Diagnosing allergic bronchopulmonary aspergillosis in children with cystic fibrosis

Aspergillus in Children and Young People with Cystic Fibrosis: A Narrative Review

Cystic fibrosis is a severe, inherited, life-limiting disorder, and over half of those living with CF are children. Persistent airway infection and inflammation, resulting in progressive lung function decline, is the hallmark of this disorder. Aspergillus colonization and infection is a well-known complication in people with CF and can evolve in a range of Aspergillus disease phenotypes, including Aspergillus bronchitis, fungal sensitization, and allergic bronchopulmonary aspergillosis (ABPA). Management strategies for children with CF are primarily aimed at preventing lung damage and lung function decline caused by bacterial infections. The role of Aspergillus infections is less understood, especially during childhood, and therefore evidence-based diagnostic and treatment guidelines are lacking. This narrative review summarizes our current understanding of the impact of Aspergillus on the airways of children and young people with CF.

Challenging fungal infections in cystic fibrosis: a case of mixed Aspergillus species infection and antifungal combination testing

Aspergillus stands as the predominant fungal genus in the airways of cystic fibrosis (CF) patients, significantly contributing to their morbidity and mortality. Aspergillus fumigatus represents the primary causative species for infections, though the emergence of rare species within the Aspergillus section Fumigati has become noteworthy. Among these, Aspergillus lentulus is particularly significant due to its frequent misidentification and intrinsic resistance to azole antifungal agents. In the management of invasive aspergillosis and resistant infections, combination antifungal therapy has proven to be an effective approach. This report documents a case involving the death of a CF patient due to a pulmonary exacerbation linked to the colonization of multiple Aspergillus species, including A. lentulus, A. fumigatus, and A. terreus, and treated with Itraconazole (ITC) monotherapy. We delineated the procedures used to characterize the Aspergillus isolates in clinical settings and simulated in vitro the impact of the combination antifungal therapy on the isolates obtained from the patient. We evaluated three different combinations: Amphotericin B (AMB)+Voriconazole (VRC), AMB+Anidulafungin (AND), and VRC+AND. Notably, all strains isolated from the patient exhibited a significant decrease in their minimum inhibitory concentration (MIC) or minimum effective concentration (MEC) values when treated with all antifungal combinations. The VRC+AMB combination demonstrated the most synergistic effects. This case report emphasizes the critical importance of susceptibility testing and precise identification of Aspergillus species to enhance patient prognosis. It also underscores the potential benefits of combined antifungal treatment, which, in this case, could have led to a more favourable patient outcome.

Laboratory biomarkers in the diagnosis and follow-up of treatment of allergic bronchopulmonary aspergillosis in cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA), a severe inflammatory respiratory disease, is caused by a hypersensitivity reaction to the colonization of the airways with Aspergillus fumigatus. It is most often described in patients with asthma or cystic fibrosis. The diagnosis of ABPA is based on a combination of clinical, radiological, and immunological findings that have been included in different diagnostic criteria over the years. In this paper, we review the biomarkers included in these diagnostic criteria and novel research biomarkers that may be used in the diagnosis and treatment follow-up of ABPA in cystic fibrosis.

Aspergillus-related lung disease in people with cystic fibrosis: can imaging help us to diagnose disease?

In people with cystic fibrosis (PwCF), viscous sputum and dysfunction of the mucociliary escalator leads to early and chronic infections. The prevalence of Aspergillus fumigatus in sputum is high in PwCF and the contribution of A. fumigatus to the progression of structural lung disease has been reported. However, overall, relatively little is known about the contribution of A. fumigatus to CF lung disease. More knowledge is needed to aid clinical decisions on whether to start antifungal treatment. In this review, we give an overview of A. fumigatus colonisation and infection in PwCF and the different types of pulmonary disease caused by it. Furthermore, we discuss the current evidence for structural lung damage associated with A. fumigatus in PwCF on chest computed tomography and magnetic resonance imaging. We conclude that radiological outcomes to identify disease caused by A. fumigatus can be important for clinical studies and management.

Comparative Analysis of Clinical Parameters and Sputum Biomarkers in Establishing the Relevance of Filamentous Fungi in Cystic Fibrosis

Background

The relationship between fungal culture (FC) positivity and airway inflammation in CF is largely unknown. Identifying the clinical significance of filamentous fungi in CF using both clinical parameters and biomarkers may change our antimicrobial therapeutic strategies.

Objectives

To investigate the clinical characteristics and airway biomarker profile in relation to the detection of filamentous fungi in respiratory samples obtained from CF patients.

