Intravenous antibiotics reduce the presence ofAspergillusin adult cystic fibrosis sputum

Inhaled corticosteroids and Aspergillus fumigatus isolation in cystic fibrosis

Aspergillus fumigatus isolation in cultures from respiratory specimens of patients with cystic fibrosis (CF) is quite common; however, the role of A. fumigatus as a pathogen and whether its presence is associated with progression of pulmonary disease remain unclear. We investigated the association between inhaled corticosteroids and the recovery of A. fumigatus by performing a retrospective cohort study of CF patients born between 1988 and 1996. The patients' medical records from their first visit to the CF Center until December 2010 were reviewed. Outcomes were the occurrence of A. fumigatus first isolation, chronic colonization, or the last visit at the CF Center. A number of possible confounders were included in the multivariate logistic regression analysis in order to identify an independent association between inhaled corticosteroids and colonization status. A total of 121 patients were included in the study. Thirty-nine patients (32.2%) had at least one positive culture and 14 (11.6%) developed chronic colonization. Multivariate logistic regression analysis was used to determine the independent effect of inhaled corticosteroids on the odds of first isolation (odds ratio [OR], 1.165; 95% confidence interval [CI], 1.015-1.337; P = 0.029) and chronic colonization (OR, 1.180; 95% CI, 1.029-1.353; P = 0.018). In conclusion, A. fumigatus first isolation and chronic colonization are associated with the duration of inhaled corticosteroid treatment.

Fungal infections and treatment in cystic fibrosis

PURPOSE OF REVIEW

This review summarizes some of the important recent findings concerning fungal airway infections in patients with cystic fibrosis (CF). For many years, both researchers and clinicians have focused on the problems in CF caused by chronic bacterial airway infection with organisms such as Haemophilus, Staphylococcus and Pseudomonas. However, until recently, the lack of sensitive culture techniques to isolate fungi in sputum, bronchoalveolar lavage fluid and other respiratory tract samples has limited the recognition of fungal species and their possible role in CF airway infections.

RECENT FINDINGS

Recent studies using fungal-selective culture media and molecular techniques have shown a plethora of different fungal species in the sputum expectorated from CF patients. Cross-sectional studies have shown associations between Aspergillus and Candida in the sputum and worse lung function. The presence of allergic bronchopulmonary aspergillosis is likely to be a negative prognostic factor, but whether simple fungal colonization itself indicates future problems is not clear. Current research is now examining these epidemiological associations to try to determine the clinical implications. This will help determine whether fungal colonization/infection is associated with worse outcome in CF patients.

SUMMARY

At present, there is no conclusive evidence that fungal organisms cause respiratory decline. Recent studies of antifungal therapy in CF patients have reported differing results, so further investigations in this area are needed.

What is the importance of classifying Aspergillus disease in cystic fibrosis patients?

Aspergillus species are commonly isolated from lower respiratory tract samples of patients with cystic fibrosis (CF) and markers of immunological sensation to Aspergillus are frequently encountered in this group of patients; however, the contribution of Aspergillus to CF lung disease outside of the typical complications of ABPA and aspergilloma formation remains largely unclear. Patients with CF show discretely different responses to Aspergillus, though the underlying reasons for this variation are unknown. Recent work has begun to allow us to categorize patient responses to Aspergillus based upon molecular markers of infection and immune sensitization. Aspergillus sensitization and/or airway infection is associated with worse FEV1, in CF and other patients (asthma, chronic obstructive pulmonary disease, bronchiectasis). Classification of different clinical phenotypes of Aspergillus will enable future studies to determine the natural history of different manifestations of Aspergillus disease and evaluate the effects of intervention with antifungal therapy.

Induction of gliotoxin secretion in Aspergillus fumigatus by bacteria-associated molecules

Aspergillus fumigatus is the most common causative agent of mold diseases in humans, giving rise to life-threatening infections in immunocompromised individuals. One of its secreted metabolites is gliotoxin, a toxic antimicrobial agent. The aim of this study was to determine whether the presence of pathogen-associated molecular patterns in broth cultures of A. fumigatus could induce gliotoxin production. Gliotoxin levels were analyzed by ultra-performance liquid chromatography and mass spectrometry. The presence of a bacteria-derived lipopolysaccharide, peptidoglycan, or lipoteichoic acid in the growth media at a concentration of 5 μg/ml increased the gliotoxin concentration in the media by 37%, 65%, and 35%, respectively. The findings reveal a correlation between the concentrations of pathogen-associated molecular patterns and gliotoxin secretion. This shows that there is a yet uncharacterized detection system for such compounds within fungi. Inducing secondary metabolite production by such means in fungi is potentially relevant for drug discovery research. Our results also give a possible explanation for the increased virulence of A. fumigatus during bacterial co-infection, one that is important for the transition from colonization to invasiveness in this pulmonary disease.

