What should be the optimal cut-off of serum 1,3-β-D-glucan for the detection of invasive pulmonary aspergillosis in patients with haematological malignancies?

Comparison of β-D-Glucan and Galactomannan in Serum for Detection of Invasive Aspergillosis: Retrospective Analysis with Focus on Early Diagnosis

The early diagnosis of invasive aspergillosis (IA) relies mainly on computed tomography imaging and testing for fungal biomarkers such as galactomannan (GM). We compared an established ELISA for the detection of GM with a turbidimetric assay for detection of the panfungal biomarker β-D-glucan (BDG) for early diagnosis of IA. A total of 226 serum specimens from 47 proven and seven probable IA cases were analysed. Sensitivity was calculated for samples obtained closest to the day of IA-diagnosis (d0). Additional analyses were performed by including samples obtained during the presumed course of disease. Most IA cases involved the respiratory system (63%), and Aspergillus fumigatus was the most frequently isolated species (59%). For proven cases, sensitivity of BDG/GM analysis was 57%/40%. Including all samples dating from –6 to +1 weeks from d0 increased sensitivities to 74%/51%. Sensitivity of BDG testing was as high as or higher than GM testing for all subgroups and time intervals analysed. BDG testing was less specific (90–93%) than GM testing (99–100%). Combining BDG and GM testing resulted in sensitivity/specificity of 70%/91%. Often, BDG testing was positive before GM testing. Our study backs the use of BDG for diagnosis of suspected IA. We suggest combining BDG and GM to improve the overall sensitivity.

(1→3)-β-D-glucan testing for the detection of invasive fungal infections in immunocompromised or critically ill people

BACKGROUND

Invasive fungal infections (IFIs) are life-threatening opportunistic infections that occur in immunocompromised or critically ill people. Early detection and treatment of IFIs is essential to reduce morbidity and mortality in these populations. (1→3)-β-D-glucan (BDG) is a component of the fungal cell wall that can be detected in the serum of infected individuals. The serum BDG test is a way to quickly detect these infections and initiate treatment before they become life-threatening. Five different versions of the BDG test are commercially available: Fungitell, Glucatell, Wako, Fungitec-G, and Dynamiker Fungus.

OBJECTIVES

To compare the diagnostic accuracy of commercially available tests for serum BDG to detect selected invasive fungal infections (IFIs) among immunocompromised or critically ill people.

SEARCH METHODS

We searched MEDLINE (via Ovid) and Embase (via Ovid) up to 26 June 2019. We used SCOPUS to perform a forward and backward citation search of relevant articles. We placed no restriction on language or study design.

SELECTION CRITERIA

We included all references published on or after 1995, which is when the first commercial BDG assays became available. We considered published, peer-reviewed studies on the diagnostic test accuracy of BDG for diagnosis of fungal infections in immunocompromised people or people in intensive care that used the European Organization for Research and Treatment of Cancer (EORTC) criteria or equivalent as a reference standard. We considered all study designs (case-control, prospective consecutive cohort, and retrospective cohort studies). We excluded case studies and studies with fewer than ten participants. We also excluded animal and laboratory studies. We excluded meeting abstracts because they provided insufficient information.

DATA COLLECTION AND ANALYSIS

We followed the standard procedures outlined in the Cochrane Handbook for Diagnostic Test Accuracy Reviews. Two review authors independently screened studies, extracted data, and performed a quality assessment for each study. For each study, we created a 2 × 2 matrix and calculated sensitivity and specificity, as well as a 95% confidence interval (CI). We evaluated the quality of included studies using the Quality Assessment of Studies of Diagnostic Accuracy-Revised (QUADAS-2). We were unable to perform a meta-analysis due to considerable variation between studies, with the exception of Candida, so we have provided descriptive statistics such as receiver operating characteristics (ROCs) and forest plots by test brand to show variation in study results.

