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

Diagnosis of invasive aspergillosis in haemato-oncology patients in a routine diagnostic setting

Invasive Aspergillosis (IA) is a potentially lethal infection in high-risk haemato-oncology patients. Since traditional diagnostic methods have many inherent challenges, Polymerase Chain Reaction (PCR) has been used to diagnose IA. This prospective study evaluated a commercial AsperGenius multiplex real-time PCR for its clinical utility in diagnosing IA compared with galactomannan (GM) testing serum samples from haemato-oncology patients with clinically suspected IA. A total of 107 patients were recruited between April 2022 and March 2023. Serum samples (n = 113) collected from those patients for the routine diagnosis by GM Enzyme Linked Immuno-Sorbent Assay (ELISA) were subjected to PCR. The patients were categorised into probable, possible, and no IA based on revised (2020) and previous (2008) European Organization for Research and Treatment of Cancer and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC-MSG) criteria. The performance characteristics of PCR and GM were calculated against the EORTC criteria by combining probable and possible cases as diseased groups. Among the 107 recruited patients, 93 were categorised into probable/possible IA (diseased group) and 14 into no IA group. The PCR was positive in 53 samples from 49 patients. The sensitivity and specificity of single positive PCR and GM were 51.61% [95% confidence interval, 41-62], 92.86% (66.1-99.8) and 26.88% (18.2-37.1), 92.86% (66.1-99.8), respectively. The combination-based strategy (GM and/or PCR positive) exhibited a moderate sensitivity of 62.37% (51-72.2) and a specificity of 85.71% (57.2-98.2). To conclude, the combined strategy of serum GM and/or PCR positivity, along with radiological findings that fulfilled the EORTC/MSG criteria, has improved the diagnosis of probable IA among high-risk haematological patients with clinically suspected IA.

ISCCM Position Statement on the Management of Invasive Fungal Infections in the Intensive Care Unit

Rationale

Invasive fungal infections (IFI) in the intensive care unit (ICU) are an emerging problem owing to the use of broad-spectrum antibiotics, immunosuppressive agents, and frequency of indwelling catheters. Timely diagnosis which is imperative to improve outcomes can be challenging. This position statement is aimed at understanding risk factors, providing a rational diagnostic approach, and guiding clinicians to optimize antifungal therapy.

Objectives

To update evidence on epidemiology, risk factors, diagnostic approach, antifungal initiation strategy, therapeutic interventions including site-specific infections and role of therapeutic drug monitoring in IFI in ICU and focus on some practice points relevant to these domains.

Methodology

A committee comprising critical care specialists across the country was formed and specific aspects of fungal infections and antifungal treatment were assigned to each member. They extensively reviewed the literature including the electronic databases and the international guidelines and cross-references. The information was shared and discussed over several meetings and position statements were framed to ensure their reliability and relevance in critical practice. The draft document was prepared after obtaining inputs and consensus from all the members and was reviewed by an expert in this field.

Results

The existing evidence on the management of IFI was updated and practice points were prepared under each subheading to enable critical care practitioners to streamline diagnosis and treatment strategies for patients in the ICU with additional detail on site-specific infections therapeutic drug monitoring.

Conclusion

This position statement attempts to address the management of IFI in immunocompetent and non-neutropenic ICU patients. The practice points should guide in optimization of the management of critically ill patients with suspected or proven fungal infections.

How to cite this article

Bhattacharya PK, Chakrabarti A, Sinha S, Pande R, Gupta S, Kumar AAK, et al. ISCCM Position Statement on the Management of Invasive Fungal Infections in the Intensive Care Unit. Indian J Crit Care Med 2024;28(S2):S20-S41.

Aspergillus endocarditis

Aspergillus endocarditis is a rare cause of fungal endocarditis caused by the hyaline mold Aspergillus. The disease most commonly occurs in persons who are immunosuppressed and has a high mortality. Clinical presentation is often with long standing fever, embolic manifestations, and often heart murmurs. Diagnosis of aspergillus endocarditis is often delayed due to the low propensity for Aspergillus to grow in blood culture. Aspergillus endocarditis is characterized by large vegetations and also by frequently being found on the walls of the heart and not on the valves and hence can be missed if not carefully looked for. Definitive diagnosis is often by a combination of microbiological culture and histopathological examination of obtained tissue. Ancillary serological tests like galactomannan assay and polymerase chain reaction also help in the diagnosis. Treatment of aspergillus endocarditis virtually always requires a combination of prolonged antifungal therapy and surgery to enable a cure for these patients.

Is there still a place for serum galactomannan in the diagnosis of invasive aspergillosis in children at high risk and under antifungal prophylaxis?

BACKGROUND

The performance of serum galactomannan (GM) for the diagnosis of invasive aspergillosis (IA) has been studied mainly in adults. Paediatric data are scarce and based on small and heterogeneous cohorts.

OBJECTIVE

To evaluate the performance of serum GM for the diagnosis of IA in a paediatric oncologic population at high risk of IA and to clarify the impact of antifungal prophylaxis on this test.

METHODS

We performed a retrospective study from January 2014 to December 2020 in the paediatric oncologic haematologic department of the University Hospital of Bordeaux. The diagnosis of IA was made using the recommendations of the EORTC and the MSGERC.

RESULTS

Among the 329 periods at high risk of IA in 222 patients, the prevalence of IA was 1.8% (3 proven and 3 probable IA). In the total population, the sensitivity, and the positive predictive value (PPV) were respectively 50% and 17.6%. Under antifungal prophylaxis, the sensitivity and PPV dropped, respectively, to 33.3% and 14.3%. In this group, the post-test probability of IA was 2% for a negative serum GM and only 14%.

CONCLUSION

In this large cohort of children at high risk of IA, the incidence of IA is low and the diagnostic performance of GM is poor, especially in the case of mould-active prophylaxis. Screening should be targeted rather than systematic and should be reserved for patients at highest risk for IA without mould-active prophylaxis. Combination with other tests such as Aspergillus PCR would increase the accuracy of GM in screening setting.

Utility of an in-house real-time PCR in whole blood samples as a minimally invasive method for early and accurate diagnosis of invasive mould infections

INTRODUCTION

Invasive mould infections (IMIs) are a leading cause of death in patients with compromised immune systems. Proven invasive mould infection requires detection of a fungus by histopathological analysis of a biopsied specimen, sterile culture, or fungal DNA amplification by PCR in tissue. However, the clinical performance of a PCR assay on blood samples taken from patients suspected of invasive mould disease has not been fully evaluated, particularly for the differential diagnosis of invasive aspergillosis (IA) and invasive Mucormycosis (IM).

OBJECTIVES

To assess the diagnostic utility of our previously validated in-house real-time PCR in blood samples for diagnosis of invasive aspergillosis and mucormycosis in patients with suspected invasive mould infection.

