Seroprevalence of Aspergillus IgG and disease prevalence of chronic pulmonary aspergillosis in a country with intermediate burden of tuberculosis: a prospective observational study

Aspergillus terreus Antibody Serosurveillance in Tyrol: A Population-Based, Cross-Sectional Study of a Healthy Population

The rare, but emerging mold Aspergillus terreus is an important pathogen in some geographical areas, like Tyrol (Austria) and Houston (Texas). The reason for this high prevalence is unknown. The present serosurveillance study aimed to evaluate the trends in levels of A. terreus-specific IgG antibodies in various regions of Tyrol and to compare the results to the environmental spread of A. terreus in Tyrol. Therefore, 1058 serum samples from healthy blood donors were evaluated. Data revealed a significant difference between the Tyrolean Upland and Lowland. Moreover, female participants had higher A. terreus IgG antibody levels than male participants. The differences found in our study are consistent with the distributional differences in environmental and clinical samples described in previous studies, supporting that A. terreus IgG antibody levels reflect the environmental epidemiology of A. terreus in Tyrol.

[Sex in infectious diseases-How sex differences influence the immune response to infections]

The humoral and cellular immune responses to antigen stimulation, vaccinations and infections differ between women and men. Genetic, epigenetic and hormonal factors contribute to the sex-specific immunity. The expression of genes on the X‑chromosome and the effect of sex hormones substantially influence the immune defence against infections. Females show stronger cellular and humoral immune responses to infections than males, but the enhanced immune response often leads to aberrant inflammatory reactions and autoimmune diseases. Men are principally more prone to bacterial, viral and fungal infections and more often show severe disease courses. In contrast, a more reactive female immune system results in significantly more adverse reactions to vaccinations. In order to be able to better identify the multiple sex-specific that have an influence on the immune system, sex-specific differences should be investigated in a differentiated way. The better understanding of the sex-specific differences in the immune response will have a long-term influence on the prevention, diagnostics and treatment of infectious diseases, and will ultimately contribute to improving healthcare of both women and men.

Serum Cytokine Biomarkers for Use in Diagnosing Pulmonary Tuberculosis versus Chronic Pulmonary Aspergillosis

Background

Aspergillus fumigatus-induced chronic pulmonary aspergillosis (CPA), the most common pulmonary tuberculosis (TB) sequela, tends to occur after pulmonary infection with the intracellular pathogen Mycobacterium tuberculosis (Mtb). Timely and accurate detection of A. fumigatus infection of pulmonary TB patients would undoubtedly greatly improve patient prognosis. Currently, the galactomannan (GM) antigen test is commonly used to detect A. fumigatus infection but has poor sensitivity that renders this assay inadequate for use in clinical practice.

Design or Methods

Given the fact CPA and TB induce different host immune responses, we evaluated serum cytokine level profiles of CPA, TB patients and patients with both diseases (CPA-TB) for multiple cytokines and cytokine combinations.

Results

The results revealed significantly higher serum levels of numerous proinflammatory cytokines, including IL-1β, IL-6, IL-8, IL-12p70, IFN-α, IFN-γ and TNF-α, in peripheral blood of CPA-TB patients versus that of TB patients. IL-8 levels alone provided the best discriminatory performance for distinguishing between TB and either CPA-TB patients (AUC = 0.949) or CPA patients (AUC = 0.964). Moreover, both IL-8 and TNF-α (AUC = 0.996) levels could be used to distinguish between TB and CPA-TB patients. Likewise, IL-8, TNF-α and IL-6 levels together could be used to distinguish between CPA-TB and TB patients.

Conclusion

In this study, multiple cytokines were identified that may serve as potential biomarkers for use in detecting TB patients with CPA. Furthermore, our results should enhance understanding of how immune system dysfunctions influence susceptibility to Mtb and/or A. fumigatus infections.

