[Identification of Staphylococcus aureus by determining nuclease activity and using methods of multivariate...

A new quantitative method for the determination of the DNA-se activity of bacteria, based on the prevention of the clot formation of DNA with rivanol under the action of microbial DNA-ses, has been developed. The sensitivity of this method is 0.005-0.01 units of activity (1-2 ng) of the enzyme in a sample for 1 hour of incubation; the variation coefficient of the method is 8-9%. The use of this method has made it possible to reduce the time of the identification of S.aureus by 2-3 days in comparison with the commonly used methods. As revealed on the model of differentiation between S.aureus and S.epidermidis, the methods of multivariate statistical analysis (dispersion, discriminant, cluster methods) may find wide application for the discrimination of bacteria. They are supposed to be used for the interspecific identification of coagulase-negative staphylococci.