for invasive aspergillosis (IA) in two open label non-comparative trials. The association between hepatotoxicity and concomitant use of CAS and cyclosporin A (CsA) has not been fully elucidated. We report results on CAS efficacy in the first cohort from outside Europe and USA and the interaction between CAS and CsA. We retrospectively reviewed the charts of all patients with haematological malignancies or postallogeneic haematopoietic stem cell transplant (HSCT) who received >/=1 dose of CAS as salvage monotherapy for IA as part of the Australian Special Access Scheme (4/2001-8/2002). Outcomes were assessed at the end of CAS therapy. Favourable response (FR) was defined as >50% clinical and radiological improvement. Risk factors for elevation of liver transaminases (LTs) were examined using multivariate models. 54 patients were included in the analysis with 47 neutropenic at study entry. Proven or probable IA occurred in 11 and refractory IA in 28. An FR occurred in 26 (48.1%) and predictors for a poor response to CAS were allogeneic HSCT, graft vs. host disease and treatment with CAS for <14 days. Concomitant CAS and CsA for >7 days was an independent risk factor for laboratory hepatoxicity. The CAS efficacy results from the Australian cohort confirm those of previous studies. Close monitoring of LTs is necessary on concomitant CAS and CsA but clinically relevant hepatotoxicity is rare.

Advances in the serological diagnosis of invasive Aspergillus infections in patients with haematological disorders

A reliable diagnosis of invasive aspergillosis in patients with haematological malignancies is seldom achieved antemortem. Conventional laboratory diagnostic methods are insensitive and time-consuming, resulting in late diagnosis and treatment and contributing to unacceptably high mortality. As a result, routine antifungal prophylaxis and early empirical treatment have been recommended. However, overtreatment associated with these strategies results in increased toxicity and cost. The use of sensitive and rapid non-culture-based diagnostic assays, such as detection of Aspergillus antigens (galactomannan, beta-D-glucan) or detection of genomic DNA sequences may allow a shift in emphasis from empirical to pre-emptive therapy, especially when substantiated by suggestive radiological findings. These new tools may be used to confirm a presumed diagnosis of invasive aspergillosis, or, when used to screen high-risk patients, may identify an infection at the early stage of disease. The excellent negative predictive value of these assays should convince clinicians to withhold antifungal therapy in persistently febrile neutropenic patients with no other signs of fungal infection. On the other hand, consecutive positive results in a high-risk population should at least trigger a complete diagnostic work-up. This review will focus on the diagnostic utility as well as on the pitfalls of serial screening for the presence of circulating fungal antigens in haematology patients.

Update on the contribution of galactomannan for the diagnosis of invasive aspergillosis

The diagnosis of invasive fungal infections (IFI) remains a challenge, particularly for diseases caused by filamentous fungi such as Aspergillus species. Unfortunately, many patients affected by these conditions are not identified before autopsy. Therefore, there is a need for new diagnostic methods for IFI. Galactomannan is a soluble antigen released during hyphal growth in tissues. A commercially available sandwich ELISA assay that detects galactomannan has been used in Europe for many years and is now approved for use in the USA. The test has an excellent negative predictive value in the detection of invasive aspergillosis (IA) in high-risk patients. In addition, it is more sensitive than culture and allows IA to be diagnosed before clinical manifestations occur. However, false-negative and false-positive results in certain populations are the main limitations to its use. The purpose of this review is to summarize the current knowledge about galactomannan testing in patients at risk for IA.

Preemptive antifungal therapy: still a way to go

PURPOSE OF REVIEW

Early treatment of invasive mold infections improves the outcome. Therapy is often delayed, however, because available diagnostic tools such as culture, microscopy and conventional radiology lack sensitivity; consequently, empirical initiation of antifungal therapy has been advocated, particularly for patients with prolonged unexplained neutropenic fever.

RECENT FINDINGS

Much recent progress has been made in the development and evaluation of nonculture-based assays, including the detection of the fungal antigens galactomannan and beta-D-glucan and the detection of fungal DNA by polymerase chain reaction techniques. These new tools should aid the rapid, early diagnosis of invasive fungal disease, especially when used as screening tools in conjunction with sensitive imaging techniques.

SUMMARY

The review will consider these recent developments with the purpose of introducing the concept of preemptive antifungal therapy.

Paradoxical Increase in CirculatingAspergillusAntigen during Treatment with Caspofungin in a Patient with Pulmonary Aspergillosis

A paradoxical increase in circulating Aspergillus antigen was observed during treatment with caspofungin in a patient with proven invasive aspergillosis. With the exception of treatment with the echinocandin, no other factors were found that might explain this clinical observation, which was supported by experiments done in vitro.

