Galactomannan detection for invasive aspergillosis in immunocompromized patients

The SSS revolution in fungal diagnostics: speed, simplicity and sensitivity

INTRODUCTION

Fungal disease has historically presented a diagnostic challenge due to its often non-specific clinical presentations, relative infrequency and reliance on insensitive and time-intensive fungal culture.

SOURCES OF DATA

We present the recent developments in fungal diagnostics in the fields of serological and molecular diagnosis for the most clinically relevant pathogens; developments that have the potential to revolutionize fungal diagnosis through improvements in speed, simplicity and sensitivity. We have drawn on a body of evidence including recent studies and reviews demonstrating the effectiveness of antigen and antibody detection and polymerase chain reaction (PCR) in patients with and without concurrent human immunodeficiency virus infection.

AREAS OF AGREEMENT

This includes recently developed fungal lateral flow assays, which have a low cost and operator skill requirement that give them great applicability to low-resource settings. Antigen detection for Cryptococcus, Histoplasma and Aspergillus spp. are much more sensitive than culture. PCR for Candida spp., Aspergillus spp., Mucorales and Pneumocystis jirovecii is more sensitive than culture and usually faster.

AREAS OF CONTROVERSY

Effort must be made to utilize recent developments in fungal diagnostics in clinical settings outside of specialist centres and integrate their use into standard medical practice. Given the clinical similarities of the conditions and frequent co-infection, further study is required into the use of serological and molecular fungal tests, particularly in patients being treated for tuberculosis.

GROWING POINTS

Further study is needed to clarify the utility of these tests in low-resource settings confounded by a high prevalence of tuberculosis.

AREAS TIMELY FOR DEVELOPING RESEARCH

The diagnostic utility of these tests may require revision of laboratory work flows, care pathways and clinical and lab coordination, especially for any facility caring for the immunosuppressed, critically ill or those with chronic chest conditions, in whom fungal disease is common and underappreciated.

Utility of Galactomannan Screening for Early Detection of Invasive Aspergillosis in High-Risk Hemato-Oncology Patients

INTRODUCTION

Invasive aspergillosis (IA) affects mainly patients with hematological malignancies, and early diagnosis is crucial for timely treatment. Most diagnoses are based on clinical and mycological criteria, mostly galactomannan (GM) test in serum or bronchoalveolar fluid, which is performed in case of clinical suspicion or as routine screening in patients at high risk who are not receiving anti-mold prophylaxis, for early detection of IA. The aim of this study was to assess in a real-world setting the efficacy of biweekly serum GM screening for the early detection of IA.

METHODS

A retrospective cohort that included 80 adult patients treated at the Hematology Department, Hadassah Medical Center, 2016-2020, with a diagnosis of IA. Clinical and laboratory data were collected from patients' medical files and the rate of GM-driven, GM-associated, and non-GM-associated IA was calculated.

RESULTS

There were 58 patients with IA. The rate of GM-driven diagnosis was 6.9%, GM-associated diagnosis was 43.1%, and non-GM-associated diagnosis was 56.9%. The GM test as a screening tool had led to IA diagnosis in only 0.2% of screened serums with a number needed to screen in order to find 1 patient with IA of 490.

CONCLUSION

Clinical suspicion outweighs GM screening as a tool for early diagnosis of IA. Nevertheless, GM has an important role as a diagnostic tool for IA.

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

The values of (1,3)-β-D-glucan and galactomannan in cases of invasive fungal rhinosinusitis

OBJECTIVE

The purpose of the present study was to investigate the values of the serum (1,3)-β-D-glucan test (G test) alone, the galactomannan test (GM test) alone, and their combination in the diagnosis of invasive fungal rhinosinusitis (IFRS).

METHODS

The present study retrospectively analysed the clinical data of 98 patients who were preliminarily diagnosed with "space-occupying lesions in nose". Of these 98 patients, 88 received the G test, 55 received the GM test, and 45 received both. A pathology analysis was used as the gold standard to diagnose IFRS. All data were analysed using SPSS 19.0.

RESULTS

The sensitivities (Se) of the G and GM tests alone were 60.0% and 28.6%, respectively, whereas the specificities (Sp) were 92.3% and 93.8%, respectively. Moreover, the positive predictive values (PPV) of the G and GM tests alone were 50.0% and 40.0%, respectively, and the negative predictive values (NPV) were 94.7% and 90.0%, respectively. In addition, the diagnostic odds ratios (DOR) were 18.0 and 6.0, respectively, and the Kappa values were 0.48 (P < 0.05) and 0.25 (P > 0.05), respectively. When the G and GM tests were parallel combined, the Se was 66.7%, the Sp was 92.3%, the PPV was 57.1%, the NPV was 94.7%, the DOR was 24.0, and the Kappa value was 0.55 (P < 0.05). The present study was unable to evaluate the serial diagnosis due to the lack of patients testing positive.

CONCLUSIONS

The G/GM tests exhibited low Se and PPV when used to diagnose IFRS, while high Sp and NPV. Parallel diagnosis improved the diagnostic Se and DOR values.

Recent Advances and Novel Approaches in Laboratory-Based Diagnostic Mycology

What was once just culture and microscopy the field of diagnostic mycology has significantly advanced in recent years and continues to incorporate novel assays and strategies to meet the changes in clinical demand. The emergence of widespread resistance to antifungal therapy has led to the development of a range of molecular tests that target mutations associated with phenotypic resistance, to complement classical susceptibility testing and initial applications of next-generation sequencing are being described. Lateral flow assays provide rapid results, with simplicity allowing the test to be performed outside specialist centres, potentially as point-of-care tests. Mycology has responded positively to an ever-diversifying patient population by rapidly identifying risk and developing diagnostic strategies to improve patient management. Nowadays, the diagnostic repertoire of the mycology laboratory employs classical, molecular and serological tests and should be keen to embrace diagnostic advancements that can improve diagnosis in this notoriously difficult field.

Diagnostic value of galactomannan in serum and bronchoalveolar lavage fluid for invasive pulmonary aspergillosis in non-neutropenic patients

OBJECTIVE

To evaluate the diagnostic performance of galactomannan (GM) detection in serum and bronchoalveolar lavage fluid (BALF) for invasive pulmonary aspergillosis (IPA) in non-neutropenic patients.

METHODS

A total of 291 non-neutropenic patients in the Second Xiangya Hospital of Central South University were included. According to the 2019 EORTC/MSG guidelines, all cases were divided into an IPA group (n = 24) and a non-IPA group (n = 267). Receiver operating characteristic (ROC) curves were drawn to compare the diagnostic efficiency of GM detection in BALF and serum.

RESULTS

According to the receiver operating characteristic curves of BALF and serum GM, the areas under the curve were 0.961 and 0.699, respectively. The optimal BALF GM detection was found when the cutoff value was set to 0.87, whereas the sensitivity and specificity were 91.7% and 92.5%, respectively.

CONCLUSIONS

BALF GM detection is more sensitive than serum GM detection for diagnosing IPA, and the optimal cutoff value for BALF GM is 0.87.

