The contribution of galactomannan detection in the diagnosis of invasive aspergillosis in bone marrow transplant recipients

Until recently, accurate microbiological diagnosis of invasive aspergillosis (IA) was seldom established in HSCT recipients. Blood samples are rarely positive for Aspergillus species, the reliability of the cultures depends of the specimen (if taken from a normally sterile site or not) and biopsy samples require invasive procedures, rarely recommended in patients with severe thrombocytopenia. Implementing the international consensus defining the microbiological criteria for the diagnosis of Aspergillus infection, we retrospectively evaluated the role of serum galactomannan (GM) detection by EIA to diagnose IA among HSCT patients with proven invasive fungal infection (IFI) and the impact of serum storage in GM concentrations. The EIA assay allowed categorizing as “probable” 5 of the 10 cases of “possible” aspergillosis (50%). Considering a lower cut-off level for the reaction (1.0), 80% of the cases could be categorized as “probable” aspergillosis. Positive or undetermined results were detected one to 4 months before the diagnosis of IA in eight of the 11 patients (72.7%) with proven IFI. Retesting the stored samples after a second storage for four years, we could observe lower reactivity in 20% of the samples. The detection of galactomannan by the EIA test represents a major advance in the diagnosis of IA in HSCT recipients at high risk of IA. A better understanding of the kinetics of the GM in different clinical situations is necessary to maximize the benefit of the test in Aspergillus surveillance.     

Epidemiology of invasive fungal infection in solid organ transplant

Despite advances made in the last decades, invasive fungal infections (IFI) continue to be a major cause of morbidity and mortality in solid organ transplant recipients. The most common pathogens causing IFI are Candida species, followed by Aspergillus and Cryptococcus. A shift in the epidemiology of IFI has been reported in the last few years. Non-Candida albicans Candida species and non-Aspergillus filamentous moulds have been increasingly observed in transplant patients. A change in the IFI onset time has also been described recently. In the RESITRA (Spanish Network of Infection in Transplantation) study, at least 50% of invasive aspergillosis (IA) infections and 40% of invasive Candida infections had been observed after 180 days of transplant. Some cases of cryptococcal infection, traditionally considered as a late onset infection, have been observed in the early post transplant period. Mortality due to IFI is still high, particularly in patients with IA. However, the progressive improvement achieved in diagnosis and prevention of IFI has led to a lower mortality rate.     

Immunoproteomics based identification of thioredoxin reductase GliT and novel <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> antigens for serologic diagnosis of invasive aspergillosis

Background  

There has been a rising incidence of invasive aspergillosis (IA) in critically ill patients, even in the absence of an apparent predisposing immunodeficiency. The diagnosis of IA is difficult because clinical signs are not sensitive and specific, and serum galactomannan has relatively low sensitivity in this group of patients. Therefore, more prompt and accurate disease markers for early diagnosis are needed. To establish disease markers demands a thorough knowledge of fungal antigens which may be detected in the serum or other body fluids of patients. Herein we report novel immunodominant antigens identified from extracellular proteins of Aspergillus fumigatus.     

1–3 β-D-glucan: From Diagnosis to Prognosis

There are increasing numbers of patients at risk for invasive fungal infections (IFI). The early diagnosis of IFI’s is limited by the lack of sensitivity and delayed turn-around time of routine cultures. Delays in diagnosis are associated with poor outcomes, especially with immunocompromised hosts and patients within the intensive care unit (ICU). Over the last decade, fungal biomarkers such as galactomannan and 1,3-β-D-glucan (BDG) have been increasingly utilized for the early and accurate diagnosis of these infections. This review will evaluate the recent clinical data on the BDG assay, focusing on its ability to assist in the diagnosis of invasive candidiasis in the ICU, and also whether BDG kinetics can predict the prognosis of the patient. Similarly, this review will evaluate BDG in invasive Aspergillus and Pneumocystis jiroveci diagnosis and prognosis, as well as the current limitations of the assay.     

