Effects of Enzymatic Digests of DNA on Staphylococci. ∗

Abstract

Summary

The multiplication of coagulase-positive staphylococci was found to be stimulated by a factor present in enzymatic digests of DNA, which previously had been shown to stimulate DNA synthesis and multiplication rates of other gram-positive bacteria, regardless of the source of DNA used. Coagulase-negative variants do not respond and the presence of the DNA digest factor therefore enhances population changes favoring rapid establishment of coagulase-positive organisms in initially predominantly coagulase-negative populations. On the basis of studies with chelated media it was concluded that, by virtue of cell lysis and nuclease production, a DNA digest factor can accumulate naturally in non-chelated, aging staphylococcal cultures containing at least a few coagulase-positive cells. An enhancement by DNA digest of localized lesions that develop following subcutaneous injection of staphylococci into mice also was noted. The implications of these findings for understanding the unusual direction of population changes of staphylococci in vitro as well as problems of pathogenesis and therapy have been discussed.