Introduction
Progressive lung injury in cystic fibrosis (CF) can lead to chronic colonization with bacteria and fungi.For bacteria safety measures to prevent patient-to patient transmission during coughing are taken. Fungal cross-infection is thought not to occur, however no studies have examined this so far. The objective of this study is to evaluate if secretion of Aspergillus fumigatus occurs during 	coughing in CF patients.

Material and Methods:
 During two visits, adult CF patients colonized with A. fumigatus were asked to cough on two different agar plates. Agar plates used were sabouraud dextrose agar with chloramphenicol and columbia III agar. Sputum samples were collected simultaneously and used as measure of concomitant colonization.If A. fumigatus was cultured in both the cough plate and the sputum sample, short-tandem-repeat (STR) genotyping of all colony-forming-units was performed. Identical STR genotypes on cough plate and sputum sample were deemed as definitive proof of secretion.

Results:
Thirty cough-plates and sputum cultures were collected from 15 patients. Eighteen sputum samples were positive with A. fumigatus.  
Three out of 18 (17%) positive sputum cultures also showed A. fumigatus on the cough plate. Transmission frequencies of bacterial pathogens were: Pseudomonas aeruginosa, 67% (10 out of 15); Staphylococcus aureus, 19% (3 out of 16); Stenotrofomonas maltophilia, 0%. Cough secretion of A. fumigatus was proven in 2 patients. 

Conclusions:
1. Cough secretion of A. fumigatus  occured in colonized CF patients. 2. Patient-to-patient transmission is theoretically possible. 3. Additional research is necessary to determine whether additional infection prevention measures are needed.

7 / Transmission-frequency of Aspergillus fumigatus in cystic fibrosis patients through coughing