An Evaluation of the Performance of the IMMY Aspergillus Galactomannan Enzyme-Linked Immunosorbent Assay When Testing Serum To Aid in the Diagnosis of Invasive Aspergillosis

The objectives of this study were to evaluate the performance of the recently released IMMY Aspergillus galactomannan enzyme immunoassay (IMMY GM-EIA) when testing serum samples and to identify the optimal galactomannan index (GMI) positivity threshold for the diagnosis of invasive aspergillosis (IA). This was a retrospective case/control study, comprising 175 serum samples obtained from 131 patients, 35 of whom had probable or possible invasive fungal disease (IFD) as categorized using recently revised, internationally accepted definitions. The IMMY GM-EIA was performed following the manufacturer's instructions. Performance parameters were determined and receiver operator characteristic analysis was used to identify an optimal GMI threshold. Concordance with the Bio-Rad Aspergillus Ag assay (Bio Rad GM-EIA) and IMMY sona Aspergillus lateral flow assay was assessed. The median GMIs generated by the IMMY GM-EIA for samples originating from probable IA/IFD cases (n = 31), possible IFD (n = 4), and control patients (n = 100) were 0.61, 0.11, and 0.14, respectively, and were comparable to those of the Bio-Rad GM-EIA (0.70, 0.04, and 0.04, respectively). Overall qualitative observed sample agreement between the IMMY GM-EIA and Bio-Rad GM-EIA was 94.7%, generating a kappa statistic of 0.820. At a GMI positivity threshold of ≥0.5, the IMMY GM-EIA had a sensitivity and specificity of 71% and 98%, respectively. Reducing the threshold to ≥0.27 generated sensitivity and specificity of 90% and 92%, respectively. The IMMY GM-EIA provides a comparable alternative to the Bio-Rad GM-EIA when testing serum samples. Further prospective, multicenter evaluations are required to confirm the optimal threshold and associated clinical performance.

Fatal Invasive Pulmonary Aspergillosis in COVID-19 Patient with Acute Myeloid Leukemia in Iran

Although patients with severe immunodeficiency and hematological malignancies has been considered at highest risk for invasive fungal infection, patients with severe pneumonia due to influenza, and severe acute respiratory syndrome coronavirus (SARS-CoV) are also at a higher risk of developing invasive pulmonary aspergillosis (IPA). Recently, reports of IPA have also emerged among SARS-CoV-2 infected patients admitted to intensive care units (ICUs). Here, we report a fatal case of probable IPA in an acute myeloid leukemia patient co-infected with SARS-CoV-2 and complicated by acute respiratory distress syndrome (ARDS). Probable IPA is supported by multiple pulmonary nodules with ground glass opacities which indicate halo sign and positive serum galactomannan results. Screening studies are needed to evaluate the prevalence of IPA in immunocompromised patients infected with SARS-CoV-2. Consequently, testing for the presence of Aspergillus in lower respiratory secretions and galactomannan in consecutive serum samples of COVID-19 patients with timely and targeted antifungal therapy based on early clinical suspicion of IPA are highly recommended.

Evaluation of the Performance of the IMMY sona Aspergillus Galactomannan Lateral Flow Assay When Testing Serum To Aid in Diagnosis of Invasive Aspergillosis

Management of invasive aspergillosis has been improved by biomarker assays, but limited accessibility and batch testing limit the impact. Lateral flow assays (LFA) are a simple method for use outside specialist centers, provided performance is acceptable. The objective of this study was to determine the performance of the recently released IMMY sona Aspergillus LFA when testing serum samples. The study took the form of a retrospective, anonymous case/control study comprising 179 serum samples from 136 patients with invasive fungal disease, previously documented using recently revised internationally accepted definitions. The LFA was performed following the manufacturer's instructions using a cube reader to generate a galactomannan index (GMI). Performance parameters were determined, and receiver operator characteristic (ROC) analysis was used to identify an optimal threshold. Concordance with the Bio-Rad Aspergillus Ag assay (GM-EIA) was performed. At the recommended positivity threshold (GMI ≥ 0.5), LFA sensitivity and specificity were 96.9% (31/32) and 98% (98/100), respectively. ROC analysis confirmed the optimal threshold and generated an area under the curve of 0.9919. Qualitative agreement between LFA and GM-EIA was 89.0%, generating a Kappa statistic of 0.698, representing good agreement, with most discordance arising due to false-negative GM-EIA samples that were positive by LFA. The median GMI generated by the LFA was significantly greater than that generated by the GM-EIA. The IMMY sona Aspergillus LFA, when used with a cube reader, provides a rapid alternative to the well-established GM-EIA, potentially detecting more GM epitopes and enhancing sensitivity.

Frequency of Invasive Fungal Disease in Adults: Experience of a Specialized Laboratory in Medellín, Colombia (2009-2015)

Invasive fungal diseases (IFD) contribute significantly to worldwide morbidity and mortality, but their frequency is not well-described in some countries. The present work describes the frequency of IFD in a specialized laboratory in Colombia. A retrospective, descriptive study was implemented between March 2009 and December 2015. Results: 13,071 patients with clinical suspicion of IFD were referred during the study period, from which 33,516 biological samples were processed and analyzed using 14 laboratory methods. Diagnosis was confirmed in 1425 patients (11%), distributed according to the mycoses of interest analyzed here: histoplasmosis in 641/11,756 patients (6%), aspergillosis in 331/10,985 patients (3%), cryptococcosis in 239/8172 patients (3%), pneumocystosis in 111/1651 patients (7%), paracoccidioidomycosis in 60/10,178 patients (0.6%), and invasive candidiasis in 48/7525 patients (0.6%). From the first year of the study period to the last year, there was a 53% increase in the number of cases of IFD diagnosed. Our laboratory experienced a high frequency of IFD diagnosis, possibly attributable to the availability of a greater range of diagnostic tools. Frequency of IFD in this study was atypical compared with other studies, probably as a result of the single laboratory-site analysis. This demonstrates that implementing educational strategies helps to create a high index of clinical suspicion, while the availability and utilization of appropriate diagnostic assays assure greater reliability in identification of these cases.

Polymerase chain reaction blood tests for the diagnosis of invasive aspergillosis in immunocompromised people

BACKGROUND

This is an update of the original review published in the Cochrane Database of Systematic Reviews Issue 10, 2015.Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mould infection in immunocompromised people. Early diagnosis of IA and prompt administration of appropriate antifungal treatment are critical to the survival of people with IA. Antifungal drugs can be given as prophylaxis or empirical therapy, instigated on the basis of a diagnostic strategy (the pre-emptive approach) or for treating established disease. Consequently, there is an urgent need for research into both new diagnostic tools and drug treatment strategies. Increasingly, newer methods such as polymerase chain reaction (PCR) to detect fungal nucleic acids are being investigated.

OBJECTIVES

To provide an overall summary of the diagnostic accuracy of PCR-based tests on blood specimens for the diagnosis of IA in immunocompromised people.

SEARCH METHODS

We searched MEDLINE (1946 to June 2015) and Embase (1980 to June 2015). We also searched LILACS, DARE, Health Technology Assessment, Web of Science and Scopus to June 2015. We checked the reference lists of all the studies identified by the above methods and contacted relevant authors and researchers in the field. For this review update we updated electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 3) in the Cochrane Library; MEDLINE via Ovid (June 2015 to March week 2 2018); and Embase via Ovid (June 2015 to 2018 week 12).

SELECTION CRITERIA

We included studies that: i) compared the results of blood PCR tests with the reference standard published by the European Organisation for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG); ii) reported data on false-positive, true-positive, false-negative and true-negative results of the diagnostic tests under investigation separately; and iii) evaluated the test(s) prospectively in cohorts of people from a relevant clinical population, defined as a group of individuals at high risk for invasive aspergillosis. Case-control and retrospective studies were excluded from the analysis.