Methods

A prospective cohort study over 24 months, including children and adults with CF. Participants provided sputum and/or bronchoalveolar lavage samples, which underwent processing for bacterial and fungal culture, leukocyte differential cell count and biomarker analysis for neutrophil elastase (NE), interleukin-8 (IL-8), galactomannan and tumor necrosis factor receptor type 2 (TNF-R2). We performed FC using neat sputum plugs, an approach shown to be more sensitive compared to routine laboratory testing.

Results

Sixty-one patients provided 76 respiratory samples (72 sputum and 4 BAL). Median age was 17 years (range 6 months-59 years). FC positivity was noted in 49% of the cohort. FC positivity was greater during pulmonary exacerbation compared to the stable state (67 versus 50%). Participants aged 5-30 years had a lower FEV1 within the FC positive group. A significant association between FC positivity and non-tuberculosis mycobacterial (NTM) culture was observed on non-parametric testing (p = 0.022) and regression analysis (p = 0.007). Exposure to indoor mold was a predictor for FC positivity (p = 0.047). There was a trend towards increased lung clearance index (LCI), bronchiectasis and intravenous antibiotic use in the FC positive group. There was no significant difference in biomarkers between FC positive and negative patients.

Conclusion

Aspergillus. fumigatus is the commonest filamentous fungi cultured from CF airways. We found no difference in the airway biomarker profile between FC positive and negative patients. The role of galactomannan and TNFR2 as fungal specific biomarkers in CF remains uncertain. FC positivity is associated with a lower FEV₁ in younger patients, a lower LCI, NTM positivity, bronchiectasis, and intravenous antibiotic exposure. Larger trials are needed to determine the role of galactomannan and TNF-R2 as potential fungal biomarkers in CF.

Current Approach in the Diagnosis and Management of Allergic Bronchopulmonary Aspergillosis in Children With Cystic Fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a complex pulmonary disorder characterized by a hypersensitivity reaction to Aspergillus fumigatus, and almost always seen in patients with cystic fibrosis (CF) and asthma. Fungal hyphae leads to an ongoing inflammation in the airways that may result in bronchiectasis, fibrosis, and eventually loss of lung function. Despite the fact that ABPA is thought to be more prevalent in CF than in asthma, the literature on ABPA in CF is more limited. The diagnosis is challenging and may be delayed because it is made based on a combination of clinical features, and radiologic and immunologic findings. With clinical deterioration of a patient with CF, ABPA is important to be kept in mind because clinical manifestations mimic pulmonary exacerbations of CF. Early diagnosis and appropriate treatment are important in preventing complications related to ABPA. Treatment modalities involve the use of anti-inflammatory agents to suppress the immune hyperreactivity and the use of antifungal agents to reduce fungal burden. Recently, in an effort to treat refractory patients or to reduce adverse effects of steroids, other treatment options such as monoclonal antibodies have started to be used. Intensive research of these new agents in the treatment of children is being conducted to address insufficient data.

Asthma and Fungus: Role in Allergic Bronchopulmonary Aspergillosis (ABPA) and Other Conditions

Asthma is an allergic, respiratory disorder characterized by hyper responsiveness of the airway to external stimuli. Considerable research is currently being directed towards understanding the role of environmental and genetic factors contributing to the development of asthma and its severity. Recent years have seen a substantial rise in evidence linking fungi to asthma. Few major clinical conditions associated with fungal sensitization and hypersensitive immune response are Allergic bronchopulmonary aspergillosis (ABPA), Allergic fungal rhinosinusitis (AFRS) and Severe asthma with fungal sensitization (SAFS). The most common fungi implicated in these conditions belong to genus Aspergillus, although an association with several other fungi has been described. In this review authors discuss the varying clinical characteristics of fungus induced respiratory complications in individuals with asthma. They also highlight the epidemiology of these conditions including their prevalence in children and their fungal etiological profile. Laboratory diagnostic methods and clinical case definitions have also been discussed. Future studies evaluating the role of fungal exposure and susceptibility to asthma are required. Till date there are no guidelines for the diagnosis and treatment of ABPA in pediatric population, thus it is also imperative to establish validated clinical definitions of fungal allergic manifestations in pediatric patients with asthma to fully understand this complex interaction.

Clinical indications and scanning protocols for chest CT in children with cystic fibrosis: a survey of UK tertiary centres

OBJECTIVES

Chest CT is increasingly used to monitor disease progression in children with cystic fibrosis (CF) but there is no national guideline regarding its use. Our objective was to assess the indications for undertaking chest CT and the protocols used to obtain scans.