Diagnostic Values and Limitations of (1,3)-β-<Emphasis Type="SmallCaps">d</Emphasis>-Glucans and Galactomannan Assays for Invasive Fungal Infection in Patients Admitted to Pediatric Intensive Care Unit

The relationship among (1,3)-β-d-glucans (BG), galactomannan (GM), and the risk of developing invasive fungal infections (IFI) has been observed in adult ICU and in children with hematological malignancies. Only scant data evaluated the value of BG/GM assays for diagnosis of IFI in patients with nonhematological diseases in pediatric intensive care unit (PICU). In this study, we assessed the diagnostic value of these markers for IFI in PICU. The records of 230 patients were retrospectively evaluated. Out of 117 patients (7 proven, 23 probable, and 87 cases without evidence of IFI) performed GM and BG assays. The results showed many factors were associated with false-positive test results. Patients who aged over 3 years had higher levels of GM and BG than younger infants. The levels of BG were higher in subjects with dairy, human blood products, antibiotics, and corticosteroids therapy than in cases without these treatments. Unlike BG assay, GM assay was less susceptible to above-mentioned factors expect blood products. The levels of BG and GM in IFI cases were dramatically higher than in controls. The diagnostic performance of these assays showed that GM assay had better results when compared with BG assay. On the whole, negative predictive value in both GM and BG assays was dramatically higher than other diagnostic parameters. In conclusion, BG assay was highly susceptible to many factors, and GM assay could be useful for diagnosis of IFI for its high sensitivity, but the over benefit of this assay limited in its inadequate specificity. The comparative advantage of BG and BG assays lied in excluding IFI in non-hematological PICU patients.     

Diagnosis of invasive fungal disease in hospitalized patients with chronic obstructive pulmonary disease

Background

The role of culture-independent techniques (galactomannan, (1-3)-β-d-glucan) in the early diagnosis of invasive fungal diseases (IFD) is well assessed in hematological patients, but there are no clear conclusions in patients with chronic obstructive pulmonary disease (COPD).

Diagnostic Performance of an Aspergillus-Specific Nested PCR Assay in Cerebrospinal Fluid Samples of Immunocompromised Patients for Detection of Central Nervous System Aspergillosis

Central nervous system (CNS) invasive aspergillosis (IA) is a fatal complication in immunocompromised patients. Confirming the diagnosis is rarely accomplished as invasive procedures are impaired by neutropenia and low platelet count. Cerebrospinal fluid (CSF) cultures or galactomannan (GM) regularly yield negative results thus suggesting the need for improving diagnostic procedures. Therefore the performance of an established Aspergillus-specific nested polymerase chain reaction assay (PCR) in CSF samples of immunocompromised patients with suspicion of CNS IA was evaluated. We identified 113 CSF samples from 55 immunocompromised patients for whom CNS aspergillosis was suspected. Of these patients 8/55 were identified as having proven/probable CNS IA while the remaining 47 patients were classified as having either possible (n = 22) or no CNS IA (n = 25). PCR positivity in CSF was observed for 8/8 proven/probable, in 4/22 possible CNS IA patients and in 2/25 NoIA patients yielding sensitivity and specificity values of 1.0 (95% CI 0.68–1) and 0.93 (95% CI 0.77–0.98) and a positive likelihood ratio of 14 and negative likelihood ratio of 0.0, respectively, thus resulting in a diagnostic odds ratio of ∞. The retrospective analysis of CSF samples from patients with suspected CNS IA yielded a high sensitivity of the nested PCR assay. PCR testing of CSF samples is recommended for patients for whom CNS IA is suspected, especially for those whose clinical condition does not allow invasive procedures as a positive PCR result makes the presence of CNS IA in that patient population highly likely.     

Diagnóstico microbiológico de las micosis invasoras

The prognosis of invasive fungal infections (IFI) depends on the speed of diagnosis and treatment. Conventional diagnostic methods are of low sensitivity, laborious and too slow, leading to the need for new, faster, and more efficient diagnostic strategies.There are several techniques for diagnosing a candidemia that are faster than the conventional blood culture (BC). Once yeast growth in BC is detected, species identification can be speeded up by mass spectrometry (30 minutes), commercialised molecular techniques (60-80 minutes) or fluorescent in situ hybridization (90 minutes). The combined detection of biomarkers (antimicellium, mannan and anti-mannan or β-glucan) has shown to be of greater use than their individual use. Commercialised nucleic acid amplification techniques (Septifast®, T2Candida®) are very reliable alternatives to BC. The detection of the capsular antigen of Cryptococcus, by means of latex agglutination or immuno-chromatography, is a valuable technique for cryptococcosis diagnosis.Direct microscopic examination and culture of representative specimens is used for the conventional diagnosis of IFI by filamentous fungi. Detection of galactomannan and β-glucan are considered diagnostic criteria for probable invasive aspergillosis and probable IFI, respectively, despite the lack of specificity of the latter. The detection of fungal volatile organic compounds in breath is an interesting diagnostic strategy in pulmonary infections. Although widely used, nucleic acid detection techniques are not considered diagnostic criteria for IFIs caused by moulds in consensus documents, due to their lack of standardisation. However, they are the only alternative to culture methods in invasive infections by Scedosporium/Lomentospora, Fusarium, zygomycetes, or dematiaceous fungi.     