Comparison of Aspergillus-specific antibody cut-offs for the diagnosis of aspergillosis

Background

Aspergillus diseases are frequently encountered in patients who are immunocompromised. Without a prompt diagnosis, the clinical consequences may be lethal. Aspergillus-specific antibodies have been widely used to facilitate the diagnosis of Aspergillus diseases. To date, universally standardized cut-off values have not been established. This study aimed to investigate the cut-off values of Aspergillus-specific antibodies and perform a narrative review to depict the geographic differences in the Taiwanese population.

Methods

We analyzed enrolled 118 healthy controls, 29 patients with invasive aspergillosis (IA), chronic pulmonary aspergillosis (CPA), and allergic bronchopulmonary aspergillosis (ABPA) and 99 with disease control, who were tested for Aspergillus fumigatus and Aspergillus niger-specific IgG and IgE using ImmunoCAP. 99 participants not fulfilling the diagnosis of IA, CPA, and ABPA were enrolled in the disease control group. The duration of retrieval of medical records from June 2018 to September 2021. Optimal cut-offs and association were determined using receiver operating characteristic curve (ROC) analysis.

Results

We found that patients with CPA had the highest A. fumigatus-specific IgG levels while patients with ABPA had the highest A. fumigatus-specific IgE, and A. niger-specific IgG and IgE levels. In patients with CPA and ABPA, the optimal cut-offs of A. fumigatus-specific IgG and A. niger-specific IgG levels were 41.6, 40.8, 38.1, and 69.9 mgA/l, respectively. Geographic differences in the cut-off values of A. fumigatus-specific IgG were also noted. Specifically, the levels were different in eco-climatic zones.

Conclusion

We identified the optimal cut-offs of Aspergillus-specific antibodies to facilitate a precise diagnosis of aspergillosis. The observed geographic differences of the antibody levels suggest that an eco-climatic-specific reference is needed to facilitate a prompt and accurate diagnosis of aspergillosis.

Serological evidence of chronic pulmonary Aspergillosis in tuberculosis patients in Kenya

BACKGROUND

Pulmonary tuberculosis (PTB) is a significant risk factor for fungal infection. The cavitary lesions post PTB serves as a good reservoir for fungal colonization and subsequent infection. Furthermore, the severe immunosuppression associated with HIV and TB co-infection is another predisposition. The inadequate capacity to investigate and manage fungal infection in PTB patients increases their morbidity and mortality. The study aimed to provide serological evidence of chronic pulmonary aspergillosis (CPA) among PTB patients in Kenya. Towards this, we analysed 234 serum samples from patients presenting with persistent clinical features of PTB infections despite TB treatment in four referral hospitals.

METHODS

This was a cross sectional laboratory based study and patients were recruited following an informed consent. Serological detection of Aspergillus fumigatus IgG was done using enzyme-linked immunosorbent assay (Bordier Affinity Products SA). Sputum samples were subjected to microscopy and standard fungal culture. The isolated fungi were subjected to macro and micro morphological identifications and confirmed by sequence analysis of calmadulin, betatubilin and ITS genes.

RESULTS

Serological evidence of CPA or fungal sensitization was 46(19.7%) and equivocal or borderline was 14(6.0%). Mycological investigations of sputum resulted in 88(38%) positive for fungal culture. Aspergillus spp. accounted for 25(28%) of which A. fumigatus was 13(14.8%), A. niger 8(9.1%), A. terreus, A. flavus, A. candidus and A. clavatus 1 (1.1%) each. This was followed by Penicillium spp. 10 (11.4%), Scedosporium spp. 5 (5.7%) and Rhizopus spp. 3 (3.4%). Among the yeasts; Candida albicans accounted for 18(20.5%) followed by C. glabrata 5(5.7%). Cryptococcus spp. was isolated from 3(3.4%) of the samples while 13(14.8%) were other yeasts.

CONCLUSION

Chronic pulmonary aspergillosis is a significant co-morbidity in PTB patients in Kenya that could be misdiagnosed as relapse or treatment failures in the absence of reliable diagnostic and clinical management algorithm. It could be the cause of persistent clinical symptoms despite TB treatment often misdiagnosed as TB smear/GeneXpert MTB/RIF® negative or relapse. We recommend that all patients with persistent clinical symptoms despite TB treatment should be subjected to fungal investigations before retreatment.

