Detection of Occult Scedosporium Species in Respiratory Tract Specimens from Patients with Cystic Fibrosis by Use of Selective Media

Abstract

Respiratory samples from cystic fibrosis outpatients were cultured on Sabouraud's dextrose agar (SABD) containing antibiotics, Mycosel, and Scedosporium-selective medium (SceSel؉). Thirty-two (14.7%) of 218 specimens from 11/69 (15.9%) patients yielded a Scedosporium sp., most frequently Scedosporium aurantiacum (17/218). Scedosporium was recovered on SceSel؉, Mycosel, and SABD from 90.6%, 50.0%, and 46.9% of the specimens tested, respectively.Opportunistic molds are increasingly isolated in respiratory specimens from children and adults with cystic fibrosis (CF) (17). Scedosporium species are the second most frequently recovered fungi, after Aspergillus fumigatus (4). Although invasive scedosporiosis is reportedly rare in CF prior to lung transplantation (11), colonization may be a risk factor for invasive disease posttransplantation, with associated high mortality (14,19,(21)(22)(23). The impact of airway colonization by Scedosporium spp. on respiratory function has not been studied; nevertheless, as Scedosporium spp. are resistant to many antifungal agents, colonization may be a relative contraindication to transplantation (18).Isolation of multiple fungi from respiratory specimens is frequent (19). The prevalence of non-Aspergillus molds may be underestimated due to overgrowth of Aspergillus spp. on routine media (4). A medium (SceSelϩ) containing the selective antifungal agents dichloran and benomyl has been described for the recovery of Scedosporium from environmental samples (16,20), but its utility in detecting Scedosporium spp. in clinical specimens has not been determined. No commercial preparation is available. Scedosporium spp. have been identified previously in respiratory specimens from 8.6 to 10% of CF patients (4, 24). These data were published prior to recent taxonomic reassignments of Scedosporium spp. (9, 10), and selective media were not used. We therefore compared the performance of two general media and one selective medium for the isolation of Scedosporium spp. from respiratory specimens and prospectively investigated the frequency and species distribution of Scedosporium in CF patients. Plates were incubated at 30°C in air and examined twice weekly for 28 days. Suspicious colonies were identified to the species level (Aspergillus and Scedosporium spp.) or the genus level (other molds) by standard morphological/ phenotypic methods (7, 9, 10). Scedosporium strains were identified as Scedosporium prolificans, S. aurantiacum, or S. apiospermum by restriction fragment length analysis of the internal transcribed spacer (ITS) region (8). ITS sequence analysis was performed on all S. apiospermum isolates and selected S. aurantiacum isolates (8).Samples (n ϭ 218) were received from 69 patients. Filamentous fungi were detected in 142 samples (65.1%) from 56 patients (81.2%; Table 1). The majority of the fungi (83.9%) were recovered following 6 days of incubation, and 95.1% were recovered following 10 days. Aspergillus spp. were the most frequently recovered, with A. fumigatus isolated in 45.4% of t...

Isolation of Scedosporium apiospermum (Teleomorph: Pseudallescheria apiosperma) from an Acute Myeloid Leukemia Patient

“…kolonizasyona predispozisyon oluşturması ve etken virülansına özel hasta gruplarının tanımlanması (tatlı suda boğulma olaylarında beyin apsesi oranlarının artması vb.) ile hayatı tehdit eden, önem kazanan fungal patojenler arasında kabul edilmeye başlanmıştır 4,[7][8][9][10] . Risk grubu hastalarda çoğunlukla ön planda Aspergillus ve Candida izolasyonlarının olması, daha yavaş üreyen Scedosporium spp.…”

Development and Validation of a Multiplex PCR for Detection of Scedosporium spp. in Respiratory Tract Specimens from Patients with Cystic Fibrosis

“…The emergence of Scedosporium infections in Australia has been highlighted in earlier reports describing the species distribution, clinical epidemiology, and outcomes (1,2,7,10,16). Further, a nationwide population-based study uncovered a substantial number of infections due to S. aurantiacum and identified an association between isolation of this species and the presence of chronic lung disease (16).…”

“…Long-term colonization with these fungi has been reported in patients with structurally abnormal respiratory airways, including those with cystic fibrosis (CF) (1,2,6,9). Invasive fungal infection is rare in CF patients prior to lung transplantation (15), yet Scedosporium colonization may be a risk factor for invasive infection posttransplantation.…”

“…in clinical specimens, however, are insensitive and time-consuming, as culture from sputum samples may require up to 14 days to produce fungal growth adequate for morphological identification (1,5). A number of molecular detection and identification methods for Pseudallescheria/Scedosporium have been reported (3,4,19,20,21,29).…”

“…The performance of the assay was then evaluated using sputum specimens from adult patients with CF. (1). Plates were incubated at 30°C and examined twice weekly for 28 days.…”