METHODS

All patients with suspected invasive mould infection were prospectively enrolled from May 2021 to July 2021. Conventional fungal diagnosis was performed using tissue and respiratory samples. In-house PCR was performed on blood samples and its diagnostic performance evaluated.

RESULTS

A total of 158 cases of suspected invasive mould infection were enrolled in the study. The sensitivity and specificity of in-house PCR performed on blood samples was found to be 92.5% and 81.4% respectively for diagnosis of probable IA, and 65% and 84.62% respectively for diagnosis of proven and probable IM. It was also able to detect 3 out of 5 cases of possible IM where no other microbiological evidence of IM was obtained.

CONCLUSIONS

This assay could be helpful in minimally invasive diagnosis of IMIs for patients in whom invasive sampling is not feasible, especially as a preliminary or screening test. It can help in early diagnosis, anticipating conventional laboratory confirmation by days or weeks. Possible correlation between fungal load and mortality can help in initiating aggressive treatment for patients with high initial fungal load.

Acute Invasive Pulmonary Aspergillosis: Clinical Presentation and Treatment

Among all clinical manifestations of pulmonary aspergillosis, invasive pulmonary aspergillosis (IPA) is the most acute presentation. IPA is caused by Aspergillus hyphae invading the pulmonary tissue, causing either tracheobronchitis and/or bronchopneumonia. The degree of fungal invasion into the respiratory tissue can be seen as a spectrum, going from colonization to deep tissue penetration with angio-invasion, and largely depends on the host's immune status. Patients with prolonged, severe neutropenia and patients with graft-versus-host disease are at particularly high risk. However, IPA also occurs in other groups of immunocompromised and nonimmunocompromised patients, like solid organ transplant recipients or critically ill patients with severe viral disease. While a diagnosis of proven IPA is challenging and often warranted by safety and feasibility, physicians must rely on a combination of clinical, radiological, and mycological features to assess the likelihood for the presence of IPA. Triazoles are the first-choice regimen, and the choice of the drug should be made on an individual basis. Adjunctive therapy such as immunomodulatory treatment should also be taken into account. Despite an improving and evolving diagnostic and therapeutic armamentarium, the burden and mortality of IPA still remains high. This review aims to give a comprehensive and didactic overview of the current knowledge and best practices regarding the epidemiology, clinical presentation, diagnosis, and treatment of acute IPA.

Microbiological Diagnosis of Pulmonary Aspergillus Infections

As microbiological tests play an important role in our diagnostic algorithms and clinical approach towards patients at-risk for pulmonary aspergillosis, a good knowledge of the diagnostic possibilities and especially their limitations is extremely important. In this review, we aim to reflect critically on the available microbiological diagnostic modalities for diagnosis of pulmonary aspergillosis and formulate some future prospects. Timely start of adequate antifungal treatment leads to a better patient outcome, but overuse of antifungals should be avoided. Current diagnostic possibilities are expanding, and are mainly driven by enzyme immunoassays and lateral flow device tests for the detection of Aspergillus antigens. Most of these tests are directed towards similar antigens, but new antibodies towards different targets are under development. For chronic forms of pulmonary aspergillosis, anti-Aspergillus IgG antibodies and precipitins remain the cornerstone. More studies on the possibilities and limitations of molecular testing including targeting resistance markers are ongoing. Also, metagenomic next-generation sequencing is expanding our future possibilities. It remains important to combine different test results and interpret them in the appropriate clinical context to improve performance. Test performances may differ according to the patient population and test results may be influenced by timing, the tested matrix, and prophylactic and empiric antifungal therapy. Despite the increasing armamentarium, a simple blood or urine test for the diagnosis of aspergillosis in all patient populations at-risk is still lacking. Research on diagnostic tools is broadening from a pathogen focus on biomarkers related to the patient and its immune system.

Clinical Implementation of β-Tubulin Gene-Based Aspergillus Polymerase Chain Reaction for Enhanced Aspergillus Diagnosis in Patients with Hematologic Diseases: A Prospective Observational Study

The β-tubulin (benA) gene is a promising target for the identification of Aspergillus species. Assessment of the clinical implementation and performance of benA gene-based Aspergillus polymerase chain reaction (PCR) remains warranted. In this study, we assessed the analytical performance of the BenA probe PCR in comparison with the Aspergenius kit. We prospectively collected bronchoalveolar lavage (BAL) fluid via diagnostic bronchoscopy from adult patients with hematologic diseases. BenA gene-based multiplex real-time PCR and sequential melting temperature analysis were performed to detect the azole resistance of Aspergillus fumigatus. In total, 76 BAL fluids in 75 patients suspicious of invasive pulmonary aspergillosis (IPA) were collected. Before the application of PCR, the prevalence of proven and probable IPA was 32.9%. However, after implementing the benA gene-based PCR, 15.8% (12 out of 76) of potential IPA cases were reclassified as probable IPA. The analytical performance of the BenA probe PCR in BAL samples was comparable to that of the Aspergenius kit. The diagnostic performance was as follows: sensitivity, 52.0%; specificity, 64.7%; positive predictive value, 41.9%; negative predictive value, 73.3%; positive likelihood ratio, 1.473; and negative likelihood ratio, 0.741. Moreover, benA gene-based Aspergillus PCR discriminated all major sections of Aspergillus, including cryptic species such as Aspergillus tubingensis. Sequential melting temperature analysis successfully detected 2 isolates (15.4%) of A. fumigatus carrying resistant mutations. BenA gene-based Aspergillus PCR with melting temperature analysis enhances diagnostic accuracy and detects not only cryptic species but also resistant mutations of A. fumigatus. It shows promise for clinical applications in the diagnosis of IPA.

Superior Accuracy of Aspergillus Plasma Cell-Free DNA Polymerase Chain Reaction Over Serum Galactomannan for the Diagnosis of Invasive Aspergillosis

BACKGROUND

Invasive aspergillosis (IA) in immunocompromised hosts carries high morbidity and mortality. Diagnosis is often delayed because definitive diagnosis requires invasive specimen collection, while noninvasive testing with galactomannan is moderately accurate. Plasma cell-free DNA polymerase chain reaction (cfDNA PCR) represents a novel testing modality for the noninvasive diagnosis of invasive fungal disease (IFD). We directly compared the performance of Aspergillus plasma cfDNA PCR with serum galactomannan for the diagnosis of IA during routine clinical practice.

METHODS

We conducted a retrospective study of all patients with suspected IFD who had Aspergillus plasma cfDNA PCR testing at Stanford Health Care from 1 September 2020 to 30 October 2022. Patients were categorized into proven, probable, possible, and no IA based on the EORTC/MSG definitions. Primary outcomes included the clinical sensitivity and specificity for Aspergillus plasma cfDNA PCR and galactomannan.

