Clinical associations and prevalence of Scedosporium spp. in Australian cystic fibrosis patients: identification of novel risk factors?

Risk factors for the association of Scedosporium in cases of cystic fibrosis (CF) and its clinical implications are poorly understood. Clinical, lung function and laboratory data of adult CF patients in Sydney (April 2008-March 2009) were prospectively analysed for such risk factors. Expectorated sputa were cultured for bacteria and examined for fungi using standard mycological and Scedosporium-selective media, and by an internal transcribed spacer region-targeted multiplex PCR assay. Scedosporium spp. (n = 4 each of Scedosporium prolificans, Scedosporium aurantiacum and Pseudallescheria boydii/ Scedosporium apiospermum complex [non-S. aurantiacum]) were recovered from 12 of 69 (17.4%) patients. Samples of 11 of the patients yielded isolates on Scedosporium- selective media (vs. 6 [8.7%] by non-selective culture) and one additional patient was noted by PCR. Of these patients, 83.3% were co-colonized with other moulds, most frequently Aspergillus fumigatus. Colonization was not associated with best FEV₁/predicted, corticosteroid or antifungal therapies. By univariate analysis, patients with Scedosporium colonization were significantly less likely to be colonized with mucoid Pseudomonas aeruginosa (P = 0.025), while prior therapy with antistaphylococcal penicillins was a risk factor for colonization (P = 0.045). Bacterial colonization and antimicrobial exposure likely influence Scedosporium colonization, which is optimally detected with selective media. Studies are required to confirm independent risk factors for Scedosporium colonization and to determine its impact on lung disease.