DESIGN SETTING AND PARTICIPANTS

An electronic questionnaire was developed to assess clinicians views on chest CT in children with CF. It included general questions on perceived benefits and specific questions about its role in five clinical scenarios. It was sent to the clinical lead in 27 UK paediatric CF centres. A separate questionnaire was developed to collect the technical details of chest CT in children with CF. It was sent to the superintendent radiographer at each of the 27 centres.

RESULTS

Responses were obtained from 27 (100%) clinical leads and 22 (81%) superintendent radiographers. 93% clinicians reported chest CT useful in monitoring disease progression and 70% said it frequently altered management. Only 5 (19%) undertook routine scans. To aid diagnosis, 81% performed chest CT in non-tuberculous mycobacterial disease and 15% in allergic bronchopulmonary aspergillosis. There was wide variation in the perceived need for and/or timing of chest CT in children with reduced lung function with no benefit from intravenous antibiotics, new cystic changes on chest X-ray, and lobar collapse. The radiographers reported using a mixture of helical (volumetric) and axial scans depending on the clinical question, the age and the cooperation of the child. When indicated, 6 (27%) used sedation and 16 (73%) general anaesthetic. Only 1 (5%) used intravenous contrast routinely and 3 (14%) obtained expiratory images routinely.

CONCLUSIONS

There is marked variation in the use of chest CT in children with CF and in the scan protocols. The lack of a national guideline is likely to be contributing to this lack of standardisation.

Aspergillus infections in cystic fibrosis

Patients with cystic fibrosis (CF) suffer from chronic lung infection and airway inflammation. Respiratory failure secondary to chronic or recurrent infection remains the commonest cause of death and accounts for over 90% of mortality. Bacteria as Staphylococcus aureus, Pseudomonas aeruginosa and Burkholderia cepacia complex have been regarded the main CF pathogens and their role in progressive lung decline has been studied extensively. Little attention has been paid to the role of Aspergillus spp. and other filamentous fungi in the pathogenesis of non-ABPA (allergic bronchopulmonary aspergillosis) respiratory disease in CF, despite their frequent recovery in respiratory samples. It has become more apparent however, that Aspergillus spp. may play an important role in chronic lung disease in CF. Research delineating the underlying mechanisms of Aspergillus persistence and infection in the CF lung and its link to lung deterioration is lacking. This review summarizes the Aspergillus disease phenotypes observed in CF, discusses the role of CFTR (cystic fibrosis transmembrane conductance regulator)-protein in innate immune responses and new treatment modalities.

Chronic Aspergillus fumigatus colonization of the pediatric cystic fibrosis airway is common and may be associated with a more rapid decline in lung function

Filamentous fungi are commonly isolated from the respiratory tract of CF patients, but their clinical significance is uncertain and the reported incidence variable. We report on the degree of Aspergillus fumigatus airway colonization in a tertiary pediatric CF cohort, evaluate the sensitivity of routine clinical sampling at detecting A. fumigatus, and compare lung function of A. fumigatus-colonized and non-colonized children.We carried out an 8-year retrospective cohort analysis using local databases, examining 1024 respiratory microbiological specimens from 45 children. Nineteen (42%) had a positive A. fumigatus culture at least once during the 8-year period, with 10 (22%) children persistently colonized. Overall, 29% of 48 bronchoalveolar lavage (BAL) samples tested positive for A. fumigatus, compared with 14% of 976 sputum samples. Of 33 children for whom lung function data were available during the study period, seven were classed as having severe lung disease, of whom four (57%) were persistently colonized with A. fumigatus.We conclude that chronic A. fumigatus colonization of the CF airway is common, and may be associated with worse lung function. In our practice, BAL appears superior at detecting lower airway A. fumigatus compared to sputum samples.

Aspergillus sensitization or carriage in cystic fibrosis patients

BACKGROUND

Aspergillus fumigatus (Af) sensitization and persistent carriage are deleterious to lung function, but no consensus has been reached defining these medical entities. This work aimed to identify possible predictive factors for patients who become sensitized to Af, compared with a control group of non-sensitized Af carriers.

METHODS

Between 1995 and 2007, 117 pediatric patients were evaluated. Demographic data, CFTR gene mutations, body mass index and FEV1 were recorded. The presence of Af in sputum, the levels of Af-precipitin, total IgE (t-IgE) and specific IgE to Af (Af-IgE) were determined. Patients were divided into 2 groups: (1) "sensitization": level of Af-IgE > 0.35 IU/mL with t-IgE level < 500 IU/mL and (2) "persistent or transient carriage": Af-IgE level ≤ 0.35 IU/mL with either an Af transient or persistent positive culture. A survival analysis was performed with the appearance of Af-IgE in serum as an outcome variable.