RESULTS

Overall, 238 unique patients with Aspergillus plasma cfDNA PCR test results, including 63 positives and 175 nonconsecutive negatives, were included in this study. The majority were immunosuppressed (89.9%) with 22.3% 30-day all-cause mortality. The overall sensitivity and specificity of Aspergillus plasma cfDNA PCR were 86.0% (37 of 43; 95% confidence interval [CI], 72.7-95.7) and 93.1% (121 of 130; 95% CI, 87.4-96.3), respectively. The sensitivity and specificity of serum galactomannan in hematologic malignancies/stem cell transplants were 67.9% (19 of 28; 95% CI, 49.3-82.1) and 89.8% (53 of 59; 95% CI, 79.5-95.3), respectively. The sensitivity of cfDNA PCR was 93.0% (40 of 43; 95% CI, 80.9-98.5) in patients with a new diagnosis of IA.

CONCLUSIONS

Aspergillus plasma cfDNA PCR represents a more sensitive alternative to serum galactomannan for noninvasive diagnosis of IA.

An Overview of Systematic Reviews of Polymerase Chain Reaction (PCR) for the Diagnosis of Invasive Aspergillosis in Immunocompromised People: A Report of the Fungal PCR Initiative (FPCRI)-An ISHAM Working Group

This overview of reviews (i.e., an umbrella review) is designed to reappraise the validity of systematic reviews (SRs) and meta-analyses related to the performance of Aspergillus PCR tests for the diagnosis of invasive aspergillosis in immunocompromised patients. The methodological quality of the SRs was assessed using the AMSTAR-2 checklist; the quality of the evidence (QOE) within each SR was appraised following the GRADE approach. Eight out of 12 SRs were evaluated for qualitative and quantitative assessment. Five SRs evaluated Aspergillus PCR on bronchoalveolar lavage fluid (BAL) and three on blood specimens. The eight SRs included 167 overlapping reports (59 evaluating PCR in blood specimens, and 108 in BAL), based on 107 individual primary studies (98 trials with a cohort design, and 19 with a case-control design). In BAL specimens, the mean sensitivity and specificity ranged from 0.57 to 0.91, and from 0.92 to 0.97, respectively (QOE: very low to low). In blood specimens (whole blood or serum), the mean sensitivity ranged from 0.57 to 0.84, and the mean specificity from 0.58 to 0.95 (QOE: low to moderate). Across studies, only a low proportion of AMSTAR-2 critical domains were unmet (1.8%), demonstrating a high quality of methodological assessment. Conclusions. Based on the overall methodological assessment of the reviews included, on average we can have high confidence in the quality of results generated by the SRs.

Clinical Evaluation of Polymerase Chain Reaction Coupled with Quantum Dot Fluorescence Analysis for Diagnosis of Candida Infection in Vulvovaginal Candidiasis Practice

Purpose

Time-consuming culture methods and wet-mount microscopy (WMM) with low sensitivity have difficulties in diagnosing Vulvovaginal candidiasis (VVC). Rapid and highly sensitive polymerase chain reaction coupled with quantum dot fluorescence analysis (PCR-QDFA) for the diagnosis of VVC has not been reported to date. This study was the first to evaluate the performance of PCR-QDFA for diagnosis of Candida strains in the leukorrhea samples from patients with suspected VVC.

Patients and Methods

Leukorrhea samples from all visited patients were taken from the vagina using vaginal swabs by clinicians. We evaluated patients admitted with suspected VVC who completed WMM for diagnosis and reported the diagnostic effectiveness of PCR-QDFA and Candida culture (gold standard) when testing leucorrhea samples.

Results

A total of 720 leukorrhea samples from 387 VVC-positive patients and 333 VVC-negative patients were included in this study. Of the 387 leukorrhea samples from the VVC-positive patients, 391 Candida strains were identified by culture. 99.23% (388/391) Candida strains were included in the PCR-QDFA list. The 388 Candida strains belonged to four different species of Candida, including C. albicans (n = 273, 70.36%), C. glabrata (n = 85, 21.91%), C. tropicalis (n = 16, 4.12%), and C. krusei (n = 14, 3.61%). PCR-QDFA diagnosed Candida strains in 340/384 (88.54%) of the leucorrhea samples with Candida strains infection. The sensitivity of PCR-QDFA for C. albicans, C. glabrata, C. tropicalis, and C. krusei was 89.01%, 85.88%, 81.25% and 92.86%, respectively. The specificity of PCR-QDFA for C. albicans, C. glabrata, C. tropicalis and C. krusei was 93.69%, 99.37%, 99.71%, and 99.57%, respectively.

Conclusion

The highly sensitive and specific PCR-QDFA technique can be exploited as a rapid (approximately 4 h) diagnostic tool for common Candida strains of leucorrhea samples from patients with suspected VVC.

Performance of a Real-Time PCR Assay for the Detection of Five Candida Species in Blood Samples from ICU Patients at Risk of Candidemia

The gold standard for diagnosing invasive candidiasis still relies on blood cultures, which are inefficient and time-consuming to analyze. We developed an in-house qPCR assay to identify the 5 major Candida species in 78 peripheral blood (PB) samples from ICU patients at risk of candidemia. Blood cultures and (1,3)-β-D-glucan (BDG) testing were performed concurrently to evaluate the performance of the qPCR. The qPCR was positive for DNA samples from all 20 patients with proven candidemia (positive PB cultures), showing complete concordance with Candida species identification in blood cultures, except for detection of dual candidemia in 4 patients, which was missed by blood cultures. Additionally, the qPCR detected Candida species in six DNA samples from patients with positive central venous catheters blood (CB) but negative PB cultures. BDG values were similarly high in these six samples and the ones with proven candidemia, strongly suggesting the diagnosis of a true candidemia episode despite the negative PB cultures. Samples from patients neither infected nor colonized yielded negative results in both the qPCR and BDG testing. Our qPCR assay was at least as sensitive as blood cultures, but with a shorter turnaround time. Furthermore, negative results from the qPCR provided strong evidence for the absence of candidemia caused by the five major Candida species.

Invasive Pulmonary Aspergillosis in Coronavirus Disease 2019 Patients Lights and Shadows in the Current Landscape

Invasive pulmonary aspergillosis (IPA) presents a known risk to critically ill patients with SARS-CoV-2; quantifying the global burden of IPA in SARS-CoV-2 is extremely challenging. The true incidence of COVID-19-associated pulmonary aspergillosis (CAPA) and the impact on mortality is difficult to define because of indiscriminate clinical signs, low culture sensitivity and specificity and variability in clinical practice between centers. While positive cultures of upper airway samples are considered indicative for the diagnosis of probable CAPA, conventional microscopic examination and qualitative culture of respiratory tract samples have quite low sensitivity and specificity. Thus, the diagnosis should be confirmed with serum and BAL GM test or positive BAL culture to mitigate the risk of overdiagnosis and over-treatment. Bronchoscopy has a limited role in these patients and should only be considered when diagnosis confirmation would significantly change clinical management. Varying diagnostic performance, availability, and time-to-results turnaround time are important limitations of currently approved biomarkers and molecular assays for the diagnosis of IA. The use of CT scans for diagnostic purposes is controversial due to practical concerns and the complex character of lesions presented in SARS-CoV-2 patients. The key objective of management is to improve survival by avoiding misdiagnosis and by initiating early, targeted antifungal treatment. The main factors that should be considered upon selection of treatment options include the severity of the infection, concomitant renal or hepatic injury, possible drug interactions, requirement for therapeutic drug monitoring, and cost of therapy. The optimal duration of antifungal therapy for CAPA is still under debate.

