In order to further investigate a potential link between respiratory viruses and P. aeruginosa infections, we screened respiratory material of CF patients using a multiplex PCR based assay. In line with a similar study, we could detect mainly human rhinovirus and to a much lesser extent RSV, Influenza-A/B, Adenovirus or Parainfluenza Virus (55, 56). Interestingly, CF patients intermittent infected with P. aeruginosa had a higher risk for hRV infection (Odds ratio = 2.374) and displayed higher virus loads in the sputum compared to P. aeruginosa negative or chronically infected patients. However, this observation could just be made if material of the lower respiratory tract (sputum) was analyzed. If also samples from the upper airways (nose, throat) were considered no statistical difference between all groups could be seen. Considering that hRV normally infects the upper respiratory tract, increased detection rates in the lower respiratory airways in P. aeruginosa positive individuals might be an indicator for a higher disease burden of hRV infection, similar to the situation in asthmatic or COPD patients (20).