Prevalence of chronic pulmonary aspergillosis regarding time of tuberculosis diagnosis in Brazil

BACKGROUND

Data on the prevalence of chronic pulmonary aspergillosis (CPA) in patients with active or cured tuberculosis (TB) are scarce, mainly due to diagnostic difficulties. The diagnosis of CPA is based on pulmonary symptoms and chest computed tomography (CT) scans and is considered confirmed when there is microbiological or serological evidence of Aspergillus spp.

INFECTION

OBJECTIVES

To estimate the prevalence of CPA in patients treated or undergoing treatment for PTB, seen in two referral hospitals in Mato Grosso do Sul, Brazil.

PATIENTS AND METHODS

A total of 193 consecutive patients who were treated or previously treated for pulmonary tuberculosis underwent prospective evaluation: a) clinical evaluation; b) chest CT scan; c) sputum examination-culture for fungi and smears for direct mycology; d) detection of anti-Aspergillus fumigatus antibodies using an enzyme-linked immunosorbent assay Platelia® test; and e) anti-Aspergillus spp. antibodies were assessed via a DID test.

RESULTS

The global prevalence of CPA was 10.9% (95% confidence interval, 7.2-16.1%), but it increased with the time of TB diagnosis. The variables independently associated with CPA were previous pulmonary tuberculosis over 4 years ago and hemoptysis. Cavities, pleural thickening, and the presence of a fungal ball were the most frequent tomographic findings in patients with CPA.

CONCLUSIONS

The high prevalence observed and its increase over time suggest the need for continuous surveillance of CPA in patients with active or previous pulmonary tuberculosis and throughout life, with clinical, tomographic, and serological evaluations (ELISA) for a timely diagnosis and a better prognosis.

Let's talk about Sex Characteristics - as a Risk Factor for Invasive Fungal Diseases

Biological sex, which comprises differences in host sex hormone homeostasis and immune responses, can have a substantial impact on the epidemiology of infectious diseases. Comprehensive data on sex distributions in invasive fungal diseases (IFDs) is lacking. In this review we performed a literature search of in vitro/animal studies, clinical studies, systematic reviews, and meta-analyses of invasive fungal infections. Females represented 51.2% of invasive candidiasis cases, mostly matching the proportions of females among the general population in the United States and Europe (>51%). In contrast, other IFDs were overrepresented in males, including invasive aspergillosis (51% males), mucormycosis (60%), cryptococcosis (74%), coccidioidomycosis (70%), histoplasmosis (61%), and blastomycosis (66%). Behavioral variations, as well as differences related to biological sex, may only in part explain these findings. Further investigations concerning the association between biological sex/gender and the pathogenesis of IFDs is warranted.

Complementary Roles of Short and Long Pentraxins in the Complement-Mediated Immune Response to Aspergillus fumigatus Infections

The ubiquitous mold Aspergillus fumigatus is the major etiologic agent of invasive aspergillosis, a life-threatening infection amongst immune compromised individuals. An increasing body of evidence indicates that effective disposal of A. fumigatus requires the coordinate action of both cellular and humoral components of the innate immune system. Early recognition of the fungal pathogen, in particular, is mediated by a set of diverse soluble pattern recognition molecules (PRMs) that act as "ancestral antibodies" inasmuch as they are endowed with opsonic, pro-phagocytic and killing properties. Pivotal is, in this respect, the contribution of the complement system, which functionally cooperates with cell-borne pattern recognition receptors (PRRs) and other soluble PRMs, including pentraxins. Indeed, complement and pentraxins form an integrated system with crosstalk, synergism, and regulation, which stands as a paradigm of the interplay between PRMs in the mounting and orchestration of antifungal immunity. Following upon our past experience with the long pentraxin PTX3, a well-established immune effector in the host response to A. fumigatus, we recently reported that this fungal pathogen is targeted in vitro and in vivo by the short pentraxin Serum Amyloid P component (SAP) too. Similar to PTX3, SAP promotes phagocytosis and disposal of the fungal pathogen via complement-dependent pathways. However, the two proteins exploit different mechanisms of complement activation and receptor-mediated phagocytosis, which further extends complexity and integration of the complement-pentraxin crosstalk in the immune response to A. fumigatus. Here we revisit this crosstalk in light of the emerging roles of SAP as a novel PRM with antifungal activity.

