Prevalence, geographic risk factor, and development of a standardized protocol for fungal isolation in cystic fibrosis: Results from the international prospective study “MFIP”

Abstract

BackgroundFungi are increasingly recognized for their potential role in contributing to pulmonary damage in Cystic Fibrosis (CF). We therefore designed a prospective international study aimed at (i) determining the prevalence of fungi isolated from sputum samples collected from a large CF population, (ii) comparing the performance of different media used for fungal culture, and (iii) proposing a standardized protocol suitable for CF routine microbiology. MethodsAn international, consensually designed prospective study was set up (https://www.ecfs.eu/special-projects/mucofong-international-project). All centers worked according to the same protocol approved by Lille Ethical Committee. CF sputa were inoculated onto eight semi-selective media incubated at 37 °C or 25 °C–30 °C for 15 days, and inspected twice weekly for fungal growth. ResultsA total of 469 sputa were collected from patients at 18 European and one Australian CF centers. Positive cultures for fungal growth were significantly associated with patient ages. Aspergillus fumigatus was the most frequently isolated mold. We identified a growing European North-to-South gradient of Scedosporium prevalence, while yeasts, Aspergillus section Fumigati, Cladosporium and Penicillium were significantly more prevalent in the Northern regions. ConclusionsAccording to the CHi-squared Automatic Interaction Detector method, we propose a consensual protocol based on two media (YPDA or Sabouraud medium, and B(+) medium) to detect the main opportunistic molds in CF context; the use of an additional medium being recommended according to the patient's clinical status. This standardized protocol allows us to have an accurate overview of the respiratory mycobiome on the culturomic side in CF.