The Use of Host Biomarkers for the Management of Invasive Fungal Disease

Invasive fungal disease (IFD) causes severe morbidity and mortality, and the number of IFD cases is increasing. Exposure to opportunistic fungal pathogens is inevitable, but not all patients with underlying diseases increasing susceptibility to IFD, develop it. IFD diagnosis currently uses fungal biomarkers and clinical risk/presentation to stratify high-risk patients and classifies them into possible, probable, and proven IFD. However, the fungal species responsible for IFD are highly diverse and present numerous diagnostic challenges, which culminates in the empirical anti-fungal treatment of patients at risk of IFD. Recent studies have focussed on host-derived biomarkers that may mediate IFD risk and can be used to predict, and even identify IFD. The identification of novel host genetic variants, host gene expression changes, and host protein expression (cytokines and chemokines) associated with increased risk of IFD has enhanced our understanding of why only some patients at risk of IFD actually develop disease. Furthermore, these host biomarkers when incorporated into predictive models alongside conventional diagnostic techniques enhance predictive and diagnostic results. Once validated in larger studies, host biomarkers associated with IFD may optimize the clinical management of populations at risk of IFD. This review will summarise the latest developments in the identification of host biomarkers for IFD, their use in predictive modelling and their potential application/usefulness for informing clinical decisions.

Diagnosis and Treatment of Invasive Mold Diseases

Although invasive fungal diseases are relatively less common than superficial diseases, there has been an overall increase in their incidence. Here, I review the epidemiology, diagnosis, and treatment of invasive mold diseases (IMDs) such as aspergillosis, mucormycosis, hyalohyphomycosis, and phaeohyphomycosis. Histopathologic demonstration of tissue invasion by hyphae or recovery of mold by the culture of a specimen obtained by a sterile procedure provides definitive evidence of IMD. If IMD cannot be confirmed through invasive procedures, IMD can be diagnosed through clinical criteria such as the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Instituteof Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) definitions. For initial primary therapy of invasive aspergillosis, voriconazole or isavuconazole is recommended and lipid formulations of amphotericin B are useful primary alternatives. Echinocandins are representative antifungal agents for salvage therapy. Treatment of invasive mucormycosis involves a combination of urgent surgical debridement of involved tissues and antifungal therapy. Lipid formulations of amphotericin B are the drug of choice for initial therapy. Isavuconazole or posaconazole can be used as salvage or step-down therapy. IMDs other than aspergillosis and mucormycosis include hyalohyphomycosis and phaeohyphomycosis, for which there is no standard therapy and the treatment depends on the clinical disease and status of the patient.

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.

Noninvasive Testing and Surrogate Markers in Invasive Fungal Diseases

Invasive fungal infections continue to increase as at-risk populations expand. The high associated morbidity and mortality with fungal diseases mandate the continued investigation of novel antifungal agents and diagnostic strategies that include surrogate biomarkers. Biologic markers of disease are useful prognostic indicators during clinical care, and their use in place of traditional survival end points may allow for more rapid conduct of clinical trials requiring fewer participants, decreased trial expense, and limited need for long-term follow-up. A number of fungal biomarkers have been developed and extensively evaluated in prospective clinical trials and small series. We examine the evidence for these surrogate biomarkers in this review and provide recommendations for clinicians and regulatory authorities.

Cerebral vasculitis due to Aspergillus spp. in immunocompromised patients: literature review

OBJECTIVES

Invasive aspergillosis is a threat for immunocompromised patients. We present a case series of aggressive cerebral vasculitis caused by Aspergillus spp. infection in immunocompromised patients.

METHODS

We present a retrospective case series of three autopsy-proven invasive cerebral aspergillosis with diffuse vasculitis affecting large caliber cerebral vessels.

RESULTS

Three patients were immunosuppressed: one on rituximab, one on corticosteroids, and one with a renal transplant. Two of these patients were diagnosed with cerebral aspergillosis on postmortem.

CONCLUSION

Aspergillus cerebral vasculitis is a rare form of invasive aspergillosis that should be considered in an immunocompromised individual with suggestive lesions on imaging. It should be suspected as a possible cause of aseptic neutrophil meningitis.

Faster infection diagnostics for intensive care unit (ICU) patients

INTRODUCTION

: The patient admitted to intensive care units (ICU) is critically ill, to some extent immunosuppressed, with a high risk of infection, sometimes by multidrug-resistant microorganisms. In this context, the intensivist expects from the microbiology service quick and understandable information so that appropriate antimicrobial treatment for that particular patient and infection can be initiated.

AREAS COVERED

: In this review of recent literature (2015-2021), we identified diagnostic methods for the most prevalent infections in these patients through a search of the databases Pubmed, evidence-based medicine online, York University reviewers group, Cochrane, MBE-Trip, and Sumsearch using the terms: adult, clinical laboratory techniques, critical care, early diagnosis, microbiology, molecular diagnostic techniques, spectrometry and metagenomics.

EXPERT OPINION

: There has been an exponential surge in diagnostic systems used directly on blood and other samples to expedite microbial identification and antimicrobial susceptibility testing of pathogens. Few studies have thus far assessed their clinical impact; final outcomes will also depend on preanalytical and post-analytical factors. Besides, many of the resistance mechanisms cannot yet be detected with molecular techniques, which impairs the prediction of the actual resistance phenotype.

Nonetheless, this is an exciting field with much yet to explore.

An overview of using fungal DNA for the diagnosis of invasive mycoses

INTRODUCTION

Fungal PCR has undergone considerable standardization and together with the availability of commercial assays, external quality assessment schemes and extensive performance validation data, is ready for widespread use for the screening and diagnosis of invasive fungal disease (IFD).

AREAS COVERED

Drawing on the experience and knowledge of the leads of the various working parties of the Fungal PCR initiative, this review will address general considerations concerning the use of molecular tests for the diagnosis of IFD, before focussing specifically on the technical and clinical aspects of molecular testing for the main causes of IFD and recent technological developments.

EXPERT OPINION

For infections caused by Aspergillus, Candida and Pneumocystis jirovecii, PCR testing is recommended, combination with serological testing will likely enhance the diagnosis of these diseases. For other IFD (e.g. Mucormycosis) molecular diagnostics, represent the only non-classical mycological approach towards diagnoses and continued performance validation and standardization has improved confidence in such testing. The emergence of antifungal resistance can be diagnosed, in part, through molecular testing. Next-generation sequencing has the potential to significantly improve our understanding of fungal phylogeny, epidemiology, pathogenesis, mycobiome/microbiome and interactions with the host, while identifying novel and existing mechanisms of antifungal resistance and novel diagnostic/therapeutic targets.

