Physiological characterization of nutritionally variant streptococci.

Twenty-five isolates of nutritionally variant streptococci submitted to the Streptococcus Laboratory of the Center for Disease Control over a 2-year period were tested for growth requirements and for biochemical reactions. After they were recovered from storage in blood at -170 degrees C, all isolates grew within 48 h in both thioglycollate broth and Todd-Hewitt broth supplemented with 0.001% pyridoxal.HCl. They grew better in the latter, even though they all grew on unsupplemented infusion agar, anaerobe blood agar, and chopped meat-glucose medium. Biochemical patterns of the isolates resemble those of five viridans streptococcal species. Two isolates had patterns which did not resemble those of any viridans species. Biochemical reactions obtained with heart infusion broth base biochemicals and carbohydrate fermentation media compared favorably for an overall agreement rate of 86.5% for key tests. Lactic acid and acetic acid were the major fermentation products detected with gas-liquid chromatography.