An exploratory study of microbial diversity in sinus infections of cystic fibrosis patients by molecular methods.

Background: For the first time microorganisms in CF sinuses are investigated by molecular methods in response to an absence of anaerobes in CF sinus samples during a two-year period at the Copenhagen CF center.

Methods: Endoscopic sinus surgery was performed in 19 CF patients. DNA from intact bacterial cells was investigated by 16S rRNA gene analysis and quantitative PCR. Results were compared to culture-dependent routine diagnosis.

Results: Molecular methods showed a large microbial diversity, which included undetected anaerobes that may play a pathogenic role. Importantly, the culture methods did not always detect known CF pathogens. Quantitative PCR showed generally a higher abundance of classic CF pathogens e.g. Pseudomonas aeruginosa and Staphylococcus aureus compared with the anaerobe Propionibacterium acnes.

Conclusions: The results indicate that the culture methods in some cases may not be suitable as stand-alone method for this patient group, as diversity may be underestimated and important species undetected.