Prevention of invasive aspergillosis in high-risk patients: Universal versus preemptive, targeted treatment

Invasive aspergillosis (IA) is associated with increased morbidity and mortality, and there is a need for better preventative and therapeutic approaches. Successful treatment of documented IA remains difficult, often because of the inability to detect disease at an early stage. An important, recent advance in the management of aspergillosis is the availability of the newer broad-spectrum azoles, voriconazole and posaconazole, which have good activity against Aspergillus spp. In addition, newer diagnostic modalities including Aspergillus galactomannan, β-glucan, and polymerase chain reaction are more readily available. These diagnostic and treatment options have made new strategies possible for the management of IA. Prophylaxis and empirical therapy for high-risk patients have been popular for decades, and now a preemptive, targeted approach to IA management has become more attractive. This article reviews strategies for the prevention and management of IA and compares and contrasts universal prophylaxis to the preemptive, targeted approach for IA in high-risk patients.     

Usefulness of the Serum Galactomannan Assay for Early Response Assessment and Treatment Stratifications of Invasive Aspergillosis

The galactomannan (GM) Enzyme Immunoassay (EIA) is an upcoming tool not only for diagnosis but also monitoring of invasive Aspergillosis (IA). Various studies were performed over the last years to apply such a promising instrument correctly. New findings show the potential of this test to segregate affected patients into treatment responders and non-responders at a time point as early as 7–14 days after initiation of antifungal therapy. Current data suggest that serial GM testing in patients receiving antifungal therapy for IA is essential as GMI kinetics may offer the clinician a substantial support in decision making concerning early therapeutic stratifications. The correct interpretation of GM EIA results with respect to the individual context of the patient is, however, absolutely necessary. The following review shall give an overview about the GM-EIA as a tool for IA monitoring and therapy stratification.     

The Performance of Real-Time PCR, Galactomannan, and Fungal Culture in the Diagnosis of Invasive Aspergillosis in Ventilated Patients with Chronic Obstructive Pulmonary Disease (COPD)

Emerging reports have associated chronic pulmonary obstructive disease (COPD) with invasive aspergillosis (IA), particularly in patients treated with mechanical ventilation and/or corticosteroids. This is a multicentre study in which COPD patients demonstrating a new lung infiltrate while being mechanically ventilated were prospectively evaluated for the presence of IA. From the 47 patients studied, Aspergillus fumigatus was recovered in culture in two patients (4.2%). While serum galactomannan (GM) was negative for 94% of patients, GM levels in respiratory samples were >0.5, >1.0 and >1.5 for 74.5, 40.5, and 21.3% of patients, respectively. PCR was positive for 10 patients in the study but did not differentiate Aspergillus colonization from infection. The combination of PCR and GM in respiratory samples may be an interesting alternative to diagnose IA in COPD patients.     

Aspergilosis invasora en el receptor de trasplante de órgano sólido

Solid organ transplant (SOT) recipients have a high risk for developing invasive fungal infections (IFI). Treatment is difficult due to the interaction between the antifungal and immunosuppressant drugs, as well as the risk of hepatotoxicity and kidney failure associated with voriconazole and amphotericin B, respectively. Isavuconazole is a new antifungal triazole agent with excellent oral bioavailability, predictable and linear pharmacokinetics, good tolerance and low adverse effects. It has been approved for the treatment of invasive aspergillosis and mucormycosis.A review is presented of the reported experience in the use of isavuconazole in SOT. According to the published studies, isavuconazole has a significantly lower risk of interaction with tacrolimus, and is less hepatotoxic than voriconazole. Nevertheless, there is a significant variability between patients, and between each type of SOT.Isavuconazole reduces the side effects associated with the treatment of IFI in SOT. It would be of great interest the implementation of future clinical trials with isavuconazole for the treatment and/or prophylaxis of IFI in these patients.     

Early diagnosis of invasive aspergillosis in neutropenic patients with bi-weekly serial screening of circulating galactomannan by Platelia Aspergillus

The diagnosis of invasive aspergillosis in neutropenic individuals is difficult and lengthy since non-invasive diagnostic tests lack sensitivity and specificity. The diagnosis of invasive aspergillosis in 154 prolonged neutropenic patients was prospectively bi-weekly validated by screening circulating galactomannan. The global sensitivity was 73% and specificity was 96%. The positive and negative predictive values were 73% and 98% respectively. False positive reactions occurred at a rate of 2%. Antigenemia was detected before clinical suspicion of invasive aspergillosis (median, 6 days before) in 30% of patients and anticipated the onset of radiologic signs 9 days in 60% of patients. CONCLUSION: the prospective screening of galactomannan is a sensitive and non-invasive tool for early diagnosis of invasive aspergillosis in high-risk adult hematology patients.     

