Use of 16s rRNA Gene Sequencing for the Identification of Viridans Group Streptococci

Streptococci belonging to the viridans group are gram-positive bacteria residing as commensals in the upper respiratory, gastrointestinal, and genital tracts in humans. Though they are largely known to be commensals, they may also cause life-threatening infections like infective endocarditis, septicemia, pyogenic infections, pneumonia, and meningitis. The viridans group streptococci (VGS) are usually identified by biotyping; however, species discrimination is not always possible by phenotypic characterization. We identified 53 isolates from blood cultures of patients with infective endocarditis and compared the results of biotyping with 16s rRNA gene sequencing for species identification. Organisms belonging to the mitis group were the most common. 16s rRNA gene polymerase chain reaction and sequencing were useful in identifying the etiological agents at the species level. S.oralis was the most common etiological agent.