Patients with Cystic Fibrosis have Higher Rates of Fungal Detection in Their Respiratory Tracts when They Use Selective Fungal Culture Media

Abstract

Fungi have become more common in the respiratory tracts of people with cystic fibrosis (CF). However,
the majority of clinical facilities in the United States do not regularly conduct fungal surveillance, which
could result in an overestimate of the problem's actual prevalence. We used standard bacterial and
selective fungal culture media, such as Sabouraud dextrose agar with gentamicin (SDA), inhibitory
mold agar (IMA), and brain heart infusion (BHI) agar with chloramphenicol and gentamicin, to compare
the rates of detection for clinically important fungi (CIF), which are defined as Aspergillus,
Scedosporium, and Trichosporon species and Exophiala dermatitidis, in CF sputa. We reported how
common these fungi were in a population of adults with cystic fibrosis. From 211 distinct subjects, 487
CF respiratory samples were gathered. CIF was found in 184 samples, or 37.8%. In bacterial culture
medium, only 26.1% of CIF-positive samples were recognized; in contrast, higher rates of fungal
identification were seen in IMA (65.8%; P < 0.001), SDA (64.7%; P = 0.005), and BHI agar (63.0%; P =
0.001). Aspergillus and Scedosporium species prevalences were 40.8% and 5.2%, respectively, higher
than the 20.4% and 1.9% nationally reported prevalences. Longer incubation times and selective fungal
culture media produced greater rates of CIF detection in CF sputum samples than those found in
bacterial culture medium, which led to an underdetection of fungi by bacterial culture alone. Using
selected fungal culture media may improve the estimation of fungal prevalence in CF, which could lead
to significant clinical decisions.