RESULTS

Severe mutation (hazard ratio = 3.2), FEV1 baseline over 70% of theoretical value (hazard ratio = 4.9), absence of Pa colonization, catalase activity and previous azithromycin administration (hazard ratio = 9.8, 4.1 and 1.9, respectively) were predictive factors for sensitization. We propose a timeline of the biological events and a tree diagram for risk calculation.

CONCLUSIONS

Two profiles of cystic fibrosis patients can be envisaged: (1) patients with nonsevere mutation but low FEV1 baselines are becoming colonized with Af or (2) patients with high FEV1 baselines who present with severe mutation are more susceptible to the Af sensitization and then to the presentation of an allergic bronchopulmonary aspergillosis event.

Fungi: the neglected allergenic sources

Allergic diseases are considered the epidemics of the twentieth century estimated to affect more than 30% of the population in industrialized countries with a still increasing incidence. During the past two decades, the application of molecular biology allowed cloning, production and characterization of hundreds of recombinant allergens. In turn, knowledge about molecular, chemical and biologically relevant allergens contributed to increase our understanding of the mechanisms underlying IgE-mediated type I hypersensitivity reactions. It has been largely demonstrated that fungi are potent sources of allergenic molecules covering a vast variety of molecular structures including enzymes, toxins, cell wall components and phylogenetically highly conserved cross-reactive proteins. Despite the large knowledge accumulated and the compelling evidence for an involvement of fungal allergens in the pathophysiology of allergic diseases, fungi as a prominent source of allergens are still largely neglected in basic research as well as in clinical practice. This review aims to highlight the impact of fungal allergens with focus on asthma and atopic dermatitis.

HLA-DRB1 and HLA-DQB1 genes on susceptibility to and protection from allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity pulmonary disease that affects both patients with cystic fibrosis (CF) and those with asthma. HLA-DRB1 alleles have previously been associated with ABPA-CF susceptibility; however, HLA-DQB1 allele associations have not been clearly established. The aim of the present study was to investigate HLA class II associations in patients with ABPA-CF and determine their roles in susceptibility or protection. Patients with ABPA-CF, patients with CF without ABPA, patients with asthma without ABPA (AST), and healthy controls were included in this study. DNA was extracted by automatic extractor. HLA-DRB1 and -DQB1 genotyping was performed by the Luminex PCR-SSOP method (One Lambda, Canoga Park, CA, USA). Allele specific PCR-SSP was also performed by high-resolution analysis (One Lambda). Statistical analysis was performed with SSPS and Arlequin software. Both HLA-DRB1*5:01 and -DRB1*11:04 alleles occurred with greater frequency in patients with ABPA-CF than in those with AST and CF and control subjects, corroborating previously published data. On the other hand, analysis of haplotypes revealed that almost all patients with ABPA-CF lacking DRB1*15:01 or DRB1*11:04 carry either DRB1*04, DRB1*11:01, or DRB1*07:01 alleles. In the HLA-DQB1 region, the HLA-DQB1*06:02 allele occurred more frequently in patients with ABPA-CF than in those with AST and CF and healthy controls, whereas HLA-DQB1*02:01 occurred less frequently in patients with ABPA-CF. These data confirm that there is a correlation between HLA-DRB1*15:01, -DRB1*11:04, DRB1*11:01, -DRB1*04 and -DRB1*07:01 alleles and ABPA-CF susceptibility and suggest that HLA-DQB1*02:01 is an ABPA-CF resistance allele.

Assessment of Aspergillus sensitization or persistent carriage as a factor in lung function impairment in cystic fibrosis patients

BACKGROUND

Cystic fibrosis (CF) patients presenting with persistent carriage of, or sensitization to, Aspergillus fumigatus are often treated with antifungal therapies because the presence of the fungus is commonly thought to impede lung function, even in the absence of allergic bronchopulmonary aspergillosis (ABPA). The aim of this study was to assess Aspergillus-related status modulating the forced expiratory volume in 1 s (FEV₁) of CF patients.