Chronic Pulmonary Aspergillosis Situation among Post Tuberculosis Patients in Vietnam: An Observational Study

This study provides a brief view of chronic pulmonary aspergillosis (CPA) in the post-tuberculosis treatment community in Vietnam, a high burden tuberculosis (TB) country. In three months in late 2019, 70 post-TB patients managed at Vietnam National Lung Hospital were enrolled. Of these, 38 (54.3%) had CPA. The male/female ratio was 3/1 (28 males and ten females). CPA patients had a mean age of 59 ± 2.3 years (95%CI 54.4-63.6). The mean Body mass index (BMI) was 19.0 ± 0.5 (18.0-20.0) and 16 of 38 (42.1%) patients had concurrent diseases, the most common of which were chronic obstructive pulmonary disease (COPD) and diabetes. Twenty-six patients (68.4%) developed hemoptysis, 21 (55.3%) breathlessness, and weight loss was seen in 30 (78.9%). Anaemia was seen in 15 (39.5%) and 27 of 38 (71.1%) patients had an elevated C-reactive protein (CRP). The most common radiological findings were multiple cavities (52.6%) and pleural thickening (42.7%), followed by aspergilloma (29.0%) and non-specific infiltrates. There were five of 38 patients (13.2%) with a cavity containing a fungal ball on the chest X-ray, but when the high resolution computed tomography (HRCT) was examined, the number of patients with fungal balls rose to 11 (28.9%). Overall, 34 of 38 (89.5%) cases had an elevated Aspergillus IgG with an optical density ≥ 1, and in 2 cases, it was 0.9-1.0 (5%), borderline positive. In nine patients (23.7%) Aspergillus fumigatus was cultured from sputum. CPA is an under-recognised problem in Vietnam and other high burden TB countries, requiring a different diagnostic approach and treatment and careful management. HRCT and Aspergillus IgG serum test are recommended as initial diagnostic tools for CPA diagnosis.

Establishing Aspergillus-Specific IgG Cut-Off Level for Chronic Pulmonary Aspergillosis Diagnosis: Multicenter Prospective Cohort Study

OBJECTIVES

Aspergillus-specific IgG (Asp-IgG) cut-off level in diagnosing chronic pulmonary aspergillosis (CPA) remains unknown.

METHODS

We prospectively recruited participants with clinical suspicion of CPA in three centers in Taiwan during 2019 June to 2020 August. Serum Aspergillus fumigatus-specific IgG (Asp-IgG) (Phadia, Uppsala, UPPS, Sweden) was examined. Optimal cut-off level was determined by Youden's index and validated.

RESULTS

A total of 373 participants were recruited. In the derivation cohort (n = 262), Asp-IgG had an area under the receiver-operating-characteristic curve (AUC) of 0.832. The optimal cut-off level was 40.5 mgA/L. While applying this cut-off level to the validation cohort (n = 111), the sensitivity and specificity were 86.7% and 80.2%. Lowering the cut-off level from 40.5 to 27 mgA/L, the sensitivity was steady (30/36, 83.3% to 31/36, 86.1%) while specificity dropped from 81.9% (276/337) to 63.5% (214/337). Restricting CPA diagnosis to only chronic cavitary pulmonary aspergillosis (CCPA) and chronic fibrosing pulmonary aspergillosis (CFPA) yielded a cut-off level of 42.3 mgA/L in the derivation cohort with a sensitivity of 100% and specificity of 84.4% in the validation cohort.

