Studies on a Certain Spreading Factor Existing in Bacteria and Its Significance for Bacterial Invasiveness

Invasive strains of staphylococcus and streptococcus contain a soluble factor which markedly increases tissue permeability and enhances the infections produced by these organisms, by other bacteria, and by vaccine virus as well. The non-invasive strains of the same species of staphylococci and streptococci do not contain this factor. The enhancing substance elaborated locally by organisms passes into the circulating blood and bringing about a general increase of tissue permeability may act to enhance local infections elsewhere. The factor is similar in the phenomena it elicits to the spreading factor extracted from many animal tissues, especially from testicle.