An Approach to Suspected Invasive Fungal Infection in Patients with Hematologic Malignancy and HCT Recipients with Persistent Neutropenic Fever Despite Mold-Active Prophylaxis

Purpose of Review

This review offers an approach to managing suspected invasive fungal infection (IFI) in a febrile neutropenic patient with hematologic malignancy or hematopoietic cell transplantation (HCT) while on mold-active prophylaxis. We take into consideration host characteristics, new diagnostic tools, and available therapeutics.

Recent Findings

Despite use of anti-Aspergillus prophylactic agents, invasive aspergillosis is the most commonly reported IFI breaking through common prophylactic agents including the newest azole, isavuconazole. While more fungal diagnostic modalities are available, how to best incorporate them in the work-up of IFI remains unclear, while sensitivity of any particular fungal biomarker or molecular test is low.

Summary

In a febrile neutropenic patient with hematologic malignancy or HCT and suspected IFI, consider particularly invasive aspergillosis, regardless of the mold-active prophylactic agent. Early diagnosis and intervention are especially important to a favorable outcome; treatment is directed based on the suspected IFI syndrome and suspected organism. Switching azoles, consideration of combination therapy, and reducing immunosuppression are proposed strategies for the management of breakthrough IFI, while surgical debridement remains crucial for Mucormycoses. More study is needed into the optimal antifungal approach in these clinical scenarios. Meanwhile, therapeutic drug monitoring and attention to drug-drug interactions are encouraged.

     

Aspergilosis invasiva en el paciente crítico

Critically ill patients without severe immunosuppression make up a population in which invasive aspergillosis (IA) has been identified as an emergent pathology. Chronic treatment with corticosteroids, chronic obstructive pulmonary disease, and liver cirrhosis are repeatedly identified risk factors. However, due to the non-specificity of the symptoms and signs in the critical patient, and the relative low diagnostic capacity of the complementary tests, the diagnosis of the IA is a challenge for the specialist in critical care medicine. The application of diagnostic algorithms adapted to critical patients, in whom activation will depend on the isolation of Aspergillus in a respiratory specimen, is the most efficient diagnostic methodology in this population. Among the diagnostic approaches, the determination of galactomannan in bronchoalveolar fluid is the most useful diagnostic test. Once the suspicion is established, treatment should be started as soon as possible. Voriconazole, amphotericin B, and isavuconazole are the most effective treatments. Although voriconazole and amphotericin B are the drugs with the most scientific evidence, they are related with adverse effects and pharmacokinetic difficulties. Therefore, isavuconazole, which has shown high efficacy and safety in other populations, is a potential alternative of great interest for critically ill patients.     

Value of Aspergillus galactomannan antigen detection in the diagnosis and follow-up of invasive aspergillosis in hematological patients

Serum galactomannan detection is considered to be a useful test for early diagnosis and follow-up of invasive aspergillosis. From February to September 2002, adult patients hospitalized in our Hematology Unit for receiving intensive chemotherapy and/or hematopoietic stem cell transplant were prospectively studied. We analyzed a total of 760 samples obtained from 100 patients. Eleven patients (11%) having a positive result (OD index >1.5 ng/ml) in two consecutive Platelia Aspergillus tests were considered galactomannan-positive cases. On the other hand, 12 patients (12%) were diagnosed of proven or probable invasive aspergillosis. Sensitivity (66.6%), specificity (95.5%), positive predictive value (72.7%) and negative predictive value (96.7%) were comparable to those of larger series. Galactomannan positivity allowed also to anticipate invasive aspergillosis diagnosis (from two to 17 days before radiographic findings and from two to 15 days before mycological culture). Moreover, kinetics of antigenemia could be useful for assessing therapeutic response. Once accepted galactomannan test as a diagnostic criterium for invasive aspergillosis knowing potential causes of false positive results is of paramount importance.     