DATA COLLECTION AND ANALYSIS

Authors independently assessed quality and extracted data. For PCR assays, we evaluated the requirement for either one or two consecutive samples to be positive for diagnostic accuracy. We investigated heterogeneity by subgroup analyses. We plotted estimates of sensitivity and specificity from each study in receiver operating characteristics (ROC) space and constructed forest plots for visual examination of variation in test accuracy. We performed meta-analyses using the bivariate model to produce summary estimates of sensitivity and specificity.

MAIN RESULTS

We included 29 primary studies (18 from the original review and 11 from this update), corresponding to 34 data sets, published between 2000 and 2018 in the meta-analyses, with a mean prevalence of proven or probable IA of 16.3 (median prevalence 11.1% , range 2.5% to 57.1%). Most patients had received chemotherapy for haematological malignancy or had undergone hematopoietic stem cell transplantation. Several PCR techniques were used among the included studies. The sensitivity and specificity of PCR for the diagnosis of IA varied according to the interpretative criteria used to define a test as positive. The summary estimates of sensitivity and specificity were 79.2% (95% confidence interval (CI) 71.0 to 85.5) and 79.6% (95% CI 69.9 to 86.6) for a single positive test result, and 59.6% (95% CI 40.7 to 76.0) and 95.1% (95% CI 87.0 to 98.2) for two consecutive positive test results.

AUTHORS' CONCLUSIONS

PCR shows moderate diagnostic accuracy when used as screening tests for IA in high-risk patient groups. Importantly the sensitivity of the test confers a high negative predictive value (NPV) such that a negative test allows the diagnosis to be excluded. Consecutive positives show good specificity in diagnosis of IA and could be used to trigger radiological and other investigations or for pre-emptive therapy in the absence of specific radiological signs when the clinical suspicion of infection is high. When a single PCR positive test is used as the diagnostic criterion for IA in a population of 100 people with a disease prevalence of 16.3% (overall mean prevalence), three people with IA would be missed (sensitivity 79.2%, 20.8% false negatives), and 17 people would be unnecessarily treated or referred for further tests (specificity of 79.6%, 21.4% false positives). If we use the two positive test requirement in a population with the same disease prevalence, it would mean that nine IA people would be missed (sensitivity 59.6%, 40.4% false negatives) and four people would be unnecessarily treated or referred for further tests (specificity of 95.1%, 4.9% false positives). Like galactomannan, PCR has good NPV for excluding disease, but the low prevalence of disease limits the ability to rule in a diagnosis. As these biomarkers detect different markers of disease, combining them is likely to prove more useful.

Characterization of the putative polysaccharide synthase CpsA and its effects on the virulence of the human pathogen Aspergillus fumigatus

The fungus Aspergillus fumigatus is a ubiquitous opportunistic human pathogen capable of causing a life-threatening disease called invasive aspergillosis, or IA, with an associated 40-90% mortality rate in immunocompromised patients. Of the approximately 250 species known in the genus Aspergillus, A. fumigatus is responsible for up to 90% of IA infections. This study focuses on examining the role of the putative polysaccharide synthase cpsA gene in A. fumigatus virulence. Additionally, we evaluated its role in cellular processes that influence invasion and colonization of host tissue. Importantly, our results support that cpsA is indispensable for virulence in A. fumigatus infection of non-neutropenic hosts. Our study revealed that cpsA affects growth and sporulation in this fungus. Absence of cpsA resulted in a drastic reduction in conidiation, and forced overexpression of cpsA produced partially fluffy colonies with low sporulation levels, suggesting that wild-type cpsA expression levels are required for proper conidiation in this fungus. This study also showed that cpsA is necessary for normal cell wall integrity and composition. Furthermore, both deletion and overexpression of cpsA resulted in a reduction in the ability of A. fumigatus to adhere to surfaces, and caused increased sensitivity to oxidative stress. Interestingly, metabolomics analysis indicated that cpsA affects A. fumigatus secondary metabolism. Forced overexpression of cpsA resulted in a statistically significant difference in the production of fumigaclavine A, fumigaclavine B, fumigaclavine C, verruculogen TR-2, and tryprostatin A.

Diagnosing Invasive Pulmonary Aspergillosis in Hematology Patients: a Retrospective Multicenter Evaluation of a Novel Lateral Flow Device

Invasive pulmonary aspergillosis (IPA) is a potentially lethal infection in patients with hematological diseases or following allogeneic stem cell transplantation. Early diagnosis is essential, as delayed treatment results in increased mortality. Recently, a lateral flow device (LFD) for the diagnosis of IPA was CE marked and made commercially available by OLM Diagnostics. We retrospectively analyzed bronchoalveolar lavage fluid (BALf) collected from adult hematology patients from 4 centers in The Netherlands and Belgium. Galactomannan was retested in all samples. All samples were applied to an LFD and read out visually by two independent researchers blinded to the diagnosis of the patient. All samples were also read out using a digital reader. We included 11 patients with proven IPA, 68 patients with probable IPA, 44 patients with possible IPA, and 124 patients with no signs of IPA (controls). In cases of proven IPA versus controls, sensitivity and specificity were 0.82 and 0.86 for visual readout and 0.82 and 0.96 for digital readout, respectively. When comparing patients with proven and probable IPA as cases versus controls, sensitivity and specificity were found to be 0.71 and 0.86, respectively. When excluding serum and BALf galactomannan as mycological criteria from the 2008 European Organization for Research and Treatment of Cancer Invasive Fungal Infections Cooperative Group (EORTC)/Mycoses Study Group of the National Institute of Allergy and Infectious Diseases (MSG) consensus definitions, the LFD was less specific than galactomannan when comparing subjects with proven and probable IPA to controls (0.86 versus 0.96; P = 0.005) but had similar sensitivity (0.76 versus 0.85; P = 0.18). In conclusions, in this large study of the CE-marked LFD in BALf from hematology patients, the LFD had a good performance for the diagnosis of IPA.

Breakthrough invasive aspergillosis and diagnostic accuracy of serum galactomannan enzyme immune assay during acute myeloid leukemia induction chemotherapy with posaconazole prophylaxis

Posaconazole prophylaxis has demonstrated efficacy in the prevention of invasive aspergillosis during prolonged neutropenia following acute myeloid leukemia induction chemotherapy. Antifungal treatment decreases serum galactomannan enzyme immunoassay diagnostic accuracy that could delay the diagnosis and treatment.

We retrospectively studied patients with acute myeloid leukemia who underwent intensive chemotherapy and antifungal prophylaxis by posaconazole oral suspension. Clinical, radiological, microbiological features and treatment response of patients with invasive aspergillosis that occurred despite posaconazole prophylaxis were analyzed. Diagnostic accuracy of serum galactomannan assay according to posaconazole plasma concentrations has been performed.

A total of 288 patients with acute myeloid leukemia, treated by induction chemotherapy, who received posaconazole prophylaxis for more than five days were included in the present study. The incidence of invasive aspergillosis was 8% with 12 (4.2%), 8 (2.8%) and 3 (1%), possible, probable and proven invasive aspergillosis, respectively. Posaconazole plasma concentration was available for 258 patients. Median duration of posaconazole treatment was 17 days, and median posaconazole plasma concentration was 0.5 mg/L. None of patients with invasive aspergillosis and posaconazole concentration ≥ 0.5 mg/L had a serum galactomannan positive test. Sensitivity of serum galactomannan assay to detect probable and proven invasive aspergillosis was 81.8%. Decreasing the cut-off value for serum galactomannan optical density index from 0.5 to 0.3 increased sensitivity to 90.9%.

