Recognition of Group D Streptococcal Species of Human Origin by Biochemical and Physiological Tests

The speciation of 262 strains of group D streptococci isolated from human sources is described. One hundred forty-two isolates from blood cultures were included; 96 of these were submitted as isolates from clinical cases of subacute bacterial endocarditis. The results show that 98 Streptococcus faecalis, 29 S. faecalis var. zymogenes, 44 S. faecalis var. liquefaciens, 27 S. faecium, 13 S. durans, 44 S. bovis, and 7 unspeciated S. bovis-like group D isolates were identified. No S. faecium var. casseliflavus, S. equinus, or S. avium (group Q streptococci) were identified among the human isolates. The speciation procedures and techniques are detailed. The procedures and limitations of the tests used are discussed. Ninety-eight percent of the 262 strains were speciated by a spectrum of tests that allowed us to recognize atypical as well as typical strains within species.