Effect on organism recovery rate from BacT/Alert blood cultures with reduced incubation period

This retrospective study evaluated 15,377 sets of BacT/Alert blood cultures to determine incubation time for blood cultures. Ninety-six per cent (1476) of total isolates signalled positive within five days and 56 isolates turned positive in five to seven days. Of the 56 organisms recovered between five and seven days, 49 were considered contaminants and seven were considered clinically significant. On assessing the medical records of the patients with the seven clinically significant isolates, it was determined that the clinical outcome would not have changed if these isolates were missed. We conclude that a five day incubation protocol reduces the recovery of skin contaminants while not significantly decreasing the recovery of clinically significant organisms. The data suggest that the incubation time can be further reduced but this policy will depend on the individual institution and their patient population mix.