In a homogenous cohort of acute myeloid leukemia patients during induction chemotherapy, increasing the posaconazole concentration decreases the sensitivity of serum galactomannan assay.

Use of Galactomannan Antigen and Aspergillus DNA Real-time Polymerase Chain Reaction as Routine Methods for Invasive Aspergillosis in Immunosuppressed Children in Greece

PURPOSE

Invasive aspergillosis (IA) remains a critical issue in immunosuppressed patients. Detection of galactomannan antigen (GM) in serum samples is included as a criterion of IA by the European Organization for the Research and Treatment of Cancer/Mycoses Study Group. Nevertheless, Aspergillus DNA detection by polymerase chain reaction (PCR) has not yet been included because clinical data validation is lacking. The present study describes the simultaneous performance of GM and PCR tests as routine methods for IA diagnosis.

METHODS

During the period January 2012 to December 2017, a total of 156 white children hospitalized in a tertiary children's hospital of Athens (97 boys and 59 girls; age range, 5 months-14 years) were examined as possible cases of IA. Patients were classified into 4 groups based on their underlying diseases: hematologic malignancies (107 of 156 [68.6%]), solid tumors (16 of 156 [10.2%]), primary immunodeficiency (12 of 156 [7.7%]), and hereditary immunodeficiency (21 of 156 [13.5%]). GM detection was made with the Platelia Aspergillus Ag kit (Bio-Rad Laboratories, Hercules, California). Sera with a cut-off index ≥0.5 on at least 2 separate blood collections were considered positive. Serum detection of Aspergillus DNA was conducted with real-time PCR MycAssay Aspergillus assay (Myconostica Ltd, Cambridge, United Kingdom). PCR positivity was determined by using a threshold of 38 cycles in at least 1 serum sample. Four or more successive samples per patient were tested.

FINDINGS

Overall, 28 of 156 patients (53 of 744 serum samples) were found positive. Eleven patients were positive using both methods (24 samples). Four children were positive only by PCR (6 samples), whereas 13 (23 samples) were positive only with GM in consecutive samples. Agreement of both methods, GM(+)/PCR(+) or GM(-)/PCR(-), was found in 139 patients (90% of total patients) and 715 samples (96.1% of total samples). The agreement of both methods was found: (1) 85% in patients with hematologic malignancies; (2) 100% in patients with solid tumors; (3) 97.5% in patients with primary immunodeficiency; and (4) 98.8% in patients with hereditary immunodeficiency. Overall disagreement was observed in 17 patients, in which the positive result in any of the 2 methods was estimated as true positive in conjunction with radiologic and other clinical findings.

IMPLICATIONS

The combination of GM and PCR, provided high diagnostic accuracy in consecutive samples (twice a week). Clinical, radiologic, and other laboratory findings should be taken into consideration in the evaluation of GM and PCR.

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.

Circulating Aspergillus fumigatus DNA Is Quantitatively Correlated to Galactomannan in Serum

The performance of antigen galactomannan (GM) for diagnosing invasive aspergillosis (IA) is hampered by the occurrence of false-positive results. Quantitative PCR has been proposed to improve the diagnosis of IA. Therefore, we analyzed the value of performing a PCR test to the GM-positive serum sample. Using a quantitative PCR assay specific for Aspergillus fumigatus 28S ribosomal DNA, we retrospectively tested 422 GM-positive (Platelia Bio-Rad kit) serum samples collected over 1 year from 147 patients. The cases were classified based on EORTC criteria as “proven,” “probable,” and “no–IA” before availability of the PCR results. After exclusion of 65 samples for non-reproducibility of GM positivity (n = 62) or PCR inhibition (n = 3), 75 (21.0%) of the remaining 357 samples were PCR-positive. GM and fungal DNA showed a significantly positive correlation (p < 0.0001, R² = 0.27, slope = 0.98 ± 0.19). At least one PCR-positive result was observed in 63.3% (31/49) of IA patients and in 13.2% (13/98) of non-IA patients (p < 0.0001). The PCR positivity was also associated with the presence of other microbiological criteria among the 44 patients with IA and complete mycological workup (p = 0.014), as well as a higher mortality rate at six months among the 135 patients with hematological conditions (p = 0.0198). Overall, we found a quantitative correlation between serum GM and circulating DNA with an increased likelihood of IA when both were positive. A PCR-positive result also supported a higher fungal load when GM was already positive. We advocate adding a PCR test for every confirmed GM-positive serum sample.

Diagnosing filamentous fungal infections in immunocompromised patients applying computed tomography-guided percutaneous lung biopsies: a 12-year experience

Background

Invasive fungal diseases (IFD) are an important cause of morbidity and mortality in immunocompromised patients, and early diagnosis and management are a challenge. We evaluated the clinical utility of computed tomography (CT)-guided percutaneous lung biopsies in diagnosing IFD.

Methods

Between 2003 and 2014, we analyzed 2671 CT-guided lung biopsies, from which 157 were IFD associated; we aimed to determine microbiological-based diagnostic accuracy of calcofluor white staining (CFWS), culture, Aspergillus antigen detection (GM), broad-range fungal PCR, and Aspergillus PCR per sample.

Results

127 (81%) specimens were microscopically positive for any fungal elements, 30 (19%) negative. Aspergillus and non-Aspergillus like hyphae were obtained in 85 (67%) and 42 (33%) specimens, respectively. CFWS positivity was defined as proof of infection. Sensitivity, specificity, and positive (PPV) and negative predictive (NPV) values for CT scan were 100, 44, 80, and 100%, for Aspergillus PCR 89, 58, 88, and 58%, for broad-range fungal PCR 90, 83, 95, and 90%, and for GM 94, 83, 95, and 90%. The most common CT features were patchy opacifications with central necrosis (78%) or cavern defects (50%), less common were air bronchograms (39%) or ground glass halos (39%), and all other features were rare. The overall pneumothorax rate subsequent to biopsy was 19%, but in only 2% of all cases the placement of a chest tube was indicated. One case of fatal air embolism occurred.

Conclusions

CT-guided lung biopsies have high diagnostic accuracy in terms of microscopic examination, and complication rates are low. Molecular-based and antigen tests applied on fungal hyphae-positive specimens showed comparable results.

Antifungal stewardship considerations for adults and pediatrics

Antifungal stewardship refers to coordinated interventions to monitor and direct the appropriate use of antifungal agents in order to achieve the best clinical outcomes and minimize selective pressure and adverse events. Antifungal utilization has steadily risen over time in concert with the increase in number of immunocompromised adults and children at risk for invasive fungal infections (IFI). Challenges in diagnosing IFI often lead to delays in treatment and poorer outcomes. There are also emerging data linking prior antifungal exposure and suboptimal dosing to the emergence of antifungal resistance, particularly for Candida. Antimicrobial stewardship programs can take a multi-pronged bundle approach to ensure suitable prescribing of antifungals via post-prescription review and feedback and/or prior authorization. Institutional guidelines can also be developed to guide diagnostic testing in at-risk populations; appropriate choice, dose, and duration of antifungal agent; therapeutic drug monitoring; and opportunities for de-escalation and intravenous-to-oral conversion.

Measuring the statistical validity of summary meta-analysis and meta-regression results for use in clinical practice

An important question for clinicians appraising a meta‐analysis is: are the findings likely to be valid in their own practice—does the reported effect accurately represent the effect that would occur in their own clinical population? To this end we advance the concept of statistical validity—where the parameter being estimated equals the corresponding parameter for a new independent study. Using a simple (‘leave‐one‐out’) cross‐validation technique, we demonstrate how we may test meta‐analysis estimates for statistical validity using a new validation statistic, Vn, and derive its distribution.