Liquid Biopsy for Invasive Mold Infections in Hematopoietic Cell Transplant Recipients With Pneumonia Through Next-Generation Sequencing of Microbial Cell-Free DNA in Plasma

BACKGROUND

Noninvasive diagnostic options are limited for invasive mold infections (IMIs). We evaluated the performance of a plasma microbial cell-free DNA sequencing (mcfDNA-Seq) test for diagnosing pulmonary IMI after hematopoietic cell transplant (HCT).

METHODS

We retrospectively assessed the diagnostic performance of plasma mcfDNA-Seq next-generation sequencing in 114 HCT recipients with pneumonia after HCT who had stored plasma obtained within 14 days of diagnosis of proven/probable Aspergillus IMI (n = 51), proven/probable non-Aspergillus IMI (n = 24), possible IMI (n = 20), and non-IMI controls (n = 19). Sequences were aligned to a database including >400 fungi. Organisms above a fixed significance threshold were reported.

RESULTS

Among 75 patients with proven/probable pulmonary IMI, mcfDNA-Seq detected ≥1 pathogenic mold in 38 patients (sensitivity, 51% [95% confidence interval {CI}, 39%-62%]). When restricted to samples obtained within 3 days of diagnosis, sensitivity increased to 61%. McfDNA-Seq had higher sensitivity for proven/probable non-Aspergillus IMI (sensitivity, 79% [95% CI, 56%-93%]) compared with Aspergillus IMI (sensitivity, 31% [95% CI, 19%-46%]). McfDNA-Seq also identified non-Aspergillus molds in an additional 7 patients in the Aspergillus subgroup and Aspergillus in 1 patient with possible IMI. Among 19 non-IMI pneumonia controls, mcfDNA-Seq was negative in all samples, suggesting a high specificity (95% CI, 82%-100%) and up to 100% positive predictive value (PPV) with estimated negative predictive values (NPVs) of 81%-99%. The mcfDNA-Seq assay was complementary to serum galactomannan index testing; in combination, they were positive in 84% of individuals with proven/probable pulmonary IMI.

CONCLUSIONS

Noninvasive mcfDNA-Seq had moderate sensitivity and high specificity, NPV, and PPV for pulmonary IMI after HCT, particularly for non-Aspergillus species.

Aspergillus fumigatus and aspergillosis: From basics to clinics

The airborne fungus Aspergillus fumigatus poses a serious health threat to humans by causing numerous invasive infections and a notable mortality in humans, especially in immunocompromised patients. Mould-active azoles are the frontline therapeutics employed to treat aspergillosis. The global emergence of azole-resistant A. fumigatus isolates in clinic and environment, however, notoriously limits the therapeutic options of mould-active antifungals and potentially can be attributed to a mortality rate reaching up to 100 %. Although specific mutations in CYP 51A are the main cause of azole resistance, there is a new wave of azole-resistant isolates with wild-type CYP 51A genotype challenging the efficacy of the current diagnostic tools. Therefore, applications of whole-genome sequencing are increasingly gaining popularity to overcome such challenges. Prominent echinocandin tolerance, as well as liver and kidney toxicity posed by amphotericin B, necessitate a continuous quest for novel antifungal drugs to combat emerging azole-resistant A. fumigatus isolates. Animal models and the tools used for genetic engineering require further refinement to facilitate a better understanding about the resistance mechanisms, virulence, and immune reactions orchestrated against A. fumigatus. This review paper comprehensively discusses the current clinical challenges caused by A. fumigatus and provides insights on how to address them.

Update on Non-Culture-Based Diagnostics for Invasive Fungal Disease

Diagnostic tests for fungi provide the mycological evidence to strengthen diagnosis of invasive fungal disease. Conventional microbiology and histopathology have their limitations. Recognizing this, there have been attempts at developing new methods to improve yield of diagnosing invasive fungal disease (IFD). The recent focus has been on non-culture-based antigen detection and molecular methods. The use of antigen detection of IFD through 1,3-β-D-glucan and galactomannan assay have been expanded, followed by development of lateral flow assays, and in combination with other diagnostic modalities to further increase diagnostic yield. The molecular diagnostic front has seen initiatives to standardize polymerase chain reaction methodologies to detect fungi and anti-fungal resistance, new platforms such as the T2Candida Biosystems and foray into fungal metagenomics. As these newer assays undergo stringent validation before incorporation into the diagnostic algorithm, the clinician needs to be mindful of their bedside utility as well as their limitation.

A simple high-volume culture technique-Good substitute for polymerase chain reaction for the detection of Aspergillus species in bronchoalveolar lavage samples

BACKGROUND

Aspergillus species is the most common agent of invasive pulmonary fungal disease. Culture-based diagnosis considered as gold standard is limited by the fungal load in samples. Detection of Aspergillus by polymerase chain reaction (PCR) has been included as a diagnostic criterion by European Organisation for Research and Treatment of Cancer (EORTC). Most routine laboratories lack facilities for molecular diagnosis. Better yield using high-volume culture (HVC) technique has been reported. Studies have not compared HVC and PCR for detection of Aspergillus species in respiratory samples from patients with suspected invasive pulmonary Aspergillosis (IPA) not on antifungal therapy.

OBJECTIVE

This pilot study compared HVC and PCR for the detection of Aspergillus species in respiratory samples from treatment naïve patients.

METHODS

Bronchoalveolar lavage (BAL) samples from 30 patients with clinical suspicion of IPA were evaluated. Direct microscopy, culture both conventional (CC) and HVC and qualitative Pan Aspergillus PCR were performed. Latent class model was used for statistical analysis.

RESULTS

Sensitivity of HVC (100%) was better compared with CC (60%) and comparable to that of PCR (100%). Specificities of CC, HVC and PCR were 100%, 100% and 25%, respectively.

CONCLUSION

High-volume culture is a simple cost-effective technique with a high sensitivity and specificity. It can be easily introduced in routine microbiology laboratories. In centres with the availability of infrastructure for molecular analysis, Aspergillus PCR with other mycological techniques can be used for better diagnosis and management of patients with IPA.

