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An Improved Method for the Serotyping of Free Coagulase from Staphylococcus aureus
Author(s) -
Tajima Yutaka,
Nagasawa Zenzo,
Tanabe Ichiro,
Yamada Hisashi,
Kusaba Koji,
Tadano Jutaro
Publication year - 1992
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1992.tb02127.x
Subject(s) - coagulase , fibrin , magnetite , fibrinogen , staphylococcus aureus , microbiology and biotechnology , chromatography , viscosity , serotype , chemistry , biology , staphylococcus , materials science , immunology , biochemistry , bacteria , composite material , paleontology , genetics
The serotyping of free coagulase, one of the most reliable ways to identify strains of Staphylococcus aureus , and widely employed in Japan, has been improved by adding magnetite sand to the reaction mixture. Culture medium supernatant and a type‐specific antibody are mixed in a well of a microtiter plate, and plasma‐enriched bovine fibrinogen is treated with magnetite sand. The use of tranexamic acid and gum arabic in the reaction mixture also increases the sensitivity of the reaction. Finally, the plate is placed on a magnetic stirrer. If the type of the coagulase corresponds to that of the antibody, no clot formation will occur, and this is easily confirmed by the movement of the sand. Although the amount of reaction mixture required is much less than that for the conventional tube method, our new method is able to detect slight increases in viscosity of the reaction mixture due to fibrin formation even before complete clotting occurs, thus providing very high sensitivity. Clot formation can also be judged by observing a turbid mass of fibrin in the well (Hwang's method), but this approach is a little slower than our method involving immobilization of magnetite sand.