CONCLUSIONS

Serum Asp-IgG performs well for CPA diagnosis and provides a low false-positive rate when using a higher cut-off level (preferably around 40 mgA/L).

Increased Incidence and Associated Risk Factors of Aspergillosis in Patients with Bronchiectasis

There are insufficient data regarding the relationship between non-cystic fibrosis bronchiectasis and incident aspergillosis. We performed a population-based, matched cohort study using data from the Korean National Health Insurance database between 2003 and 2013. The incidence of aspergillosis was 50/100,000 person-years in the bronchiectasis cohort and 11/100,000 person-years in the matched cohort (subdistribution hazard ratio, 4.53; 95% confidence interval (CI), 3.25–6.32). Among the bronchiectasis cohort, chronic obstructive pulmonary disease (adjusted HR, 1.95; 95% CI, 1.07–3.57), previous pulmonary tuberculosis (adjusted HR, 3.67; 95% CI, 2.03–6.64), and non-tuberculous mycobacterial pulmonary disease (adjusted HR, 11.25; 95% CI, 1.49–85.18) increased the risk of incident aspergillosis. The incidence of aspergillosis in patients with bronchiectasis was approximately 4.5-fold that in those without bronchiectasis. Comorbid pulmonary diseases—chronic obstructive pulmonary disease, previous pulmonary tuberculosis, and non-tuberculous mycobacterial pulmonary disease—significantly increased the risk of aspergillosis in patients with bronchiectasis. Our study indicates that close monitoring is warranted for aspergillosis in patients with bronchiectasis.

Performance of LDBio Aspergillus WB and ICT Antibody Detection in Chronic Pulmonary Aspergillosis

The detection of Aspergillus antibody has a key role in the diagnosis of chronic pulmonary aspergillosis. Western blot (WB) and immunochromatography (ICT) lateral flow detection of Aspergillus antibody can be used as confirmatory and screening assays but their comparative performance in TB patients is not known. This study investigated the performance of these assays among 88 post-tuberculosis patients with suspected CPA. Sensitivity, specificity, receiver operating curve (ROC), area under-curve (AUC) and the agreement between two assays were evaluated. Both WB and ICT showed good sensitivity (80% and 85%, respectively) for detection of Aspergillus antibodies. Substantial agreement (0.716) between these assays was also obtained. The highest AUC result (0.804) was achieved with the combination of WB and ICT. The global intensity of WB correlated with the severity of symptoms in CPA group (p = 0.001). The combination of WB and ICT may increase specificity in CPA diagnosis.

Serology anno 2021-fungal infections: from invasive to chronic

BACKGROUND

Diagnosing invasive or chronic fungal infections is a challenge, particularly in the immunocompromised host. Microscopy and culture remain the reference standard, but are insensitive. The use of non-culture-based techniques is recommended in conjunction with conventional methods to improve the diagnostic yield.

OBJECTIVES

The aim was to provide an updated 2021 inventory of fungal antigen and serology tests for diagnosing invasive and chronic fungal infections, the key focus was set on Aspergillus, Candida and Cryptococcus species.

SOURCES

Pubmed search for publications with the key words fungal antigen tests, laboratory-based diagnosis of invasive pulmonary aspergillosis, chronic pulmonary aspergillosis, invasive candidiasis, invasive fungal infections and cryptococcal infections published from 2017 to 2020.

CONTENT

Antigen assays such as the galactomannan (GM) and β-d-glucan detection systems are frequently used, but these tests vary in sensitivity and specificity, depending on the patient population involved, specimens inspected, cut-offs defined, test strategy applied and inclusion or exclusion of possible fungal case definitions. Multiple different detection systems are available, with recently introduced new point-of-care tests such as the lateral flow device and the lateral flow assay. Despite a wide heterogeneity in populations evaluated, studies indicate a better diagnostic performance of bronchoalveolar lavage GM in comparison with serum GM, and a suboptimal specificity of GM bronchoalveolar lavages (cut-off ≥1) and serum β-d-glucan in non-neutropenic individuals. Point-of-care cryptococcal antigen tests show excellent performance.