METHODS

From 1995 to 2007, 251 patients were evaluated. Demographic data, cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations, body mass index, and FEV(1) were recorded. The presence of A. fumigatus and Pseudomonas aeruginosa in sputum and the levels of A. fumigatus precipitin, total IgE (t-IgE), and specific anti-A. fumigatus IgE (Af-IgE) were determined. Patients were divided into 3 groups: (1) ABPA: A. fumigatus precipitin ≥3 lines, Af-IgE > 0.35 IU/ml, and t-IgE ≥500 IU/ml; (2) sensitization: Af-IgE > 0.35 IU/ml but t-IgE < 500 IU/ml; and (3) persistent carriage: Af-IgE ≤ 0.35 IU/ml with either an A. fumigatus persistent positive culture or an A. fumigatus precipitin ≥3 lines, provided this serological finding had been found associated with at least 1 A. fumigatus-positive culture. The remaining patients represented the control group. A multivariate analysis was carried out with FEV(1) as the outcome variable.

RESULTS

ABPA, sensitization, and persistent carriage were significantly associated with a larger decline in FEV₁ compared with the control group, with odds ratios of 15.9, 14.9, and 10.7, respectively. This association was independent of other associated factors (P. aeruginosa transient detection, age, being underweight, and low FEV₁ at baseline).

CONCLUSIONS

In addition to ABPA, sensitization and persistent carriage appear to have an impact on pulmonary function in CF patients.

Serum markers for allergic bronchopulmonary aspergillosis in cystic fibrosis: State of the art and further challenges

Allergic bronchopulmonary aspergillosis (ABPA), which results from hypersensitivity, primarily to Aspergillus, represents a severe complication in patients suffering from asthma or cystic fibrosis (CF). Since early treatment of ABPA is supposed to prevent long-term damages, ABPA has to be diagnosed promptly. However, this diagnosis is not straightforward due to clinical and radiological features of ABPA overlapping with those of CF. Despite ABPA specific diagnosis criteria proposed by the Cystic Fibrosis Foundation in 2003, making a definitive ABPA diagnosis in CF patients remains a challenge. Recent advances in the immunopathogenesis of ABPA have initiated the development of new serological tests, such as the recently reported detection of specific IgE to recombinant A. fumigatus allergens, or Thymus- and activation-regulated chemokine (TARC / CCL17), both of which are of value in the diagnosis of APBA. We review in this paper the serum markers that can advance ABPA diagnosis in CF patients, ranging from the well known criteria (anti-A. fumigatus IgE, IgG, and precipitins) to the recent biomarkers (IgE towards recombinant A. fumigatus allergens or TARC detection). Taking into account the up-dated physiopathology of ABPA, we discuss their place and their usefulness, especially TARC, to improve early ABPA detection and monitoring in CF patients.

Pulmonary infections

This paper reviews the most common imaging findings of pulmonary infection in children. Pneumonia is a leading cause of mortality in children in developing and industrialized countries. While the imaging findings usually are nonspecific, correlation with the patient's age, immune status and pertinent history can limit the differential diagnoses. The paper will review the common and unique features of pneumonia caused by specific organisms and in specific patient populations.

Characteristics of pathogenic fungi and antifungal therapy in cystic fibrosis

A defective mucociliary clearance facilitates colonization with bacteria and fungal spores in cystic fibrosis patients. Yeasts and molds are cultured from the cystic fibrosis respiratory tract and often their clinical relevance is unknown. Candida spp. are the most commonly isolated yeasts, whereas Aspergillus spp., Scedosporium apiospermum, as well as Exophiala dermatitidis in some countries, are the most frequent molds recovered from respiratory specimens. Molecular biotyping studies have revealed that some fungal genotypes are capable of chronically colonizing the airways. Persistent Aspergillus fumigatus infection is associated with an increased risk of pulmonary exacerbations requiring hospitalization. The prevalence of non-Aspergillus molds may be underestimated due to overgrowth of Pseudomonas and Aspergillus spp. on routine media. Allergic bronchopulmonary aspergillosis is usually treated by oral steroids and an antifungal azole drug. Interactions with the co-medication have to be considered. A small number of antifungal pharmacokinetic studies indicate a high inter-subject variability for itraconazole, voriconazole and posaconazole, and therefore therapeutic drug monitoring is recommended.

Severe asthma with fungal sensitization in a child: response to itraconazole therapy

People with severe asthma with fungal sensitization may represent an underdiagnosed subset of patients with refractory disease. It is important to know that such patients may benefit from adjunct treatment with antifungal agents. We describe here the case of a child with refractory asthma, persistent airway obstruction, a serum immunoglobulin E level of >20000 IU/mL, and severe eosinophilic airway infiltration. Although he did not meet diagnostic criteria for allergic bronchopulmonary aspergillosis, he demonstrated evidence of sensitization to several fungi and responded dramatically to the addition of itraconazole therapy. We also discuss emerging hypotheses regarding fungal-induced asthma.