We compare this with the usual approach of investigating heterogeneity in meta‐analyses and demonstrate the link between statistical validity and homogeneity. Using a simulation study, the properties of Vn and the Q statistic are compared for univariate random effects meta‐analysis and a tailored meta‐regression model, where information from the setting (included as model covariates) is used to calibrate the summary estimate to the setting of application. Their properties are found to be similar when there are 50 studies or more, but for fewer studies Vn has greater power but a higher type 1 error rate than Q. The power and type 1 error rate of Vn are also shown to depend on the within‐study variance, between‐study variance, study sample size, and the number of studies in the meta‐analysis. Finally, we apply Vn to two published meta‐analyses and conclude that it usefully augments standard methods when deciding upon the likely validity of summary meta‐analysis estimates in clinical practice. © 2017 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.

Laboratory Diagnostics for Fungal Infections: A Review of Current and Future Diagnostic Assays

This article reviews the current diagnostic approaches, both serologic and molecular, for the detection of fungi associated with pulmonary disease. Classic serologic techniques, including immunodiffusion and complement fixation, both of which remain a cornerstone for fungal diagnostic testing, are reviewed and their performance characteristics presented. More recent advances in this field, including novel lateral-flow assays for fungal antigen detection, are also described. Molecular techniques for fungal identification both from culture and directly from patient specimens, including nucleic acid probes, mass spectrometry-based methods, nucleic acid amplification testing, and traditional and broad-range sequencing, are discussed and their performance evaluated.

Successful treatment of azole-resistant invasive aspergillosis in a bottlenose dolphin with high-dose posaconazole

Invasive aspergillosis due to azole-resistant Aspergillus fumigatus is difficult to manage. We describe a case of azole-resistant invasive aspergillosis in a female bottlenose dolphin, who failed to respond to voriconazole and posaconazole therapy. As intravenous therapy was precluded, high dose posaconazole was initiated aimed at achieving trough levels exceeding 3 mg/l. Posaconazole serum levels of 3–9.5 mg/l were achieved without significant side-effects. Follow-up bronchoscopy and computed tomography showed complete resolution of the lesions.

Challenges in microbiological diagnosis of invasive Aspergillus infections

Invasive aspergillosis (IA) has been increasingly reported in populations other than the historical hematology patients and there are new questions about the performance of microbiological tools. Microscopy and culture have been completed by biomarkers, either antigens or DNA, and in blood or respiratory specimens or both. First studied in hematology, the antigen galactomannan performance in serum is low in other patient populations where the pathophysiology of the infection can be different and the prevalence of IA is much lower. DNA detection with polymerase chain reaction (PCR) in blood or serum (or both) has reached a certain level of acceptance thanks to consensus methods based on real-time quantitative PCR (qPCR). When used on respiratory specimens, galactomannan and qPCR depend on standardization of the sampling and the diverse mycological procedures. Thus, culture remains the main diagnostic criterion in critically ill patients. The current trend toward more effective anti-mold prophylaxis in hematology hampers the yield of a screening strategy, as is usually performed in hematology. Therefore, circulating biomarkers as confirmatory tests should be considered and their performance should be reappraised in each new setting. The use of azole prophylaxis also raises the issue of selecting azole-resistance Aspergillus fumigatus isolates. Ideally, the biomarkers will be more efficient when individual genetic risks of IA are defined. Culture, though not standardized, remains a key element for the diagnosis of IA and has the advantage to easily detect molds other than A. fumigatus. It is still unclear whether next-generation sequencing will replace culture in the future.

Defining the clinical pathway in cochrane diagnostic test accuracy reviews

BACKGROUND

The value of a medical test depends on the context in which it might be used. Ideally, questions, results and conclusions of a diagnostic test accuracy (DTA) systematic review should be presented in light of this context. There is increasing acceptance of the value for knowing the impact a test can have on downstream consequences such as costs, implications for further testing and treatment options however there is currently no explicit guidance on how to address this. Authors of a Cochrane diagnostic review have recently been asked to include the clinical pathway in which a test maybe used. We aimed to evaluate how authors were developing their clinical pathways in the light of this.

METHODS

We searched the Cochrane Database of Systematic Reviews for all published DTA reviews. We included only those reviews that included a clinical pathway. We developed a checklist, based on the guidance in the Cochrane Handbook for DTA review authors. To this, we added a number of additional descriptors. We checked if the included pathways fulfilled these descriptors as defined by our checklist.

RESULTS

We found 47 reviews, of which 33 (73 %) contained aspects pertaining to a clinical pathway. The 33 reviews addressed the clinical pathway differently, both in content and format. Of these, 21 provided a textual description and 12 include visual and textual descriptions. There was considerable variation in how comprehensively review authors adhered to our checklist. Eighteen reviews (51 %) linked the index test results to downstream clinical management actions and patient consequences, but only eight went on to differentially report on the consequences for false negative results and nine on the consequences for false positive results.

CONCLUSION

There is substantial variation in the clinical pathway descriptions in Cochrane systematic reviews of test accuracy. Most reviews do not link misclassifications (i.e. false negatives and false positive) to downstream patient consequences. Review authors could benefit from more explicit guidance on how to create such pathways, which in turn can help guide them in their evidence selection and appraisal of the evidence in the context of downstream consequences of testing.

Comparison of 1,3-β-d-glucan with galactomannan in serum and bronchoalveolar fluid for the detection of Aspergillus species in immunosuppressed mechanical ventilated critically ill patients

PURPOSE

Invasive pulmonary aspergillosis (IPA) is an important cause of morbidity/mortality in immunocompromised critically ill patients. New diagnostic strategies for early detection of IPA include the noninvasive biomarkers 1,3-β-d-glucan (BDG), serum, and bronchoalveolar (BAL) fluid galactomannan (GM). The aim of this study was to compare these markers for early detection of IPA in immunosuppressed critically ill patients.

METHODS

Between December 2014 and December 2015, 49 immunosuppressed patients with respiratory failure were treated at our intensive care unit (ICU). We compared the BDG Fungitell assay with GM Platelia assay in serum and BAL for early detection of IPA. All tests were performed initially after admission at the ICU.

RESULTS

In our study with 49 patients, 13 (26%) had probable IPA. These patients had a higher Acute Physiology And Chronic Health Evaluation II score (28 vs 23, P<.001), Sequential Organ Failure Assessment score (16 vs 14, P<.001), more neutropenia (77% vs 30%, P<.001), worse Horowitz Index (99 vs 73 P<.020), a longer ICU stay (26 vs 17 days, P<.044), and a higher mortality rate (77% vs 58%, P<.001) as compared with patients without probable IPA. The used biomarker BDG presented in patients with probable IPA showed significantly higher levels as compared with patients without probable IPA (375 [103-1000 pg/mL; P<.001] vs 64 [30-105 pg/mL; P < .001]). Comparison of BDG with GM showed that positive serum GM could be detected in only 4 (30%), whereas positive BAL GM could be detected in 12 (92%; mean optical density index, 3.7) of 13 probable IPA cases. These results can be expressed as an overall sensitivity of 88% and a specificity of 82% for probable IPA using the BDG Fungitell assay, a sensitivity of 35% and a specificity of 70% using the serum GM Platelia assay, and a sensitivity of 70% and a specificity of 94% using the BAL GM Platelia assay. The negative predictive values of the used tests were 94% for the BDG Fungitell assay, 94% for the serum GM Platelia assay, and 90% for the BAL GM Platelia assay.

