Streptococcus pseudopneumoniae, an opportunistic pathogen in patients with cystic fibrosis.

The pathogenic power of Streptococcus pseudopneumoniae has been specified over years, particularly in case of chronic respiratory diseases; S. pseudopneumoniae isolation has however not been characterized before in CF patients. Identification of S. pseudopneumoniae remains challenging due to the high simila-rity level between species of the Streptococcus mitis group. Twenty CF patients with S. pseudopneumoniae were included. Isolates initially identified by phenotypic routine methods were subjected to both recA sequencing and amplification of S. pseudopneumoniae specific markers. Microbiological and clinical data were reviewed for patients with confirmed S. pseudopneumoniae. Thirteen isolates actually belong to S. pseudopneumoniae. S. pseudopneumoniae was associated with pulmonary exacerbation in 46% of the patients, either as the sole pathogen or as part of a polymicrobial infectious process. S. pseudopneumoniae has to be considered as an additional opportunistic pathogen in CF and additional studies are needed to increase knowledge of its epidemiology and clinical significance in CF.