["Clumping factor"-reactions using staphylococci after their extraction with guanidiniumchloride (author's transl)].

Staphylococci of strain K 807 (ATCC: 31243) have much "clumping factor" (CF) on their surface. Extraction of the staphylococci with 6 M guanidinium chloride, removed all soluble substances, including coagulase, without reduction in CF-activity. The extracted staphylococci proved to be most suitable for the quantitative determination of fibrinogen and fibrin degradation products in a microtiter procedure (fig. 2). The CF-test with staphylococci of strain K 807 was more sensitive compared with the hitherto used strain Newman D2C (table 1). After staining with "Astrazonrot (BBL)" no loss of CF occurred. With the stained staphylococci the CF-reactions became more distinctly visible and gave sharp endpoints.