Rapid identification of Staphylococcus aureus in blood cultures by thermonuclease testing

The detection of thermonuclease activity in 86 blood culture samples containing gram-positive cocci showed 100% correlation with the subsequent identification of the isolate as Staphylococcus aureus by the coagulase test. No positive thermonuclease results were found with 66 samples containing coagulase-negative staphylococci and 56 samples containing other gram-positive organisms. The thermonuclease test provides a rapid, reliable method to identify S. aureus in blood cultures.