Clinical Issues Regarding Relapsing Aspergillosis and the Efficacy of Secondary Antifungal Prophylaxis in Patients with Hematological Malignancies

Advancements in early diagnosis and the introduction of effective agents have improved the rates of response of aspergillosis to primary antifungal therapy. These changes allow the subsequent continuation of cytotoxic chemotherapy and/or performance of hematopoietic stem cell transplantation in an increasing number of patients with hematological malignancies. These developments have increased interest in secondary prophylaxis of aspergillosis, because the resumption of myelotoxic chemotherapy in these patients is associated with high rates of relapse of this opportunistic mycosis in the absence of prophylaxis. However, the risk factors for relapsing invasive aspergillosis and the strategies for reducing risk are not well defined. Furthermore, differentiating aspergillosis relapse from reinfection with a new Aspergillus isolate is problematic when using the available laboratory tools. We summarize the existing knowledge regarding the pathogenesis of, risk factors for, and natural history of relapsing invasive aspergillosis and review the limited data regarding the role of secondary antifungal prophylaxis.

Impact of the intensity of the pretransplantation conditioning regimen in patients with prior invasive aspergillosis undergoing allogeneic hematopoietic stem cell transplantation: A retrospective survey of the Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation

In this retrospective study, we analyzed the outcomes of 129 patients who underwent an allogeneic hematopoietic stem cell transplantation (allo-HSCT) and had a history of probable or proven invasive aspergillosis (IA), of whom 57 (44%) received a reduced-intensity conditioning (RIC). Overall, 27 patients with IA progressed after the allo-HSCT (cumulative incidence [CumInc] at 2 years, 22%). The variables that increased the 2-year CumInc of IA progression were (1) longer duration of neutropenia after transplantation; (2) advanced status of the underlying disease; and (3) less than 6 weeks from start of systemic anti-Aspergillus therapy and the allo-HSCT. In addition, (4) conventional myeloablative conditioning increased the risk of progression early after transplantation (before day 30) only, while 3 variables increased the risk beyond day 30 were (5) cytomegalovirus disease; (6) bone marrow or cord blood as source of stem cells; and (7) grades II to IV acute graft-versus-host disease (GVHD). A risk model for progression was generated, defined as low (0-1 risk factors, 6% incidence), intermediate (2-3 risk factors, 27% incidence), or high risk (> or = 3 risk factors, 72% incidence [P < .001]). These findings may help in the interpretation and design of future studies on secondary prophylaxis of IA after an allo-HSCT.

Caspofungin: antifungal activity in vitro, pharmacokinetics, and effects on fungal load and animal survival in neutropenic rats with invasive pulmonary aspergillosis

OBJECTIVES

Evaluation of the potential of caspofungin, in relation to pharmacokinetics, in order to optimize its use in the treatment of filamentous fungal infections.

METHODS

The in vitro antifungal activity, pharmacokinetics and therapeutic efficacy of caspofungin versus amphotericin B was investigated in vitro as well as in a model of aerogenic Aspergillus fumigatus infection in neutropenic rats, using rat survival and decrease in fungal burden as parameters for therapeutic efficacy.

RESULTS

In contrast to amphotericin B, caspofungin shows a concentration-dependent gradual decrease in fungal growth in vitro, which makes it difficult to perform visual readings of antifungal activity (CLSI guidelines). The quantitative XTT [2,3-bis(2-methoxy-4-nitro-5-[(sulphenylamino) carbonyl]-2H-tetrazolium-hydroxide] assay measuring a decrease in fungal metabolic activity seems more appropriate for caspofungin susceptibility testing. Using this assay, in vitro caspofungin was 4-fold less active than amphotericin B. In the infection model, therapy was started 16 h after fungal inoculation, and continued once daily for 10 days. Caspofungin was administered intraperitoneally at 1, 2, 3 or 4 mg/kg/day (CAS 1, 2, 3 or 4), amphotericin B at 1 mg/kg/day (AMB 1). Treatment with CAS 1 or AMB 1 provided modest prolongation of animal survival. The combination of caspofungin and amphotericin B did not show additive effects. Increasing the dosage of caspofungin to 2, 3 or 4 mg/kg/day resulted in a dose-dependent significant increase in efficacy. There was 100% survival among rats in the CAS 4 group, which was correlated with a significant decrease in fungal burden, based on the concentration of A. fumigatus galactomannan in serum and lung tissue and quantification of A. fumigatus DNA in lung tissue. Pharmacokinetic analysis suggested that the CAS 4 dose in rats produced drug exposure comparable to the human situation, visualized by similar 24 h AUC and trough concentrations.

CONCLUSIONS

The therapeutic efficacy of caspofungin is superior to amphotericin B, which seemed to be discrepant with their in vitro antifungal activity.

Consensus definitions for invasive fungal disease: Strengths, limitations, and revisions

The European Organization for Research and Treatment of Cancer (EORTC)/ Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (MSG) consensus definitions for opportunistic invasive fungal infections have achieved their objective in fostering better communication between researchers but their limitations necessitated revision. In the last two years a group of experts drawn from both sides of the Atlantic have agreed a proposal for a new set of definitions that attempt to rectify omissions and problems arising from the original set whilst preserving their basic principles.