Rapid detection of bacterial growth in blood cultures by bioluminescent assay of bacterial ATP.

A method for rapid detection of bacterial growth in blood cultures by bioluminescent assay of bacterial ATP was developed. Samples from blood cultures were treated with a blood-lysing detergent combined with an ATP-hydrolyzing enzyme to destroy blood cell ATP. Blood cell ATP which was bound to cell debris and escaped the ATPase activity was then separated from the bacteria on Percoll density gradients. Bacterial ATP from the bacterial layer was determined by the firefly bioluminescence system. In simulated blood cultures inoculated with 10 CFU of bacteria per ml of blood, bacterial ATP levels exceeded the detection limit (10(-10) M) after 6 to 10 h of incubation. This ATP level corresponds to approximately 10(4) CFU of bacteria per ml.