MAIN RESULTS

We included in the review 49 studies with a total of 6244 participants. About half of these studies (24/49; 49%) were conducted with people who had cancer or hematologic malignancies. Most studies (36/49; 73%) focused on the Fungitell BDG test. This was followed by Glucatell (5 studies; 10%), Wako (3 studies; 6%), Fungitec-G (3 studies; 6%), and Dynamiker (2 studies; 4%). About three-quarters of studies (79%) utilized either a prospective or a retrospective consecutive study design; the remainder used a case-control design. Based on the manufacturer's recommended cut-off levels for the Fungitell test, sensitivity ranged from 27% to 100%, and specificity from 0% to 100%. For the Glucatell assay, sensitivity ranged from 50% to 92%, and specificity ranged from 41% to 94%. Limited studies have used the Dynamiker, Wako, and Fungitec-G assays, but individual sensitivities and specificities ranged from 50% to 88%, and from 60% to 100%, respectively. Results show considerable differences between studies, even by manufacturer, which prevented a formal meta-analysis. Most studies (32/49; 65%) had no reported high risk of bias in any of the QUADAS-2 domains. The QUADAS-2 domains that had higher risk of bias included participant selection and flow and timing.

AUTHORS' CONCLUSIONS

We noted considerable heterogeneity between studies, and these differences precluded a formal meta-analysis. Because of wide variation in the results, it is not possible to estimate the diagnostic accuracy of the BDG test in specific settings. Future studies estimating the accuracy of BDG tests should be linked to the way the test is used in clinical practice and should clearly describe the sampling protocol and the relationship of time of testing to time of diagnosis.

Diagnostic Accuracy of β-d-Glucan (Fungitell) Testing Among Patients With Hematologic Malignancies or Solid Organ Tumors: A Systematic Review and Meta-Analysis

Objectives

To determine the accuracy of Fungitell, a β-d-glucan (BDG) test, for the diagnosis of invasive fungal infection (IFI) among cancer patients.

Methods

For this meta-analysis, MEDLINE and EMBASE were searched for references related to BDG testing. Study quality was evaluated using QUADAS-2. Statistical analysis was performed using Stata 14.

Results

We screened 12,426 references and identified 189 studies for full-text review. Nineteen studies were included in the final meta-analysis. There was moderate heterogeneity between studies. Nine studies had a high risk of bias, which significantly elevated the overall specificity estimate. Restricting to only low-bias studies, the sensitivity and specificity were 80% and 63%, respectively.

Conclusions

The overall sensitivity and specificity of Fungitell as a diagnostic test for IFI is moderate, and there is substantial heterogeneity between studies. Limiting studies to only low-bias risk reduced heterogeneity but also lowered the overall specificity estimate.

Diagnostic Efficacy of Serum 1,3-β-D-glucan for Invasive Fungal Infection: An Update Meta-Analysis Based on 37 Case Or Cohort Studies

Objective

The aim of this study was to investigate the diagnostic performance of serum 1,3-β-D-gluan as biomarker for invasive fungal infection through meta-analysis.

Methods

The electronic databases of Medline, Cochrane, Embase, Web of Science, OVID and CNKI were systematic searched to identified the case-control or Cohort studies relevant to diagnostic efficacy of serum 1,3-β-D-glucan for invasive fungal infection. The data of true positive (tp), false positive (fp), false negative (fn) and true negative (tn) patients number were extracted from each of the original included studies. The diagnostic sensitivity, specificity and systematic receiver operating characteristic (SROC) curve were calculated and pooled through random or fixed effect method. The publication bias was evaluated by the Deek's funnel plot.

Results

Thirty-seven relevant studies were fulfilled the inclusion criteria and included in our present meta-analysis. The combined sensitivity, specificity, positive likely hood ratio (+lr), negative likely hood ratio (-lr) and diagnostic odds ratio(dor) for 1,3-β-D-glucan in diagnosis of invasive fungal infectionwere 0.83 (95%CI:0.38-0.61), 0.81 (95%CI:0.80-0.82), 5.13 (95%CI:3.98-6.62), 0.23 (95%CI:0.18-0.30), and 29.68 (95%CI:18.94-46.52) respectively. The pooled area under the ROC curve (AUC) was 0.91.The Deek's funnel plot asymmetry test showed there was no publication bias for 1,3-β-D-glucan in diagnosis of invasive fungal infection of the included 37 studies.

