The Role of Gene Analysis for Species Determination of Viridans Streptococci

Species identification of viridans streptococci has often been a difficult task in clinical laboratories. A battery of biochemical tests performed in most laboratories may categorize the organism into a group, but it has not proven to be satisfactory for differentiating among species within a group. The incidence of infection caused by viridans streptococci has been increasing, and thus methods for accurate species identification of these streptococci are needed. Molecular or nucleic acid-based approaches have become an important component of organism identification, in which the 16S rDNA sequencing is commonly used for identification of bacteria. Unfortunately, 16S rDNA sequencing cannot differentiate among some closely related species of viridans streptococci. Other genes have been investigated for use in species determination, and the applicability of some of these targets in clinical laboratories will be discussed.