Recognition of Diagnostic Gaps for Laboratory Diagnosis of Fungal Diseases: Expert Opinion from the Fungal Diagnostics Laboratories Consortium (FDLC)

Fungal infections are a rising threat to our immunocompromised patient population, as well as other nonimmunocompromised patients with various medical conditions. However, little progress has been made in the past decade to improve fungal diagnostics. To jointly address this diagnostic challenge, the Fungal Diagnostics Laboratory Consortium (FDLC) was recently created. The FDLC consists of 26 laboratories from the United States and Canada that routinely provide fungal diagnostic services for patient care. A survey of fungal diagnostic capacity among the 26 members of the FDLC was recently completed, identifying the following diagnostic gaps: lack of molecular detection of mucormycosis; lack of an optimal diagnostic algorithm incorporating fungal biomarkers and molecular tools for early and accurate diagnosis of Pneumocystis pneumonia, aspergillosis, candidemia, and endemic mycoses; lack of a standardized molecular approach to identify fungal pathogens directly in formalin-fixed paraffin-embedded tissues; lack of robust databases to enhance mold identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; suboptimal diagnostic approaches for mold blood cultures, tissue culture processing for Mucorales, and fungal respiratory cultures for cystic fibrosis patients; inadequate capacity for fungal point-of-care testing to detect and identify new, emerging or underrecognized, rare, or uncommon fungal pathogens; and performance of antifungal susceptibility testing. In this commentary, the FDLC delineates the most pressing unmet diagnostic needs and provides expert opinion on how to fulfill them. Most importantly, the FDLC provides a robust laboratory network to tackle these diagnostic gaps and ultimately to improve and enhance the clinical laboratory's capability to rapidly and accurately diagnose fungal infections.

Diagnostic performance of real-time polymerase chain reaction assay on blood for invasive aspergillosis and mucormycosis

OBJECTIVES

This study aimed to evaluate the diagnostic usefulness of real-time (RT) polymerase chain reaction (PCR) on blood samples for diagnosis of invasive aspergillosis and mucormycosis in patients with suspected invasive mould infection.

METHODS

Adult patients with suspected invasive mould infection were prospectively enrolled at a tertiary referral hospital in Seoul, South Korea between 2017 and 2020. Standard tests for diagnosis of invasive mould infection and RT-PCR for Aspergillus, Mucor and Rhizopus using blood samples were performed. We evaluated the diagnostic performance of RT-PCR tests in patients diagnosed with proven and probable invasive aspergillosis or mucormycosis infection, according to the modified definitions of the EORTC/MSG 2019.

RESULTS

A total of 102 patients with suspected invasive mould infection were enrolled. Of these patients, 46 (45%) were classified as having proven (n = 13) or probable (n = 33) invasive aspergillosis, 21 (21%) as proven (n = 17) or probable (n = 4) invasive mucormycosis and 18 (18%) as possible invasive mould infection. The remaining 13 (13%) were classified as not having invasive mould infection. Patients with possible invasive mould infection (n = 18) and coinfection of aspergillosis and mucormycosis (n = 4) were excluded from the final analysis. The sensitivity and specificity of the Aspergillus PCR were 54.3% ([25/46], 95% confidence interval [CI]: 40.2-67.9%) and 94.1% ([32/34], 95% CI: 80.9-98.4%), respectively. The sensitivity and specificity of the Mucor or Rhizopus PCR were 57.1% ([12/21], 95% CI: 36.6-75.5%) and 76.3% ([45/59], 95% CI: 64.0-85.3), respectively.

CONCLUSIONS

Our study suggests that blood PCR can be a useful adjunct test for diagnosing patients with suspected invasive mould infection.

Aspergillus Polymerase Chain Reaction-An Update on Technical Recommendations, Clinical Applications, and Justification for Inclusion in the Second Revision of the EORTC/MSGERC Definitions of Invasive Fungal Disease

Aspergillus polymerase chain reaction testing of blood and respiratory samples has recently been included in the second revision of the EORTC/MSGERC definitions for classifying invasive fungal disease. This is a result of considerable efforts to standardize methodology, the availability of commercial assays and external quality control programs, and additional clinical validation. This supporting article provides both clinical and technical justifications for its inclusion while also summarizing recent advances and likely future developments in the molecular diagnosis of invasive aspergillosis.

Performance, Correlation and Kinetic Profile of Circulating Serum Fungal Biomarkers of Invasive Aspergillosis in High-Risk Patients with Hematologic Malignancies

As conventional microbiological documentation of invasive aspergillosis (IA) is difficult to obtain, serum fungal biomarkers are important adjunctive diagnostic tools. Positivity rates and the kinetic profiles of galactomannan (GM), 1,3-β-D-glucan (BDG) and Aspergillus DNA (PCR) were studied in high-risk patients with hematologic malignancies. GM, BDG and PCR data from serial serum specimens (n = 240) from 93 adult hematology patients with probable (n = 8), possible (n = 25) and no (n = 60) IA were retrospectively analyzed. Positivity rates and sensitivity/specificity/positive/negative predictive values (NPV) of each fungal biomarker alone and in combination were estimated. The three markers were compared head-to-head and correlated with various biochemical, demographic and patient characteristics. The positivity rates for patients with probable/possible/no IA were 88%/8%/0% for GM (X² = 55, p < 0.001), 62%/46%/35% for BDG (X² = 2.5, p = 0.29), 62%/33%/27% for PCR (X² = 3.9, p = 0.15), 50%/4%/0% for GM + BDG and GM + PCR (X² = 31, p < 0.001), 50%/8%/22% for BDG + PCR (X² = 6.5, p = 0.038) and 38%/4%/0% for GM + BDG + PCR (X² = 21, p < 0.001). Higher agreement (76%) and negative correlation (r_s = −0.47, p = 0.0017) was found between GM index and PCR Ct values. The sensitivity and NPV was 45–55% and 90–92% when biomarkers assessed alone and increased to 75–90% and 93–97%, respectively when combined. Weak significant correlations were found between GM, PCR and BDG results with renal/liver function markers (r = 0.11–0.57) with most GM+ and PCR+ samples found in the first and second week of clinical assessment, respectively and BDG later on. Different positivity rates, time profiles and performances were found for the three biomarkers advocating the combination of GM with PCR for the early diagnosis of IA, whereas the high NPV of combined biomarkerscould help excluding IA.

A Prospective Multicenter Cohort Surveillance Study of Invasive Aspergillosis in Patients with Hematologic Malignancies in Greece: Impact of the Revised EORTC/MSGERC 2020 Criteria

Data concerning the incidence of invasive aspergillosis (IA) in high-risk patients in Greece are scarce, while the impact of the revised 2020 EORTC/MSGERC consensus criteria definitions on the reported incidence rate of IA remains unknown. A total of 93 adult hematology patients were screened for IA for six months in four tertiary care Greek hospitals. Serial serum specimens (n = 240) the sample was considered negative by PCR were collected twice-weekly and tested for galactomannan (GM) and Aspergillus DNA (PCR) detection. IA was defined according to both the 2008 EORTC/MSG and the 2020 EORTC/MSGERC consensus criteria. Based on the 2008 EORTC/MSG criteria, the incidence rates of probable and possible IA was 9/93 (10%) and 24/93 (26%), respectively, while no proven IA was documented. Acute myeloid leukemia was the most (67%) common underlying disease with most (82%) patients being on antifungal prophylaxis/treatment. Based on the new 2020 EORTC/MSGERC criteria, 2/9 (22%) of probable and 1/24 (4%) of possible cases should be reclassified as possible and probable, respectively. The episodes of probable IA were reduced by 33% when GM alone and 11% when GM + PCR were used as mycological criterion. The incidence rate of IA in hematology patients was 10%. Application of the 2020 EORTC/MSGERC updated criteria results in a reduction in the classification of probable IA particularly when PCR is not available.

