Relationships among the results of coagulase, staphylococcal toxin, and thermonuclease tests on staphylococci from cow milk.

Production of staphylococcal alpha- or alpha-beta-toxins correlated well with production of coagulase or thermonuclease (or both) in 203 Staphylococcus aureus isolates from milk and should be reliable indicators of S. aureus in the absence of Staphylococcus intermedius. Failures to produce toxin, tube coagulase, or thermonuclease occurred in only 1 to 2% of S. aureus. Evidence of beta- or alpha-beta-toxins was not found among 321 other staphylococci isolated from milk. A few coagulase- or thermonuclease-positive isolates not producing beta- or alpha-beta-toxins were found among the Staphylococcus hyicus isolates.