Fungi in the cystic fibrosis lung: bystanders or pathogens?

Improvement to the life expectancy of people with cystic fibrosis (PWCF) brings about novel challenges including the need for evaluation of the role of fungi in the cystic fibrosis (CF) lung. To determine if such organisms represent bystanders or pathogens affecting clinical outcomes we review the existing knowledge from a clinical, biochemical, inflammatory and immunological perspective. The prevalence and importance of fungi in the CF airway has likely been underestimated with the most frequently isolated filamentous fungi being Aspergillus fumigatus and Scedosporium apiospermum and the major yeast Candida albicans. Developing non-culture based microbiological methods for fungal detection has improved both our classification and understanding of their clinical consequences including localized, allergic and systemic infections. Cross-kingdom interaction between bacteria and fungi are discussed as is the role of biofilms further affecting clinical outcome. A combination of host and pathogen-derived factors determines if a particular fungus represents a commensal, colonizer or pathogen in the setting of CF. The underlying immune state, disease severity and treatment burden represent key host variables whilst fungal type, form, chronicity and virulence including the ability to evade immune recognition determines the pathogenic potential of a specific fungus at a particular point in time. Further research in this emerging field is warranted to fully elucidate the spectrum of disease conferred by the presence of fungi in the CF airway and the indications for therapeutic interventions.

Development of IgG antibodies to Exophiala dermatitidis is associated with inflammatory responses in patients with cystic fibrosis

BACKGROUND

The clinical importance of airway colonisation by the fungus Exophiala dermatitidis in patients with cystic fibrosis (CF) is unclear. We have previously shown that E. dermatitidis frequently colonises the airways of patients with CF. The aims of the present study were to determine whether patients who are colonised by E. dermatitidis have detectable fungal antigens in the circulation, develop anti-fungal antibodies, and show signs of inflammation and impaired respiratory function.

METHODS

We collected sputum and serum samples consecutively from 98 sputum-producing patients with CF aged more than 12 years. The serum samples were subjected to bacterial and fungal culturing and analyses for fungal antigens and inflammatory factors.

RESULTS

E. dermatitidis was recovered from 17 (17%) patients, the same isolation rate as for Aspergillus fumigatus. There were no difference regarding the levels of β-glucan in the sera from E. dermatitidis culture-positive and culture-negative patients with CF. Serological analysis revealed significantly higher levels of IgG antibodies to E. dermatitidis cell wall fragments in the E. dermatitidis culture-positive patients. Patients with higher level of E. dermatitidis IgG antibodies were more often colonised with non-tuberculous Mycobacteria, and less often with Staphylococcus aureus. The increased levels of IgG antibodies directed against E. dermatitidis were positively associated with higher white blood cell counts, increased erythrocyte sedimentation rate, pancreatic insufficiency, intravenous antibiotic treatment, and they were negatively associated with respiratory function (FEV1 % predicted). Overall, 4/17 Exophiala-positive patients were diagnosed as having symptomatic infection with E. dermatitidis and were treated with broad-spectrum azoles.

CONCLUSION

E. dermatitidis triggers antibody production and may cause significant airway infection in patients with cystic fibrosis.

Chronic pulmonary aspergillosis

Chronic pulmonary aspergillosis (CPA) is a group of consuming diseases usually presenting with prolonged and relapsing cough, dyspnoea and weight loss. Acute symptoms such as haemoptysis and bronchial or pulmonary haemorrhage may occasionally occur. CPA affects patients with underlying pulmonary conditions, for example, chronic obstructive pulmonary disease or mycobacteriosis or common immunosuppressive conditions such as diabetes. Precise epidemiology is unknown, and while prevalence is considered low the chronic and relapsing nature of the disease challenges the treating physician. Diagnostics largely rely on serologic Aspergillus precipitins and findings on thoracic computed tomography. The latter are manifold comprising cavity formation, pleural involvement and sometimes aspergilloma. Other markers for aspergillosis are less helpful, in part due to the non- or semi-invasive nature of these forms of Aspergillus infection. Various antifungals were shown to be effective in CPA treatment. Azoles are the most frequently applied antifungals in the outpatient setting, but are now compromised by findings of Aspergillus resistance. Long-term prognosis is not fully elucidated and may be driven by the underlying morbidities. Prospective registry-type studies may be suitable to systematically broaden our CPA knowledge base. This article gives an overview of the available literature and proposes a clinical working algorithm for CPA management.