Emergence of persistent Aspergillus terreus colonisation in a child with cystic fibrosis

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Cystic Fibrosis (CF) is the most common inherited life shortening condition affecting Caucasians. CF is characterised by mutations in the CF transmembrane conductance regulator (CFTR) gene, which codes for an ATP-driven pump that transports sodium and chloride ions across epithelial surfaces [1]. CF is a multiple organ disease; however up to 95% of morbidity and mortality is due to pulmonary infection. The CF lung has impaired mucociliary clearance and a build-up of thick mucus which creates an ideal environment to facilitate microbial colonisation. Excessive neutrophil recruitment and enhanced inflammation ensue which causes airway epithelial cell damage, decline in lung function and eventual respiratory failure. Isolation of filamentous fungi, in particular Aspergillus spp. is common in respiratory secretions from CF patients [2]. Aspergillus terreus is the third most common filamentous fungus isolated from CF adult airway samples, being detected in 1.9 to 6.2% of CF patients [3,4]. In our clinic, 3 of 159 paediatric CF patients tested were A. terreus positive which is in line with the published literature on adults with CF (unpublished data). A. terreus has been reported to cause ABPA [5,6], infective endocarditis [6], pulmonary mycetoma [6] and invasive aspergillosis (IA) [7]. Until recently Aspergillus species identification was not thought to be therapeutically important; however different species within the genus can exhibit varying levels of antifungal drug resistance [8] and virulence in in vivo infection models [9]. Invasive disease caused by A. terreus can be as severe as IA caused by Apergillus fumigatus however A. terreus is inherently resistant to Amphotericin B [10]. Additionally IA caused by A. terreus is associated with long-term persistence of conidia and liver degeneration [11]. For these reasons A. terreus has the potential to cause complications post-transplant for people with CF. Here we present a case of a child with CF with a polymicrobial community in the airways among which A. terreus emerged and persisted as a dominant species.