Conclusion

Serum 1,3-β-D-glucan assay was a promising biomarker for invasive fungal infection diagnosis.

Diagnostic value of serum galactomannan, (1,3)-β-d-glucan, and Aspergillus fumigatus-specific IgA and IgG assays for invasive pulmonary aspergillosis in non-neutropenic patients

Detection of serum galactomannan (GM) and (1,3)-β-d-glucan (BG) is considered useful for non-culture diagnosis of invasive pulmonary aspergillosis (IPA) in neutropenic patients. Only few studies evaluated these seromarkers in non-neutropenic patients suspected of having IPA. The aim of this study was to evaluate both tests together with the Aspergillus fumigatus-specific serum IgG and IgA (IgAG) test for serological IPA diagnosis in non-neutropenic patients. Sera from 87 patients suspected of having IPA were retrospectively analysed. Patients were categorised into groups of proven IPA (n = 10), putative IPA (n = 31) and non-IPA colonisation (n = 46). When the GM, BG and IgAG assays were used for patients included in the study, the sensitivity/specificity/positive predictive value (PPV)/negative predictive value (NPV) were 48.8%/91.3%/83.3%/66.7%, 82.9%/73.9%/73.9%/82.9% and 75.6%/95.7%/93.9%/81.5%, respectively. Thus, the highest specificity and PPV were confirmed for the IgAG assay. Improvements in the sensitivity and NPV were achieved by "at least one positive" analysis with the GM and BG assays, with the sensitivity/specificity/PPV/NPV values being 85.0%/69.6%/71.4%/84.2%. Nevertheless, the highest sensitivity and NPV were achieved by the "at least one positive" analysis combining the GM, BG and IgAG tests (97.6% and 96.8%, respectively). The involvement of the IgAG assay could improve IPA diagnosis in non-neutropenic patients by increasing the sensitivity and NPV when combined with the GM or BG assays. Furthermore, improvement was achieved by combining the GM, BG and IgAG assays using the "at least one positive test" strategy, especially if doubt exists.

Invasive pulmonary aspergillosis secondary to microwave ablation: a multicenter retrospective study

PURPOSE

Invasive pulmonary aspergillosis (IPA) is a life-threatening complication of microwave ablation (MWA) during the treatment of primary or metastatic lung tumors. The purpose of this study was to investigate the clinical, radiological and demographic characteristics and treatment responses of patients with IPA after MWA.

MATERIALS AND METHODS

From January 2011 to January 2016, all patients who were treated by MWA of their lung tumors from six health institutions were enrolled in this study. Patients with IPA secondary to MWA were identified and retrospectively evaluated for predisposing factors, clinical treatment, and outcome.

RESULTS

The incidence of IPA secondary to lung MWA was 1.44% (23/1596). Of the 23 patients who developed IPA, six died as a consequence, resulting in a high mortality rate of 26.1%. Using computed tomography (CT), pulmonary cavitation was the most common finding and occurred in 87.0% (20/23) of the patients. Sudden massive hemoptysis was responsible for one-third of the deaths (2/6). Most patients (22/23) received voriconazole as an initial treatment, and six patients with huge cavities underwent intracavitary lavage. Finally, 17 patients (73.9%) achieved treatment success.

CONCLUSIONS

Lung MWA may be an additional host risk factor for IPA, particularly in elderly patients with underlying diseases and in patients who have recently undergone chemotherapy. Early and accurate diagnosis of IPA after MWA is critical for patient prognosis. Voriconazole should be given as the first-line treatment as early as possible. Bronchial artery embolization or intracavitary lavage may be required in some patients.