CONCLUSION

1,3-β-d-Glucan may be a useful marker for patients under surveillance at risk for IPA. In critically ill patients with immunosuppression, early diagnosis of IPA may be improved by BDG as compared with serum GM. However, diagnostic performance and accuracy increase when BDG is run in parallel with GM from BAL; moreover, the association of the 2 parameters has also the advantage of detecting early and reliable IPA.

Galactomannan and 1,3-β-d-Glucan Testing for the Diagnosis of Invasive Aspergillosis

Invasive aspergillosis (IA) is a severe complication among hematopoietic stem cell transplant recipients or patients with hematological malignancies and neutropenia following anti-cancer therapy. Moreover, IA is increasingly observed in other populations, such as solid-organ transplant recipients, patients with solid tumors or auto-immune diseases, and among intensive care unit patients. Frequent delay in diagnosis is associated with high mortality rates. Cultures from clinical specimens remain sterile in many cases and the diagnosis of IA often only relies on non-specific radiological signs in the presence of host risk factors. Tests for detection of galactomannan- (GM) and 1,3-β-d-glucan (BDG) are useful adjunctive tools for the early diagnosis of IA and may have a role in monitoring response to therapy. However, the sensitivity and specificity of these fungal biomarkers are not optimal and variations between patient populations are observed. This review discusses the role and interpretation of GM and BDG testing for the diagnosis of IA in different clinical samples (serum, bronchoalveolar lavage fluid, cerebrospinal fluid) and different groups of patients (onco-hematological patients, solid-organ transplant recipients, other patients at risk of IA).

Pediatric Invasive Aspergillosis

Invasive aspergillosis (IA) is a disease of increasing importance in pediatrics due to growth of the immunocompromised populations at risk and improvements in long-term survival for many of these groups. While general principles of diagnosis and therapy apply similarly across the age spectrum, there are unique considerations for clinicians who care for children and adolescents with IA. This review will highlight important differences in the epidemiology, clinical manifestations, diagnosis, and therapy of pediatric IA.

Detection of Aspergillus fumigatus in Blood Samples from Critically Ill Patients in Intensive Care Units by Use of the SeptiFast Assay

We retrospectively analyzed the performance and relevance of the SeptiFast assay in detecting Aspergillus fumigatus DNA in whole blood samples from 38 critically ill intensive care unit (ICU) patients with probable or proven invasive aspergillosis (IA) and 100 ICU patients without IA. The assay exhibited 66% sensitivity, 98% specificity, a 93% positive predictive value, and an 88% negative predictive value. A. fumigatus DNAemia was associated with poor outcome.

Comparison of Serum Galactomannan and 1,3-Beta-D-Glucan Determination for Early Detection of Invasive Pulmonary Aspergillosis in Critically Ill Patients with Hematological Malignancies and Septic Shock

INTRODUCTION

Invasive pulmonary aspergillosis (IPA) is an important cause of morbidity/mortality in critically ill patients with hematological malignancies. New diagnosis strategies include the noninvasive biomarkers 1,3-beta-D-glucan (BDG) and serum galactomannan (GM).

METHODS

For early detection of IPA, we compared BDG Fungitell assay with GM Platelia assay.

RESULTS

Twenty-two out of 30 patients (74 %) had elevated BDG levels (mean 306 pg/ml) beyond the cutoff of 80 pg/ml. GM levels were elevated in only 3 patients (10 %) over the ODI cutoff of >0.5. Following the BDG/GM and microbiological findings, 10 (34 %) cases were classified as probable IPA and 12 (40 %) as possible IPA. Eight (26 %) were classified as no IPA. An overall sensitivity of 90 % (95 % CI 86-96 %) and specificity of 85 % (95 % CI 79-86 %) was found for the BDG Fungitell assay in IPA. In contrast, an overall sensitivity of 30 % (95 % CI 26-38 %) and specificity of 98 % (95 % CI 94-100 %) was found for the GM Platelia assay. A false-negative rate of 70 % for probable IPA and 85 % for probable/possible IPA was detected for GM. The false-negative rate for BDG was 0 % in cases of probable IPA and 45 % in cases of possible cases.

CONCLUSION

BDG is a sensitive marker for patients' surveillance at risk of IPA. In patients with hematological malignancies and septic shock, early diagnosis of IPA might be significantly improved by BDG compared to GM, also considering that BDG has the advantage of detecting fungal diseases other than IPA.

Aspergillus Biofilm In Vitro and In Vivo

In vivo, Aspergillus fumigatus grows as a typical biofilm with hyphae covered by an extracellular matrix (ECM) composed of polysaccharides, galactomannan, and galactosaminogalactan. α1,3 glucans and melanin are also constitutive of the ECM in aspergilloma but not in invasive aspergillosis. In vitro, two biofilm models were established to mimic the in vivo situation. The first model (model 1) uses submerged liquid conditions and is characterized by slow growth, while the second model (model 2) uses agar medium and aerial conditions and is characterized by rapid growth. The composition of the ECM was studied only in the second model and has been shown to be composed of galactomannan, galactosaminogalactan (GAG), and α1,3 glucans, melanin, antigens, and hydrophobins. The presence of extracellular DNA was detected in model 1 biofilm but not in model 2. Transcriptomic analysis employing both biofilm models showed upregulation of genes coding for proteins involved in the biosynthesis of secondary metabolites, adhesion, and drug resistance. However, most data on A. fumigatus biofilms have been obtained in vitro and should be confirmed using in vivo animal models. There is a need for new therapeutic antibiofilm strategies that focus on the use of combination therapy, since biofilm formation poses an important clinical problem due to their resistance to antifungal agents. Furthermore, in vivo investigations of A. fumigatus biofilms that incorporate the associated microbiota are needed. Such studies will add another layer of complexity to our understanding of the role of A. fumigatus biofilm during lung invasion.

Galactomannan in bronchoalveolar lavage fluid for diagnosis of invasive aspergillosis in non-hematological patients

BACKGROUND

The role of galactomannan (GM) in serum or bronchoalveolar lavage fluid (BALF) for the diagnosis of invasive pulmonary aspergillosis (IPA) has been extensively evaluated in hematological patients, however its performance in non-hematological patients is not well established.

METHODS

We performed a multicenter retrospective study in 3 university hospitals in Madrid, Spain between 2010 and 2014. The study population comprised patients with chronic obstructive pulmonary disease (COPD) and patients with immunosuppressive conditions in whom IPA was suspected and for whom BALF GM was available. Patients with hematological disorders were excluded.

RESULTS

A total of 188 patients (35 with COPD and 153 with immunosuppressive conditions) were analyzed, and 31 cases of IPA (proven or probable) were identified. The global sensitivity of BALF GM (optical density index [ODI] ≥ 1.0) was 77.4%; sensitivity was higher in patients with immunosuppressive conditions than in patients with COPD (81.8% vs 66.7%; p: 0.38). In COPD patients, the best performance was obtained for BALF GM (ODI ≥ 0.5), although sensitivity (88.9%) was similar to that of BALF fungal culture (88.9%). The sensitivity of GM in serum was very poor in both populations (36.4% and 11.6%, respectively).

CONCLUSIONS

In the present series, the diagnostic performance of BALF GM was good for IPA in non-hematological patients, especially in patients with immunosuppressive conditions.

