ABSTRACT: The recent identification of Streptococcus pseudopneumoniae (pseudopneumococcus) has complicated classification schemes within members of the "mitis" streptococcal group. Accurate differentiation of this species is necessary for understanding its disease potential and identification in clinical settings. This work described the use of competence-stimulatory peptide ComC sequence for identification of S. pseudopneumoniae. ComC sequences from clinical sources were determined for 17 strains of S. pseudopneumoniae, S. pneumoniae, and S. oralis. An aditional 58 ComC sequences from a range of sources were included to understand the diversity and suitability of this protein as a diagnostic marker for species identification. We identified three pherotypes for this species delineated CSP6.1 (10/14, 79%), CSP6.3 (3/14, 21%) and SK674 (1/14, 7%). Pseudopneumococcal ComC sequences formed a discrete cluster within those of other oral streptococci. This suggests that comC sequence could be used to identify S. Pseudopneumoniae, thus simplifying the study of the pathogenic potential of this organism. To avoid confusion between pneumococcal and pseudopneumococcal pherotypes, we have renamed the competence pherotype CSP6.1 formerly reported as an "atypical" pneumococcus to CSPps1 to reflect its occurrence in S. pseudopneumoniae.
Journal of Clinical Microbiology 03/2012; · 4.15 Impact Factor