Isolation of Nocardia sp. from blood cultures in a teaching hospital.

To determine the clinical significance of the isolation of Nocardia sp. from blood cultures, clinical records of patients with bacteremia due to Nocardia sp. in our hospital from January 1986 to December 1990 were retrospectively reviewed. Eight patients had 9 blood cultures positive for Nocardia sp. Four of the isolates were identified as Nocardia asteroides. Only 2 of the patients had disseminated nocardiosis due to N. asteroides, and both were appropriately treated for Nocardia sp. In the other cases, isolation of Nocardia sp. was considered nonsignificant or undetermined, and all were clinically cured. Nocardia sp. may be an occasional contaminant of blood cultures. The significance of nocardemia is a matter of clinical judgment.