IMPLICATIONS

There are fungal antigen detection tests available with excellent to reasonable clinical performance to diagnose invasive fungal infections. Only a few assays are useful to monitor therapeutic response. There are multiple marketed IgG antibody tests to detect Aspergillus fumigatus antibodies, the titres vary widely and the performance differs significantly. In general, diagnostic tests are vulnerable to being affected by the host, the microbe and laboratory setting.

Aspergillus fumigatus and Aspergillus flavus-Specific IgG Cut-Offs for the Diagnosis of Chronic Pulmonary Aspergillosis in Pakistan

Despite a high burden of chronic pulmonary aspergillosis (CPA) in Pakistan, Aspergillus-specific IgG testing is currently not available. Establishing cut-offs for Aspergillus-specific IgG for CPA diagnosis is crucial due to geographical variation. In settings such as Pakistan, where non-Aspergillus fumigatus (mainly A. flavus) Aspergillus species account for the majority of CPA cases, there is a need to explore additional benefit of Aspergillus flavus-specific IgG detection along with A. fumigatus-specific IgG detection. This study was conducted at the Aga Khan University, Karachi, Pakistan after ethical approval. Serum for IgG detection were collected after informed consent from healthy controls (n = 21), diseased controls (patients with lung diseases, n = 18), and CPA patients (n = 21). A. fumigatus and A. flavus IgG were detected using Siemens immulite assay. The sensitivity and specificity of A. fumigatus-specific IgG were 80.95% and 82.05%, respectively at a cut-off of 20 mg/L. The sensitivity and specificity of A. flavus-specific IgG were 80.95% and 79.49% at a cut-off of 30 mg/L. We report, for the first time, performance of A. flavus-specific IgG for CPA diagnosis. Although there was no statistically significant difference between the performance of both antigens, it seems contextually relevant to include A. flavus IgG in the CPA diagnostic algorithm in regions with higher non-A. fumigatus CPA infections.

Diagnostic cut-off value for Aspergillus fumigatus- and flavus-specific IgG with clinical relevance in chronic pulmonary Aspergillus infection: A pilot study in Taiwan

BACKGROUND

The diagnostic cut-off value for chronic pulmonary Aspergillosis (CPA) by Aspergillus fumigatus-specific IgG has never been evaluated In Taiwan. The cut-off value for Aspergillus flavus-specific IgG has not been evaluated worldwide.

OBJECTIVES

Evaluate diagnostic cut-off value of Aspergillus IgG and its application characteristics.

PATIENTS/METHODS

Blood from control groups and treatment-naïve patients with CPA infections was collected for Aspergillus-specific IgG measurements. Controls were patients who had chest radiographic abnormalities and signs of respiratory tract infection, but were negative for Aspergillus and resolved without anti-mould therapy. Confirmation and probability of CPA were defined according to radiological features and positivity for an Aspergillus or galactomannan index. Chest computer tomography patterns were recorded for the presence of aspergilloma or nodules, subacute invasive aspergillosis, chronic cavitary pulmonary aspergillosis and chronic fibrotic pulmonary aspergillosis.

RESULTS

A total of 35 cases and 50 disease controls were included. The levels of A. fumigatus- and A. flavus-specific IgG correlated with CPA progression (P < .05) but not with the presence of Aspergillus species from clinical specimens (P > .05). The best cut-off value for A. fumigatus IgG was 21.7 mg/L with area under curve (AUC) for receiver operating characteristic curve (ROC) 0.934 and had 85.7% sensitivity and 92.0% specificity. For A. flavus IgG, the best cut-off value was 22.1 mgA/L and the AUC was 0.928 with 88.2% sensitivity and 94.1% specificity.

CONCLUSION

The level of Aspergillus-specific IgG correlated with radiographic characteristics in patients with CPA and the best cut-off values compared to controls were 21.7 mgA/L for A. fumigatus-specific IgG and 22.1 mgA/L for A. flavus-specific IgG.