LDBio Aspergillus immunochromatographic test lateral flow assay for IgG/IgM antibody detection in chronic pulmonary aspergillosis: Single-centre evaluation and meta-analysis

Epidemiology of the relationship between allergic bronchopulmonary aspergillosis and asthma

PURPOSE OF REVIEW

Allergic bronchopulmonary aspergillosis (ABPA) can complicate the natural history of asthmatic patients, especially the more severe ones, worsening disease control and increasing the need for therapies, steroids in particular, and medical care. The aim of the present review is to summarize the latest epidemiological data related to the relationship between asthma and ABPA and to offer a summary of the most recent strategies that could potentially facilitate in the identification of ABPA in asthmatic patients.

RECENT FINDINGS

In the last years, great efforts have been made by researchers worldwide to provide reliable epidemiological data on fungal sensitization and ABPA, especially in severe asthma patients both in adult and pediatric population. Data differ depending on the geographical area and population studied, but pooled data show a concerning 11% of severe asthma patients having ABPA and one out of four asthmatic patients being sensitized to fungi, Aspergillus fumigatus in particular.

SUMMARY

Reliable epidemiological data and advances in the diagnostic procedures can facilitate the detection of ABPA among asthmatic patients, improving the management of a still under-recognized and challenging condition.

Sensitivity and specificity of LDBio Aspergillus ICT lateral flow assay for diagnosing allergic bronchopulmonary aspergillosis in adult asthmatics

BACKGROUND

Aspergillus fumigatus-specific IgG estimation is crucial for diagnosing allergic bronchopulmonary aspergillosis (ABPA). A point-of-care LDBio immunochromatographic lateral flow assay (LFA) had 0%-90% sensitivity to detect IgG/IgM antibodies against A. fumigatus.

OBJECTIVE

To assess the accuracy of LDBio-LFA in diagnosing ABPA, using the modified ISHAM-ABPA working group criteria as the reference standard. The secondary objective was to compare the diagnostic performance between LDBio-LFA and A. fumigatus-specific IgG (cut-offs, 27 and 40 mgA/L), using a multidisciplinary team (blinded to A. fumigatus-IgG and LDBio-LFA results) diagnosis of ABPA as the reference standard.

METHODS

We prospectively enrolled adult subjects with asthma and ABPA. We performed the LDBio-LFA per the manufacturer's recommendations. We used the commercially available automated fluorescent enzyme immunoassay for measuring serum A. fumigatus-specific IgG. We used the same serum sample to perform both index tests. The tests were performed by technicians blinded to the results of other tests and clinical diagnoses.

RESULTS

We included 123 asthmatic and 166 ABPA subjects, with a mean ± SD age of 37.4 ± 14.4 years. Bronchiectasis and high-attenuation mucus were seen in 93.6% (146/156) and 24.3% (38/156) of the ABPA subjects. The sensitivity and specificity of LDBio-LFA in diagnosing ABPA were 84.9% and 82.9%, respectively. The sensitivity of serum A. fumigatus-specific IgG ≥27 mgA/L was 13% better than LDBio-LFA, with no difference in specificity. There was no significant difference in sensitivity and specificity between LDBio-LFA and serum A. fumigatus-IgG ≥40 mgA/L.

CONCLUSION

LDBio-LFA is a valuable test for diagnosing ABPA. However, a negative test should be confirmed using an enzyme immunoassay.

Chronic Pulmonary Aspergillosis: Clinical Presentation and Management

Chronic pulmonary aspergillosis (CPA) refers to a number of clinical syndromes resulting from the presence and local proliferation of Aspergillus organisms in the lungs of patients with chronic lung disease. CPA is more common than was realized two decades ago. Recognition remains poor, despite recent studies from many countries highlighting the high prevalence in at-risk populations. In low- and middle-income countries, CPA may be misdiagnosed and treated as tuberculosis (TB). In addition, CPA may develop following successful TB treatment. The coronavirus disease pandemic has resulted in significant disruption to provision of TB care, likely leading to more extensive lung damage, which could increase the risk for CPA.Although CPA refers to various syndromes, the classic presentation is that of chronic cavitary pulmonary aspergillosis, which manifests as one or more progressive cavities with or without a fungal ball, accompanied by systemic and respiratory symptoms for at least 3 months. Diagnosis relies on Aspergillus immunoglobulin G in serum, as sputum culture lacks sensitivity. Differential diagnosis includes mycobacterial infection, bacterial lung abscess or necrotizing pneumonia, lung cancer, and endemic fungi.The aim of antifungal treatment in CPA is to improve symptoms and quality of life, and to halt progression, and possibly reverse radiological changes. Current recommendations suggest treatment for 6 months, although in practice many patients remain on long-term treatment. Improvement may manifest as weight gain and improvement of symptoms such as productive cough, hemoptysis, and fatigue. Surgical management should be considered in cases of diagnostic uncertainty, in significant hemoptysis, and when there is concern for lack of response to therapy. Itraconazole and voriconazole are the first-line azoles, with more experience now accumulating with posaconazole and isavuconazole. Side effects are frequent and careful monitoring including therapeutic drug monitoring is essential. Intravenous antifungals such as echinocandins and amphotericin B are used in cases of azole intolerance or resistance, which often develop on treatment. Relapse is seen after completion of antifungal therapy in around 20% of cases, mostly in bilateral, high-burden disease.Several research priorities have been identified, including characterization of immune defects and genetic variants linked to CPA, pathogenetic mechanisms of Aspergillus adaptation in the lung environment, the contribution of non-fumigatus Aspergillus species, and the role of new antifungal agents, immunotherapy, and combination therapy.