The Aspergillus Lateral Flow Assay for the Diagnosis of Invasive Aspergillosis: an Update

Purpose of Review

To review the data on the Aspergillus lateral flow assay for the diagnosis of invasive Aspergillosis.

Recent Findings

Aspergillus spp. cause a wide spectrum of disease with invasive aspergillosis (IA) as its most severe manifestation. Early and reliable diagnosis of disease is crucial to decrease associated morbidity and mortality, and enable prompt initiation of treatment for IA. Most recently, non-culture-based tests, such as Aspergillus galactomannan (GM), have been useful in early identification and treatment of patients with IA. However, cost, turnaround time, and variable performance indifferent populations at risk for IA remain significant drawbacks to the use of this test. Several diagnostic tests for IA have been developed, including the sōna Aspergillus GM Lateral flow assay (GM-LFA) rapid test.

Summary

The GM-LFA has shown excellent performance for the diagnosis of IA in patients with hematologic malignancy and may be a viable option for settings where ELISA GM testing is not feasible. Further evaluation of the GM-LFA in the non-hematology setting is ongoing, including in solid organ transplant recipients and patients in the intensive care unit.

Emerging Microbiology Diagnostics for Transplant Infections: On the Cusp of a Paradigm Shift

In light of the heightened risk for infection associated with solid organ and hematopoietic stem cell transplantation, rapid and accurate microbiology diagnostics are essential to the practice of transplant clinicians, including infectious diseases specialists. In the last decade, diagnostic microbiology has seen a shift toward culture-independent techniques including single-target and multiplexed molecular testing, mass-spectrometry, and magnetic resonance-based methods which have together greatly expanded the array of pathogens identified, increased processing speed and throughput, allowed for detection of resistance determinants, and ultimately improved the outcomes of infected transplant recipients. More recently, a newer generation of diagnostics with immense potential has emerged, including multiplexed molecular panels directly applicable to blood and blood culture specimens, next-generation metagenomics, and gas chromatography mass spectrometry. Though these methods have some recognized drawbacks, many have already demonstrated improved sensitivity and a positive impact on clinical outcomes in transplant and immunocompromised patients.

Point-of-care diagnostics for invasive aspergillosis: nearing the finish line

INTRODUCTION

The spectrum of disease caused by Aspergillus spp. is dependent on the immune system of the host, with invasive aspergillosis (IA) its most severe manifestation. Early and reliable diagnosis of Aspergillus disease is important to decrease associated morbidity and mortality from IA.

AREAS COVERED

The following review searched Pub Med for literature published since 2007 and will give an update on the current point-of-care diagnostic strategies for the diagnosis of IA, discuss needed areas of improvement for these tests, and future directions.

EXPERT OPINION

Several new diagnostic tests for IA - including point-of-care tests - are now available to complement conventional galactomannan (GM) testing. In particular, the Aspergillus-specific Lateral Flow Device (LFD) test and the sōna Aspergillus GM Lateral Flow Assay (LFA) are promising for the diagnosis of IA in patients with hematologic malignancy, although further evaluation in the non-hematology setting is needed. In addition, a true point-of-care test, particularly for easily obtained specimens like serum or urine that can be done at the bedside or in the Clinic in a matter of minutes is needed, such as the lateral flow dipstick test, which is under current evaluation. Lastly, improved diagnostic algorithms to diagnose IA in non-neutropenic patients is needed.

Revision and Update of the Consensus Definitions of Invasive Fungal Disease From the European Organization for Research and Treatment of Cancer and the Mycoses Study Group Education and Research Consortium

BACKGROUND

Invasive fungal diseases (IFDs) remain important causes of morbidity and mortality. The consensus definitions of the Infectious Diseases Group of the European Organization for Research and Treatment of Cancer and the Mycoses Study Group have been of immense value to researchers who conduct clinical trials of antifungals, assess diagnostic tests, and undertake epidemiologic studies. However, their utility has not extended beyond patients with cancer or recipients of stem cell or solid organ transplants. With newer diagnostic techniques available, it was clear that an update of these definitions was essential.

METHODS

To achieve this, 10 working groups looked closely at imaging, laboratory diagnosis, and special populations at risk of IFD. A final version of the manuscript was agreed upon after the groups' findings were presented at a scientific symposium and after a 3-month period for public comment. There were several rounds of discussion before a final version of the manuscript was approved.

RESULTS

There is no change in the classifications of "proven," "probable," and "possible" IFD, although the definition of "probable" has been expanded and the scope of the category "possible" has been diminished. The category of proven IFD can apply to any patient, regardless of whether the patient is immunocompromised. The probable and possible categories are proposed for immunocompromised patients only, except for endemic mycoses.

CONCLUSIONS

These updated definitions of IFDs should prove applicable in clinical, diagnostic, and epidemiologic research of a broader range of patients at high-risk.

Performance of the Bronchoalveolar Lavage Fluid Aspergillus Galactomannan Lateral Flow Assay with Cube Reader for Diagnosis of Invasive Pulmonary Aspergillosis: a Multicenter Cohort Study

BACKGROUND

The Aspergillus Galactomannan Lateral Flow Assay (LFA) is a rapid test for the diagnosis of invasive aspergillosis (IA) that has been almost exclusively evaluated in patients with hematologic malignancies. An automated digital cube reader which allows for quantification of results has recently been added to the test kits.

METHODS

We performed a retrospective multicenter study on bronchoalveolar lavage fluid (BALF) samples obtained from 296 patients with various underlying diseases (65% without underlying hematological malignancy) who had BALF galactomannan (GM) ordered between 2013 and 2019 at the University of California San Diego, the Medical University of Graz, Austria, and the Mannheim University Hospital, Germany.

RESULTS

Cases were classified as proven (n=2), probable (n=56), putative (n=30), possible (n=45), and no IA (n=162). The LFA showed an area under the curve (AUC) of 0.865 (95% CI 0.815-0.916) for differentiating proven/probable or putative IA versus no IA, with a sensitivity of 74% and a specificity of 83% at an optical density index cut-off of 1.5. After exclusion of GM as mycological criterion for case classification, diagnostic performance of the LFA was highly similar to GM testing (AUC 0.892 versus 0.893, respectively). LFA performance was consistent across different patient cohorts and centers.

CONCLUSION

In this multicenter study the LFA assay from BALF demonstrated good diagnostic performance for IA that was consistent across patient cohorts and locations. The LFA may serve a role as a rapid test that may replace conventional GM testing in settings where GM results are not rapidly available.

(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.

