Isolation and characterization of nutritionally variant streptococci from animal sources

Ten nutritionally variant streptococci were recovered from clinical specimens submitted to the Kansas State University Veterinary Clinical Bacteriology laboratory over a 4-year period. Isolates were recognized visually on primary blood agar plates by their satellite growth around a previously overlaid Staphylococcus aureus culture. All isolates grew within 24 hours in Todd-Hewitt and heart infusion broths supplemented with 5% bovine fetal serum and 5% S aureus filtrate. They also grew anaerobically in supplemented broths within 48 hours. However, isolates did not grow aerobically or anaerobically in the absence of supplements up to a 7-day postinoculation period. As determined by the standard Kirby-Bauer technique, the isolates were highly susceptible to antimicrobial agents commonly recommended in veterinary medicine. The isolates did not react with the corresponding Lancefield group-specific antisera, as tested by the capillary precipitin test.