Some properties of coagulase-negative deoxyribonuclease-producing strains of staphylococci from human infections.

Twenty-seven coagulase-negative and deoxyribonuclease-positive staphylococci were isolated from more than 3000 specimens from human infections. The strains were tested by conventional biochemical tests and by simple agar plate assays for production of different extracellular enzymes and toxins. Three strains were lysed by S. epidermidis phages and 7 strains by S. aureus phages. All strains produced thermolabile nuclease but only 21 strains produced thermostable nuclease. The investigated strains belonged to a heterogeneous intermediate group sharing characters of S. aureus and S. epidermidis. Tests for production of coagulase and thermostable nuclease should be used in the classification of these intermediate strains in diagnostic bacteriology.