Use of 1,3-β-D-glucan in invasive fungal diseases in hematology patients

INTRODUCTION

Invasive fungal diseases (IFD) remain a leading cause of morbidity and mortality in hematology patients. Within a diagnostic-driven approach, the use of the serum (1,3)-ß-D-glucan (BDG) test represents a valid tool for the early diagnosis and treatment of IFD. Areas covered: The available literature on the use of BDG in hematology patients was systematically retrieved. Then, it was reviewed and discussed, to identify key issues pertaining to a clinically-oriented narrative presentation of the topic. Expert commentary: The use of BDG in hematology patients at risk for invasive aspergillosis (IA) is secondary to the use of galactomannan. However, since BDG is not specific for IA, it offers an advantage of diagnosing also other IFD, such as candidiasis and pneumocystosis. The limitations of BDG include high costs and lower sensitivity in hematology patients compared to other cohorts. The risk of false positive results is possibly lower in real life than in theory, since glucan-free equipment is available and modern dialysis membranes and blood products usually do not release BDG. Thus, in experienced hands and selected clinical situations, BDG is a useful diagnostic tool, particularly due to short turnover time to results and versatility in diagnosing different IFD.

Comparison of galactomannan, beta-D-glucan, and Aspergillus DNA in sera of high-risk adult patients with hematological malignancies for the diagnosis of invasive aspergillosis

BACKGROUND/AIM

Invasive aspergillosis (IA) is a fatal infection that is difficult to diagnose in immunocompromised patients. In this study, Aspergillus-specific DNA was searched using real-time PCR (RT-PCR) in serum samples. Galactomannan (GM) and/or beta-D-glucan (BDG) tests were previously performed on these samples for 70 neutropenic patients with hematological malignancy.

MATERIALS AND METHODS

The patients were categorized according to the criteria of the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG). Among the patient serum samples, the first positive GM or BDG test sample and the median sample of GM or BDG test for negative patients were used to detect DNA levels by RT-PCR method (Light Cycler 480, Roche Molecular Biochemicals, Meylan, France) using a commercial kit (Way2Gene Fungi; Genmar, İzmir, Turkey).

RESULTS

When the proven and probable IA group were considered as real patients, sensitivity of Aspergillus-specific DNA test was 90%, specificity was 73.3%, positive predictive value was 81.8%, and negative predictive value was 84.6%.

CONCLUSION

This study found that searching for specific DNA by RT-PCR method has a sensitivity as high as the GM test. Although specificity was rather low, it was concluded that it can be used jointly with GM and BDG tests after decreasing contamination by severe laboratory applications.

Aspergillus Polymerase Chain Reaction: Systematic Review of Evidence for Clinical Use in Comparison With Antigen Testing

BACKGROUND

Aspergillus polymerase chain reaction (PCR) was excluded from the European Organisation for the Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) definitions of invasive fungal disease because of limited standardization and validation. The definitions are being revised.

METHODS

A systematic literature review was performed to identify analytical and clinical information available on inclusion of galactomannan enzyme immunoassay (GM-EIA) (2002) and β-d-glucan (2008), providing a minimal threshold when considering PCR. Categorical parameters and statistical performance were compared.

RESULTS

When incorporated, GM-EIA and β-d-glucan sensitivities and specificities for diagnosing invasive aspergillosis were 81.6% and 91.6%, and 76.9% and 89.4%, respectively. Aspergillus PCR has similar sensitivity and specificity (76.8%-88.0% and 75.0%-94.5%, respectively) and comparable utility. Methodological recommendations and commercial PCR assays assist standardization. Although all tests have limitations, currently, PCR is the only test with independent quality control.

CONCLUSIONS

We propose that there is sufficient evidence that is at least equivalent to that used to include GM-EIA and β-d-glucan testing, and that PCR is now mature enough for inclusion in the EORTC/MSG definitions.