Pulmonary Aspergillosis: An Evolving Challenge for Diagnosis and Treatment

Aspergillus is a mold that may lead to different clinical pictures, from allergic to invasive disease, depending on the patient’s immune status and structural lung diseases. Chronic pulmonary aspergillosis is an infection with a locally invasive presentation, reported especially in patients with chronic pulmonary disease, while aspergilloma is typically found in patients with previously formed cavities in the lungs. Allergic bronchopulmonary aspergillosis is due to a hypersensitivity reaction to Aspergillus antigens and is more frequently described in patients with moderate-severe asthma or cystic fibrosis. Invasive pulmonary aspergillosis mainly occurs in patients with neutropenia or immunodeficiency, but has increasingly been recognized as an emerging disease of non-neutropenic patients. The significance of this infection has dramatically increased in recent years, considering the high number of patients with an impaired immune state associated with the management and treatment of neoplasm, solid or hematological transplantation, autoimmune diseases, and inflammatory conditions. Moreover, prolonged steroid treatment is recognized as an important risk factor, especially for invasive disease. In this setting, critically ill patients admitted to intensive care units and/or with chronic obstructive pulmonary disease could be at higher risk for invasive infection. This review provides an update on the clinical features and risk factors of pulmonary aspergillosis. Current approaches for the diagnosis, management, and treatment of these different forms of pulmonary aspergillosis are discussed.

Blood Aspergillus PCR: The Good, the Bad, and the Ugly

Invasive Aspergillosis (IA) is one of the most common invasive fungal diseases and is accompanied by high morbidity and mortality. In order to maximize patient outcomes and survival, early and rapid diagnosis has been shown to be pivotal. Hence, diagnostic tools aiding and improving the diagnostic process are ambitiously searched for. In this context, polymerase chain reaction (PCR) may represent a potential candidate. Its additional value and benefits in diagnosis have been demonstrated and are scientifically established. Nevertheless, standardized and widespread usage is sparse because several factors influence diagnostic quality and need to be considered in order to optimize diagnostic performance and outcome. In the following review, the current role of PCR in the diagnosis of IA is explored, with special focus on the strengths and limitations of PCR in different settings.

A clinical approach to respiratory disease in patients with hematological malignancy, with a focus on respiratory infection

Respiratory complications, in particular infections, are common in the setting of hematological malignancy and after hematopoetic stem cell transplant. The symptoms can be nonspecific; therefore, it can be difficult to identify and treat the cause. However, an understanding of the specific immune defect, clinical parameters such as speed of onset, and radiological findings, allows the logical diagnostic and treatment plan to be made. Radiological findings can include consolidation, nodules, and diffuse changes such as ground glass and tree-in-bud changes. Common infections that induce these symptoms include bacterial pneumonia, invasive fungal disease, Pneumocystis jirovecii and respiratory viruses. These infections must be differentiated from inflammatory complications that often require immune suppressive treatment. The diagnosis can be refined with the aid of investigations such as bronchoscopy, computed tomography (CT) guided lung biopsy, culture, and serological tests. This article gives a schema to approach patients with respiratory symptoms in this patient group; however, in the common scenario of a rapidly deteriorating patient, treatment often has to begin empirically, with the aim to de-escalate treatment subsequently after targeted investigations.

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.

Microbiological Laboratory Testing in the Diagnosis of Fungal Infections in Pulmonary and Critical Care Practice. An Official American Thoracic Society Clinical Practice Guideline

Background: Fungal infections are of increasing incidence and importance in immunocompromised and immunocompetent patients. Timely diagnosis relies on appropriate use of laboratory testing in susceptible patients.Methods: The relevant literature related to diagnosis of invasive pulmonary aspergillosis, invasive candidiasis, and the common endemic mycoses was systematically reviewed. Meta-analysis was performed when appropriate. Recommendations were developed using the Grading of Recommendations Assessment, Development, and Evaluation approach.Results: This guideline includes specific recommendations on the use of galactomannan testing in serum and BAL and for the diagnosis of invasive pulmonary aspergillosis, the role of PCR in the diagnosis of invasive pulmonary aspergillosis, the role of β-d-glucan assays in the diagnosis of invasive candidiasis, and the application of serology and antigen testing in the diagnosis of the endemic mycoses.Conclusions: Rapid, accurate diagnosis of fungal infections relies on appropriate application of laboratory testing, including antigen testing, serological testing, and PCR-based assays.

Invasive Aspergillosis in solid-organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated AST-IDCOP guidelines provide information on epidemiology, diagnosis, and management of Aspergillus after organ transplantation. Aspergillus is the most common invasive mold infection in solid-organ transplant (SOT) recipients, and it is the most common invasive fungal infection among lung transplant recipients. Time from transplant to diagnosis of invasive aspergillosis (IA) is variable, but most cases present within the first year post-transplant, with shortest time to onset among liver and heart transplant recipients. The overall 12-week mortality of IA in SOT exceeds 20%; prognosis is worse among those with central nervous system involvement or disseminated disease. Bronchoalveolar lavage galactomannan is preferred for the diagnosis of IA in lung and non-lung transplant recipients, in combination with other diagnostic modalities (eg, chest CT scan, culture). Voriconazole remains the drug of choice to treat IA, with isavuconazole and lipid formulations of amphotericin B regarded as alternative agents. The role of combination antifungals for primary therapy of IA remains controversial. Either universal prophylaxis or preemptive therapy is recommended in lung transplant recipients, whereas targeted prophylaxis is favored in liver and heart transplant recipients. In these guidelines, we also discuss newer antifungals and diagnostic tests, antifungal susceptibility testing, and special patient populations.

Strategies for the management of invasive fungal infections due to filamentous fungi in high-risk hemato-oncological patients

OBJECTIVE

In recent years, the introduction of new antifungals for the prevention of invasive fungal infections (IFIs) in hemato- oncological patients, particularly extended-spectrum azoles, has led to a change in the diagnostic and therapeutic strategies for established or suspected breakthrough IFI. The aim of the study was to identify the diagnostic and therapeutic strategies used in the management of IFIs in hemato-oncological patients in Spain, and to assess compliance with the recommendations of the consensus documents and clinical practice guidelines.

METHODS

An online, anonymous, cross-sectional survey was conducted between January and September 2016 involving 137 specialists from third-level hospitals in Spain with Departments of Hematology that regularly deal with IFIs.

RESULTS

Galactomannan test was available to 95.6% of specialists, and was used in 61.7% of the cases for diagnostic confirmation and early treatment. The (1 → 3) β-D-glucan test was only available to 10.2%. A total of 75.3% of the participants estimated the incidence of breakthrough IFI due to filamentous fungus as being 1-10%. In turn, 83.3% of the participants decided a change in antifungal class after failure of prophylaxis, in concordance with the recommendations of the national and international consensus documents.

CONCLUSIONS

The present study, the first of its kind conducted in Spain, shows that a high percentage of the medical professionals implicated in the management of hemato-oncological patients at high risk of suffering IFIs follow the recommendations of the national and international consensus documents and guidelines.