Lack of clinical relevance in routine terminal subculturing of blood cultures.

The usefulness of performing final blind subcultures of previously negative blood cultures was evaluated over a 21-month period. From over 14,000 blood culture bottles blindly subcultured after 7 days of incubation, only 12 potentially significant organisms were found. The finding of these 12 organisms did not influence patient care since in 11 instances the same organism had already been reported from prior positive bottles and in 1 instance the patient had already died. These results suggest that blind 7-day subcultures are of minimal value. Other factors that need to be considered before eliminating the final subculture are presented.