Immunofluorescence Examination of Typical Staphylococcus aureus Variants and L-forms for Clumping Factor

Abstract

SUMMARY: Encapsulated coagulase-positive staphylococci which do not clump with fibrinogen possess the clumping factor antigen as well as other cell-wall antigens characteristic of Staphylococcus aureus. Variants which were negative for both coagulase and clumping factor not only lacked the clumping factor antigen but also other S. aureus surface antigens. L-forms did not remove clumping inhibiting antibody from S. aureus antisera. Antisera which were relatively high in clumping-inhibiting antibodies, but low in agglutinins, gave no fluorescence with coagulase-negative, clumping factor-negative variants or L-forms. The clumping factor, probably a cell-wall component of S. aureus, is absent in the penicillin-induced, stable L-form.