Tratamiento antifúngico individualizado en el paciente crítico con infección fúngica invasora

Invasive candidiasis (IC) is the most common invasive fungal infection (IFI) affecting critically ill patients, followed by invasive pulmonary aspergillosis (IPA). International guidelines provide different recommendations for a first-line antifungal therapy and, in most of them, echinocandins are considered the first-line treatment for IC, and triazoles are so for the treatment of IPA. However, liposomal amphotericin B (L-AmB) is still considered a second-line therapy for both clinical entities. Although in the last decade the management of IFI has improved, several controversies persist. The antifungal drugs currently available may have a suboptimal activity, or be wrongly used in certain IFI involving critically ill patients. The aim of this review is to analyze when to provide individualized antifungal therapy to critically ill patients suffering from IFI, emphasizing the role of L-AmB. Drug-drug interactions, the clinical status, infectious foci (peritoneal candidiasis is discussed), the fungal species involved, and the need of monitoring the concentration of the antifungal drug in the patient are considered.     

Low Rate of Invasive Fungal Infections During Induction and Consolidation Chemotherapy for Adults with De Novo Acute Myeloid Leukemia Without Anti-mold Prophylaxis: Single-Center 2002–2018 Empirical/Pre-emptive Approach

Broad-spectrum antifungal prophylaxis is currently considered the standard of care for adults with de novo AML for the prevention of invasive fungal infections (IFIs), especially invasive pulmonary aspergillosis (IPA). Because fluconazole has been used in our center as anti-yeast prophylaxis, we sought to analyze in detail the incidence of IFIs over a 17-year period, as well as their impact on outcome. A standardized protocol of patient management, including serum galactomannan screening and thoracic CT-guided diagnostic-driven antifungal therapy, was used in all patients. A total of 214 consecutive adults with de novo AML who were treated in 3 CETLAM (Grupo Cooperativo para el Estudio y Tratamiento de las Leucemias Agudas y Mielodisplasias) protocols from 2002 to 2018 were included. The 90-day incidence of any IFI (including possible cases) was 11% (95% CI 4–15%), most cases occurred during induction chemotherapy (8%, 95% CI 4–12%), and most cases were probable/proven IPA (8%, 95% CI 3–13%). Developing an IFI during induction and consolidation had no impact on 1-year survival. A case–control study with 23 cases of IPA and 69 controls identified induction/re-induction chemotherapy, chronic pulmonary disease and age?>?60 years/poor baseline performance status as potential pretreatment risk factors. The current study proves that inpatient induction and consolidation chemotherapy for de novo AML can be given in areas with “a priori” high-burden of airborne molds with fluconazole prophylaxis, while the selective use of anti-mold prophylaxis in patients at very high risk may further reduce the incidence of IFI in this specific clinical scenario.

     

Usefulness of galactomannan detection in the diagnosis and follow-up of hematological patients with invasive aspergillosis

The usefulness of galactomannan detection using the Platelia Aspergillus test for the diagnosis of invasive aspergillosis was studied in 849 sera from 54 hematological patients with prolonged neutropenia, which were classified according to the risk for invasive aspergillosis. Three patients developed a proven invasive aspergillosis, one a probable invasive aspergillosis and 17 patients a possible invasive aspergillosis. Thirty-three patients showed no evidence of invasive aspergillosis. All patients with proven invasive aspergillosis had a high risk for invasive aspergillosis, while the one having probable invasive aspergillosis had intermediate risk. Detection of galactomannan in this study showed a sensitivity of 66.7% for patients with proven invasive aspergillosis and 50% for patients with proven and probable invasive aspergillosis. The specificity was 98% or higher in all groups studied. The predictive positive and negative values for patients with proven invasive aspergillosis were 66.7% and 98%, respectively. A rise in the concentration of galactomannan was observed in patients who failed to respond to the antifungal treatment. Galactomannan antigenemia preceded post-mortem histological diagnosis of invasive aspergillosis in two patients by 17 and 81 days, respectively. In conclusion, detection of galactomannan by the Platelia Aspergillus test allows for a specific and relatively sensitive diagnosis of invasive aspergillosis in hematological patients with a high and intermediate risk for invasive aspergillosis.     

The Role of Biomarkers for Diagnosis of and Therapeutic Decisions Related to Invasive Aspergillosis in Children

Invasive aspergillosis (IA) is a feared opportunistic infection for many immuncompromised children resulting in significant morbidity and mortality. Timely diagnosis based on traditional testing modalities and clinical evaluation has proven to be challenging. Assays designed to measure IA biomarkers such as galactomannan (GM) and beta-D-glucan (BG) represent a potential significant improvement in the ability to diagnose pediatric IA. However, as with any new diagnostic tool, clinicians need to be aware of the operating characteristics of these assays in order to apply them in the appropriate settings. Published adult and pediatric data regarding GM and BG testing are reviewed and guidance regarding the appropriate utility of these assays in children is offered.