Molecular and nonmolecular diagnostic methods for invasive fungal infections

Invasive fungal infections constitute a serious threat to an ever-growing population of immunocompromised individuals and other individuals at risk. Traditional diagnostic methods, such as histopathology and culture, which are still considered the gold standards, have low sensitivity, which underscores the need for the development of new means of detecting fungal infectious agents. Indeed, novel serologic and molecular techniques have been developed and are currently under clinical evaluation. Tests like the galactomannan antigen test for aspergillosis and the β-glucan test for invasive Candida spp. and molds, as well as other antigen and antibody tests, for Cryptococcus spp., Pneumocystis spp., and dimorphic fungi, have already been established as important diagnostic approaches and are implemented in routine clinical practice. On the other hand, PCR and other molecular approaches, such as matrix-assisted laser desorption ionization (MALDI) and fluorescence in situ hybridization (FISH), have proved promising in clinical trials but still need to undergo standardization before their clinical use can become widespread. The purpose of this review is to highlight the different diagnostic approaches that are currently utilized or under development for invasive fungal infections and to identify their performance characteristics and the challenges associated with their use.

A Single Center Experience for Antifungal Prophylaxis in Patients with Acute Myelogenous Leukemia

We aimed to provide real-life information about the effectivity of different types of primary antifungal prophylaxis (AFP) in patients with acute myeloid leukemia (AML). Records of AML patients who received remission-induction chemotherapy between June 2010 and February 2013 were retrospectively reviewed. A total of 85 AML remission-induction chemotherapy cycles were identified in 80 patients. Fluconazole prophylaxis (FP) was administered in 29 cycles, and posaconazole prophylaxis was given in 56 cycles. Failure in the AFP was observed in 45 (57.9 %) out of 85 cycles. Any type of invasive fungal diseases were detected in 15 (26.8 %) out of 56 cycles receiving posaconazole and 15 (51.7 %) out of 29 cycles receiving fluconazole (p = 0.023). Relapsing or refractory AML, longer duration of neutropenia and FP were more common in patients with AFP failure. Multivariate logistic regression analysis showed that type of AFP (odds ratio (OR) 3.63; 95 % confidence interval (CI) 1.19-11.07), presence of neutropenia longer than 21 days (OR 3.96; 95 % CI 1.36-11.46), and refractory or relapsing AML (OR 6.09; 95 % CI 2.09-17.73) were independent factors associated with failure of AFP. We observed superiority of posaconazole on fluconazole in the prophylaxis of AML patients receiving remission-induction chemotherapy.

Routine Use of a Protease Zymogen-Based Colorimetric Assay for the Detection of Beta-Glucan and its Role in Clinical Practice

The detection of Aspergillus antigen (galactomannan) is considered a reliable marker for the diagnosis of invasive aspergillosis (IA), yet the sensibility and specificity of the assays commonly employed in routine are not optimal. The aim of the present study was to investigate whether the detection of another panfungal antigen, the (1,3)-b-D-glucan could have an auxiliary role in the identification of patients with IA. The study was carried out on 63 sera belonging to patients who had been screened for galactomannan, according to the clinical suspect of IA. Our data show that the positive galactomannan results were not confirmed by positive (1,3)-b-D-glucan results in patients receiving therapy with beta-lactam antibiotics associated with tazobactam, whereas in all the other cases, with the exception of four, the results of the (1,3)-b-D-glucan test were confirmatory of the galactomannan results.

Diagnostic value of the serum galactomannan and (1, 3)-β-D-glucan assays for invasive pulmonary aspergillosis in non-neutropenic patients

OBJECTIVE

Galactomannan (GM) and (1, 3)-β-D-glucan (BG) are considered useful seromarkers for the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with neutropenia. However, there is still limited data on these seromarkers for testing non-neutropenic patients who are at the risk of IPA. The aim of this study was to evaluate the value of these two serum antigen assays for the early diagnosis of IPA in patients without neutropenia.

METHODS

Between January 2011 and December 2012, 97 patients with suspected IPA admitted to the department of respiratory diseases and the respiratory intensive care unit were prospectively monitored. Serum GM and BG assays were performed before the patients received antifungal therapy.

