Effects of penicillin and lysozyme on the immunofluorescent and precipitin reactivity of group D streptococci.

Damage to the cell wall by growth in the presence of penicillin or by treatment with lysozyme enhanced the immunofluorescent (fluorescent antibody, FA) reactivity to group D streptococci. The optimum concentration and time of treatment with lysozyme varied inversely with the initial FA reactivity of the strain. Speciation of the organisms by a series of biochemical and physiologic tests suggested that the differences in initial FA reactivity were species-related. Thus, S. faecalis strains were the most FA-reactive and most sensitive to lysozyme. S. faecium strains were less FA-reactive and lysozyme-sensitive. S. bovis strains proved to be least FA-sensitive and were most resistant to lysozyme. Treatment with lysozyme was also effective in preparing extracts of group D antigen from all three species for Lancefield grouping by the precipitin test. The lysozyme extracts, moreover, produced much stronger reactions than those made from comparable volumes of cells by the methods of Lancefield or of Rantz and Randall.