Detection of Airway Colonization by Aspergillus fumigatus by Use of Electronic Nose Technology in Patients with Cystic Fibrosis

Currently, there is no noninvasive test that can reliably diagnose early invasive pulmonary aspergillosis (IA). An electronic nose (eNose) can discriminate various lung diseases through an analysis of exhaled volatile organic compounds. We recently published a proof-of-principle study showing that patients with prolonged chemotherapy-induced neutropenia and IA have a distinct exhaled breath profile (or breathprint) that can be discriminated with an eNose. An eNose is cheap and noninvasive, and it yields results within minutes. We determined whether Aspergillus fumigatus colonization may also be detected with an eNose in cystic fibrosis (CF) patients. Exhaled breath samples of 27 CF patients were analyzed with a Cyranose 320. Culture of sputum samples defined the A. fumigatus colonization status. eNose data were classified using canonical discriminant analysis after principal component reduction. Our primary outcome was cross-validated accuracy, defined as the percentage of correctly classified subjects using the leave-one-out method. The P value was calculated by the generation of 100,000 random alternative classifications. Nine of the 27 subjects were colonized by A. fumigatus. In total, 3 subjects were misclassified, resulting in a cross-validated accuracy of the Cyranose detecting IA of 89% (P = 0.004; sensitivity, 78%; specificity, 94%). Receiver operating characteristic (ROC) curve analysis showed an area under the curve (AUC) of 0.89. The results indicate that A. fumigatus colonization leads to a distinctive breathprint in CF patients. The present proof-of-concept data merit external validation and monitoring studies.

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.

Polymerase chain reaction blood tests for the diagnosis of invasive aspergillosis in immunocompromised people

BACKGROUND

Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mould infection in immunocompromised people. Early diagnosis of IA and prompt administration of appropriate antifungal treatment are critical to the survival of people with IA. Antifungal drugs can be given as prophylaxis or empirical therapy, instigated on the basis of a diagnostic strategy (the pre-emptive approach) or for treating established disease. Consequently there is an urgent need for research into both new diagnostic tools and drug treatment strategies. Newer methods such as polymerase chain reaction (PCR) to detect fungal nucleic acids are increasingly being investigated.

OBJECTIVES

To provide an overall summary of the diagnostic accuracy of PCR-based tests on blood specimens for the diagnosis of IA in immunocompromised people.

SEARCH METHODS

We searched MEDLINE (1946 to June 2015) and EMBASE (1980 to June 2015). We also searched LILACS, DARE, Health Technology Assessment, Web of Science and Scopus to June 2015. We checked the reference lists of all the studies identified by the above methods and contacted relevant authors and researchers in the field.

SELECTION CRITERIA

We included studies that: i) compared the results of blood PCR tests with the reference standard published by the European Organisation for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG); ii) reported data on false-positive, true-positive, false-negative and true-negative results of the diagnostic tests under investigation separately; and iii) evaluated the test(s) prospectively in cohorts of people from a relevant clinical population, defined as a group of individuals at high risk for invasive aspergillosis. Case-control studies were excluded from the analysis.

DATA COLLECTION AND ANALYSIS

Authors independently assessed quality and extracted data. For PCR assays, we evaluated the requirement for either one or two consecutive samples to be positive for diagnostic accuracy. We investigated heterogeneity by subgroup analyses. We plotted estimates of sensitivity and specificity from each study in receiver operating characteristics (ROC) space and constructed forest plots for visual examination of variation in test accuracy. We performed meta-analyses using the bivariate model to produce summary estimates of sensitivity and specificity.

MAIN RESULTS

Eighteen primary studies, corresponding to 19 cohorts and 22 data sets, published between 2000 and 2013 were included in the meta-analyses, with a median prevalence of IA (proven or probable) of 12.0% (range 2.5 to 30.8 %). The majority of people had received chemotherapy for a haematological malignancy or had undergone a hematopoietic stem cell transplant. Several PCR techniques were used among the included studies. The sensitivity and specificity of PCR for the diagnosis of IA varied according to the interpretative criteria used to define a test as positive. The mean sensitivity and specificity were 80.5% (95% CI; 73.0 to 86.3) and 78.5% (67.8 to 86.4) for a single positive test result, and 58.0% (36.5 to 76.8) and 96.2% (89.6 to 98.6) for two consecutive positive test results.

AUTHORS' CONCLUSIONS

PCR shows moderate diagnostic accuracy when used as screening tests for IA in high-risk patient groups. Importantly the sensitivity of the test confers a high negative predictive value (NPV) such that a negative test allows the diagnosis to be excluded. Consecutive positives show good specificity in diagnosis of IA and could be used to trigger radiological and other investigations or for pre-emptive therapy in the absence of specific radiological signs when the clinical suspicion of infection is high. When a single PCR positive test is used as diagnostic criterion for IA in a population of 100 people with a disease prevalence of 13.0% (overall mean prevalence), three people with IA would be missed (sensitivity 80.5%, 19.5% false negatives), and 19 people would be unnecessarily treated or referred for further tests (specificity of 78.5%, 21.5% false positives). If we use the two positive test requirement in a population with the same disease prevalence, it would mean that six IA people would be missed (sensitivity 58.0%, 42.1% false negatives) and three people would be unnecessarily treated or referred for further tests (specificity of 96.2%, 3.8% false positives). Galactomannan and PCR have good NPV for excluding disease but the low prevalence of disease limits the ability to rule in a diagnosis. The biomarkers are detecting different aspects of disease and the combination of both together is likely to be more useful.

Diagnostic Modalities for Invasive Mould Infections among Hematopoietic Stem Cell Transplant and Solid Organ Recipients: Performance Characteristics and Practical Roles in the Clinic

The morbidity and mortality of hematopoietic stem cell and solid organ transplant patients with invasive fungal infections (IFIs) remain high despite an increase in the number of effective antifungal agents. Early diagnosis leading to timely administration of antifungal therapy has been linked to better outcomes. Unfortunately, the diagnosis of IFIs remains challenging. The current gold standard for diagnosis is a combination of histopathology and culture, for which the sensitivity is <50%. Over the past two decades, a plethora of non-culture-based antigen and molecular assays have been developed and clinically validated. In this article, we will review the performance of the current commercially available non-cultural diagnostics and discuss their practical roles in the clinic.

Polymerase chain reaction blood tests for the diagnosis of invasive aspergillosis in immunocompromised people

BACKGROUND

Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mould infection in immunocompromised people. Early diagnosis of IA and prompt administration of appropriate antifungal treatment are critical to the survival of people with IA. Antifungal drugs can be given as prophylaxis or empirical therapy, instigated on the basis of a diagnostic strategy (the pre-emptive approach) or for treating established disease. Consequently there is an urgent need for research into both new diagnostic tools and drug treatment strategies. Newer methods such as polymerase chain reaction (PCR) to detect fungal nucleic acids are increasingly being investigated.

OBJECTIVES

To provide an overall summary of the diagnostic accuracy of PCR-based tests on blood specimens for the diagnosis of IA in immunocompromised people.

SEARCH METHODS

We searched MEDLINE (1946 to June 2015) and EMBASE (1980 to June 2015). We also searched LILACS, DARE, Health Technology Assessment, Web of Science and Scopus to June 2015. We checked the reference lists of all the studies identified by the above methods and contacted relevant authors and researchers in the field.

SELECTION CRITERIA

We included studies that: i) compared the results of blood PCR tests with the reference standard published by the European Organisation for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG); ii) reported data on false-positive, true-positive, false-negative and true-negative results of the diagnostic tests under investigation separately; and iii) evaluated the test(s) prospectively in cohorts of people from a relevant clinical population, defined as a group of individuals at high risk for invasive aspergillosis. Case-control studies were excluded from the analysis.