RESULTS

Patients were classified as proven IPA (n=11), probable IPA (n=16), possible IPA (n=4), or non-IPA (n=66). The most common underlying disease of patients with IPA was chronic obstructive pulmonary disease (18.5%), and 22.2% patients with IPA had no known diseases. The sensitivities, specificities, and positive and negative predictive values of the GM and BG assays and at least one positive on both assays were 40.7%/89.4%/61.1%/78.7%, 48.1%/78.8%/48.1%/78.8%, and 70.4%/75.8%/54.3%/86.2%, respectively.

CONCLUSION

Compared with the testing of neutropenic patients, the serum GM or BG assay alone was less useful for the diagnosis of IPA in non-neutropenic patients. However, at least one positive result of the two serum assays appeared to be useful in the diagnosis of IPA in non-neutropenic patients.

Invasive pulmonary aspergillosis in patients with chronic obstructive pulmonary disease

Background

Invasive pulmonary aspergillosis (IPA) is an infection often occurring in neutropenic patients and has high mortality rates. In recent years, it has been reported that the incidence of IPA has also increased in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study is to investigate the clinical and demographic characteristics and treatment responses of IPA in patients with COPD.

Methods

Seventy-one patients with a positive culture of Aspergillus from lower respiratory tract samples were examined retrospectively. Eleven (15.4%) of these patients, affected with grade 3 or 4 COPD, had IPA.

Results

Aspergillus hyphae were detected in lung biopsy in three (27.3%) out of 11 patients and defined as proven IPA; a pathological sample was not taken in the other eight (72.7%) patients, and these were defined as probable IPA. Aspergillus isolates were identified as six cases of Aspergillusfumigatus and three of Aspergillusniger in nine patients, while two isolates were not identified at species level. While five patients required intensive care unit admission, four of them received mechanical ventilation. The most common finding on chest X-ray and computed tomography (CT) (respectively 63.6%, 72.7%) was infiltration. Amphotericin B was the initial drug of choice in all patients and five patients were discharged with oral voriconazole after amphotericin B therapy. Six patients (54.5%) died before treatment was completed.

Conclusions

IPA should be taken into account in the differential diagnosis particularly in patients with severe and very severe COPD presenting with dyspnea exacerbation, poor clinical status, and a new pulmonary infiltrate under treatment with broad-spectrum antibiotics and steroids.

β-D-glucan testing is important for diagnosis of invasive fungal infections

Invasive fungal infections are a significant cause of morbidity and mortality in patients who receive immunosuppressive therapy, such as solid organ and hematopoietic stem cell transplant (HSCT) recipients. Many of the fungi associated with these infections are angioinvasive and are best diagnosed by visualizing the organism in or culturing the organism from deep tissue. However, obtaining such tissue often requires an invasive procedure. Many HSCT recipients are thrombocytopenic, making such procedure too risky because of potential bleeding complications. Additionally, positive blood cultures are rare for patients with angioinvasive fungal infections, making this diagnostic strategy of little value. Undiagnosed fungal infections in these patient populations are a significant cause of mortality. Prophylactic use of antifungal agents, such as the echinocandins, during periods of neutropenia or graft-versus-host disease may prevent some fungal infections but increase the risk for others. Detection of fungal antigens in body fluids, including cryptococcus capsular polysaccharide, histoplasma antigen, galactomannan, and β-d-glucan, is viewed as being clinically useful for at least the presumptive diagnosis of invasive fungal infections. β-d-Glucan is an attractive antigen in that it is found in a broad range of fungal agents, including the commonly encountered agents Candida spp., Aspergillus spp., and Pneumocystis jirovecii. Cross-reactions with certain hemodialysis filters, beta-lactam antimicrobials, and immunoglobulins, which raise concerns about false-positive tests, have also been described. As a result, the use of this testing must be closely monitored. In this point-counterpoint, we have asked Elitza Theel, who directs the Infectious Disease Serology Laboratory at the Mayo Clinic, to address why she believes that this test has value in the diagnosis of invasive fungal infections. We have asked Christopher Doern, Director of Clinical Microbiology at Children's Medical Center of Dallas, why he questions the clinical value of β-d-glucan testing.