Chronic pulmonary aspergillosis: comprehensive insights into epidemiology, treatment, and unresolved challenges

Chronic pulmonary aspergillosis (CPA) is a challenging respiratory infection caused by the environmental fungus Aspergillus. CPA has a poor prognosis, with reported 1-year mortality rates ranging from 7% to 32% and 5-year mortality rates ranging from 38% to 52%. A comprehensive understanding of the pathogen, pathophysiology, risk factors, diagnosis, surgery, hemoptysis treatment, pharmacological therapy, and prognosis is essential to manage CPA effectively. In particular, Aspergillus drug resistance and cryptic species pose significant challenges. CPA lacks tissue invasion and has specific features such as aspergilloma. The most critical risk factor for the development of CPA is pulmonary cavitation. Diagnostic approaches vary by CPA subtype, with computed tomography (CT) imaging and Aspergillus IgG antibodies being key. Treatment strategies include surgery, hemoptysis management, and antifungal therapy. Surgery is the curative option. However, reported postoperative mortality rates range from 0% to 5% and complications range from 11% to 63%. Simple aspergilloma generally has a low postoperative mortality rate, making surgery the first choice. Hemoptysis, observed in 50% of CPA patients, is a significant symptom and can be life-threatening. Bronchial artery embolization achieves hemostasis in 64% to 100% of cases, but 50% experience recurrent hemoptysis. The efficacy of antifungal therapy for CPA varies, with itraconazole reported to be 43-76%, voriconazole 32-80%, posaconazole 44-61%, isavuconazole 82.7%, echinocandins 42-77%, and liposomal amphotericin B 52-73%. Combinatorial treatments such as bronchoscopic triazole administration, inhalation, or direct injection of amphotericin B at the site of infection also show efficacy. A treatment duration of more than 6 months is recommended, with better efficacy reported for periods of more than 1 year. In anticipation of improvements in CPA management, ongoing advances in basic and clinical research are expected to contribute to the future of CPA management.

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.

Developments in Fungal Serology

Purpose of Review

The true incidence of fungal disease is hampered by conventionally poor diagnostic tests, limited access to advanced diagnostics, and limited surveillance. The availability of serological testing has been available for over two decades and generally underpins the modern diagnosis of the most common forms of fungal disease. This review will focus on technical developments of serological tests for the diagnosis of fungal disease, describing advances in clinical performance when available.

Recent Findings

Despite their longevity, technical, clinical, and performance limitations remain, and tests specific for fungal pathogens outside the main pathogens are lacking. The availability of LFA and automated systems, capable of running multiple different tests, represents significant developments, but clinical performance data is variable and limited.

Summary

Fungal serology has significantly advanced the diagnosis of the main fungal infections, with LFA availability increasing accessibility to testing. Combination testing has the potential to overcome performance limitations.

Importance of Aspergillus-Specific Antibody Screening for Diagnosis of Chronic Pulmonary Aspergillosis after Tuberculosis Treatment: A Prospective Follow-Up Study in Ghana

Chronic pulmonary aspergillosis (CPA) often occurs in patients that have been previously treated for pulmonary tuberculosis (PTB). A limited number of studies have looked at the development of CPA at different times following the completion of a PTB treatment course. This prospective longitudinal study aimed to determine the incidence of CPA at two timepoints, at the end of the PTB treatment (T₁) and six months post-treatment (T₂). Patients with confirmed PTB from a previous study who were placed on anti-TB medication were followed up and screened for CPA at T₁ and T₂ by assessing their symptoms, evaluating their quality of life, and screening them for Aspergillus infection by performing antibody testing and cultures. CPA was defined by the Global Action for Fungal Infections (GAFFI) diagnostic algorithm. Forty-one patients were enrolled, of whom thirty-three patients (80%) and twenty-eight patients (68%) were resurveyed at T₁ and T_2, respectively. The rate of new CPA was 3.3% (1/33) and 7.4% (2/27) at T₁ and T₂, respectively, with an overall incidence of 10.7% (3/28) among the patients at both T₁ and T₂. A positive Aspergillus-specific antibody test was an indicator for CPA in all three patients. Aspergillus-specific antibody screening during and after the end of an anti-TB treatment regimen may be important for early detection of CPA in high-PTB-burden settings.

Chronic Pulmonary Aspergillosis is Common among Patients with Presumed Tuberculosis Relapse in Ghana

Chronic pulmonary aspergillosis (CPA) may mimic pulmonary tuberculosis (PTB). The two diseases are clinically indistinguishable and may result in CPA misdiagnosed as PTB or vice versa. Although PTB is largely recognised as a differential diagnosis of CPA and often ruled out prior to CPA diagnosis, the reverse is uncommon. The aim of this study was to determine the proportion of CPA cases among patients being assessed for PTB. A cross-sectional survey was conducted among consecutive patients referred for GeneXpert Mycobacterium tuberculosis test for the diagnosis of PTB at the Korle-Bu Teaching Hospital, Accra, Ghana. Patients’ demographics, clinical and socioeconomic details were obtained using a structured questionnaire. Blood was collected for Aspergillus and HIV serology, and sputum samples obtained for Aspergillus culture. Chest radiograph was obtained, and computed tomography scan was also done for patients with positive Aspergillus serology or cavitation. CPA was defined using an algorithm developed by the Global Action for Fungal Infections (GAFFI) international expert panel. A total of 154 patients were included in the analysis, of whom 134 (87%) did not have a prior PTB diagnosis. There were 41 (26.6%) GeneXpert positive cases. CPA prevalence was 9.7% overall, but 50% in patients with a prior history of PTB and 3.7% in those without previous PTB. Although CPA is rarely considered as a differential diagnosis of PTB in Ghana, our findings show that CPA may affect half of patients being assessed for PTB relapse. Efforts to diagnose CPA should be prioritised in this patient group.