DATA COLLECTION AND ANALYSIS

Authors independently assessed quality and extracted data. For PCR assays, we evaluated the requirement for either one or two consecutive samples to be positive for diagnostic accuracy. We investigated heterogeneity by subgroup analyses. We plotted estimates of sensitivity and specificity from each study in receiver operating characteristics (ROC) space and constructed forest plots for visual examination of variation in test accuracy. We performed meta-analyses using the bivariate model to produce summary estimates of sensitivity and specificity.

MAIN RESULTS

Eighteen primary studies, corresponding to 19 cohorts and 22 data sets, published between 2000 and 2013 were included in the meta-analyses, with a median prevalence of IA (proven or probable) of 12.0% (range 2.5 to 30.8 %). The majority of people had received chemotherapy for a haematological malignancy or had undergone a hematopoietic stem cell transplant. Several PCR techniques were used among the included studies. The sensitivity and specificity of PCR for the diagnosis of IA varied according to the interpretative criteria used to define a test as positive. The mean sensitivity and specificity were 80.5% (95% CI; 73.0 to 86.3) and 78.5% (67.8 to 86.4) for a single positive test result, and 58.0% (36.5 to 76.8) and 96.2% (89.6 to 98.6) for two consecutive positive test results.

AUTHORS' CONCLUSIONS

PCR shows moderate diagnostic accuracy when used as screening tests for IA in high-risk patient groups. Importantly the sensitivity of the test confers a high negative predictive value (NPV) such that a negative test allows the diagnosis to be excluded. Consecutive positives show good specificity in diagnosis of IA and could be used to trigger radiological and other investigations or for pre-emptive therapy in the absence of specific radiological signs when the clinical suspicion of infection is high. When a single PCR positive test is used as diagnostic criterion for IA in a population of 100 people with a disease prevalence of 13.0% (overall mean prevalence), three people with IA would be missed (sensitivity 80.5%, 19.5% false negatives), and 19 people would be unnecessarily treated or referred for further tests (specificity of 78.5%, 21.5% false negatives). If we use the two positive test requirement in a population with the same disease prevalence, it would mean that six IA people would be missed (sensitivity 58.0%, 42.1% false negatives) and three people would be unnecessarily treated or referred for further tests (specificity of 96.2%, 3.8% false negatives). Galactamannan and PCR have good NPV for excluding disease but the low prevalence of disease limits the ability to rule in a diagnosis. The biomarkers are detecting different aspects of disease and the combination of both together is likely to be more useful.

Improved Standardization of the Bio-Rad Platelia Aspergillus Galactomannan Antigen Sandwich Enzyme Immunoassay Using the DS2 (Dynex) Enzyme-Linked Immunosorbent Assay (ELISA) Processing System

The galactomannan enzyme immunoassay (GM-EIA) is widely utilized for the diagnosis of invasive aspergillosis (IA). There is inconsistent reproducibility of results between centers when the assay is processed manually. Automation of EIAs can reduce variation. This study investigated the semiautomation of the GM-EIA on the DS2 (Dynex) platform in the following three stages: (i) DS2 GM-EIA method validation with experimental samples, (ii) DS2 retesting of case-defined clinical samples, and (iii) a 12-month audit of DS2 GM-EIA performance. In stage i, Bland-Altman analysis demonstrated a reduced variance between optical density index (ODI) values for samples processed on two DS2 platforms (mean difference, -0.02; limits of agreement [LOA], -0.19 to 0.14) compared with the variance between samples processed manually and on a DS2 platform (mean difference, 0.02; LOA, -0.25 to 0.3). In stage ii, 100% (14/14 samples) qualitative agreement was observed for serum samples from patients with IA, with no significant change in the ODI values when samples were processed on the DS2 platform. A significant decrease in ODI values was observed for control serum samples on the DS2 platform (difference, 0.01; P = 0.042). In stage iii, a significant reduction in the frequency of equivocal results, from 5.56% (136/2,443 samples) to 1.56% (15/961 samples), was observed after DS2 automation (difference, 4.0%; 95% confidence interval [CI], 2.7 to 5.2%; P < 0.01), with an equivalent increase in negative results. This study demonstrates that GM-EIA automation may reduce intersite variability. Automation does not have an impact on the repeatability of truly positive results but contributes to a reduction in false-positive (equivocal) GM-EIA results, reducing the need to retest a significant proportion of samples.

British Society for Medical Mycology best practice recommendations for the diagnosis of serious fungal diseases

Invasive fungal diseases are an important cause of morbidity and mortality in a wide range of patients, and early diagnosis and management are a challenge. We therefore did a review of the scientific literature to generate a series of key recommendations for the appropriate use of microbiological, histological, and radiological diagnostic methods for diagnosis of invasive fungal diseases. The recommendations emphasise the role of microscopy in rapid diagnosis and identification of clinically significant isolates to species level, and the need for susceptibility testing of all Aspergillus spp, if treatment is to be given. In this Review, we provide information to improve understanding of the importance of antigen detection for cryptococcal disease and invasive aspergillosis, the use of molecular (PCR) diagnostics for aspergillosis, and the crucial role of antibody detection for chronic and allergic aspergillosis. Furthermore, we consider the importance of histopathology reporting with a panel of special stains, and emphasise the need for urgent (<48 hours) and optimised imaging for patients with suspected invasive fungal infection. All 43 recommendations are auditable and should be used to ensure best diagnostic practice and improved outcomes for patients.

An overview of systematic reviews of diagnostic tests accuracy

The Cochrane Collaboration says that the Cochrane handbook for diagnostic test accuracy reviews (DTAR) is currently in development as per the Cochrane Collaboration. This implies that the methodology of systematic reviews (SR) of diagnostic test accuracy is still a matter of debate. At this point, comparison of methodologies for SR in case of interventions as against diagnostics would be helpful to understand DTAR.

PCR in diagnosis of invasive aspergillosis: a meta-analysis of diagnostic performance

Invasive aspergillosis is a difficult-to-diagnose infection with a high mortality rate that affects high-risk groups such as patients with neutropenia and hematologic malignancies. We performed a bivariate meta-analysis of diagnostic data for an Aspergillus sp. PCR assay with blood specimens from high-risk hematology patients. We included all studies involving human subjects that assessed the performance of any PCR assay for invasive aspergillosis in whole blood or serum and that used the European Organization for the treatment of Cancer/Mycoses Study Group criteria as a reference standard. Three investigators independently searched the literature for eligible studies and extracted the data. Out of a total of 37 studies, 25 met strict quality criteria and were included in our evidence synthesis. Twenty-five studies with 2,595 patients were analyzed. The pooled diagnostic performance of whole-blood and serum PCR assays was moderate, with a sensitivity and specificity of 84% (95% confidence interval [CI], 75 to 91%) and 76% (95% CI, 65 to 84%), respectively, suggesting that a positive or negative result is unable, on its own, to confirm or exclude a suspected infection. The performance of a PCR assay of serum was not significantly different from that of whole blood. Notably, at least two positive PCR test results were found to have a specificity of 95% and a sensitivity of 64% for invasive infection, achieving a high positive likelihood ratio of 12.8. Importantly, the European Aspergillus PCR Initiative (EAPCRI) recommendations improved the performance of the PCR even further when at least two positive specimens were used to define PCR positivity. In conclusion, two positive PCR results should be considered highly indicative of an active Aspergillus sp. infection. Use of the EAPCRI recommendations by clinical laboratories can further enhance PCR performance.