An automated method for the detection of staphylococcal heat stable deoxyribonuclease in dairy products

An automated sandwich immunoassay with specific polyclonal antibodies for t he detection of Staphylococcus aureus thermostable nuclease (DNase) is desc ribed. To evaluate this assay, different quantities of purified S. aureus n uclease were added to dairy products. Additionally, staphylococcal counts a nd nuclease activity of milk samples inoculated with S. aureus were determi ned. Different extraction procedures were performed and compared. The resul ts indicated that the automated test was a reliable method for detecting DN ase activity in milk products. The procedure was completed in 2 h and detec ted 1 ng of DNase ml(-1.) Detection of the DNase was especially useful in c heeses and could be used to confirm positive enterotoxin results.