Effect of aerobic and anaerobic atmospheres on isolation of organisms from blood cultures.

Blood was cultured in two vacuum bottles containing Columbia broth. Filtered air was admitted to one bottle (aerobic); the unvented bottle was considered anaerobic. Cultures were incubated at 35 C until growth occurred or for at least 7 days. Of 744 organisms isolated, 50% were isolated from both bottles, 30% from the aerobic bottle only, and 20% from the anaerobic bottle only. These results indicate the need for use of both an aerobic and anaerobic bottle for blood cultures.