Activation of Coagulase Clotting by Trypsin Inhibitor

Abstract

Egg white trypsin inhibitor activated coagulase clotting when added to a final concentration between 2 and 60 mg/ml. The greatest increase in clotting rate was observed in reaction mixtures containing the lowest concentrations of serum and plasma. Maximal activation was reached with 40 mg of trypsin inhibitor per ml when either serum or plasma was used as the source of coagulase-reacting factor (CRF). The increased rate of clotting is partly due to inhibition of plasmin. Freezing and thawing reduced plasma clotting inhibition. Soybean trypsin inhibitor also activated the coagulase reaction. The increased rate of clotting was observed with a coagulase preparation from organisms which produced plasminogen activators and with the culture supernatant fraction from organisms which did not activate plasminogen to plasmin. The tube test for coagulase could be made more sensitive for some strains of staphylococci by increasing the concentration of CRF (added as plasma or serum) by adding trypsin inhibitor, or both.

Significance of Staphylocoagulase in Food Microbiology: A Review

“…They found the reaction time decreases with increases in plasma concentration until a concentration of about 4 0 %~ Stutzenberger et al (1966) concluded t h a t the relative activity of the coagulase increases with the plasma concentration up to a concentration of 2?6 as determined nephelometrically. This result differed sharply from those of Orth et al (1969), but it must be clarified that the source of plasma as well as the assay procedure were completely different. The activity of the reaction also increased with the fibrinogen concentration up to about 2.5 mg/ml.…”

“…The plasmin thus formed causes fibrinolysis (proteolytic degradation of the fibrinogen clot) which results in the disappearance of the clot observable during coagulase test a n d therefore can lead to false negative reactions (Orth et al 1971). This activity can be prevented by adding soybean trypsin inhibitor into the assay system (Hutchinson 1962;Orth et al 1969).…”

“…To avoid the occurrence of false negative results due to fibrinolysis during the tube coagulase testing, taking readings periodically for up to 6 h a n d then reexamination after 24 h h a s been recommended (Baer et al 1976;Finegold et al 1978;MacFaddin 1981). Orth et al (1969 reported that the incorporation of trypsin inhibitor (egg white or soybean) into coagulase testing was useful not only for protecting against false negative reactions but also in reducing the reaction time of coagulase produced by organisms which did not activate plasminogen to plasma.…”

Comparison of Animal Sera for Suitability in Coagulase Testing 1

“…A partially purified protein preparation from S. aureus 265-1 was used as the source of SK and MF. This material possessed coagulas activity; its preparation was described elsewhere (14). Serum and plasma.…”

Polymyxin-Coagulase-Mannitol-Agar

“…Initially, 0.35-ml eluant fractions were collected, egg white trypsin inhibitor (EWTI, Calbiochem trypsin inhibitor; egg white, B grade, each milligram inhibits approximately 0.7 mg of trypsin) was added to give a final concentration of 40 mg/ml, and the fractions were assayed for CRF by determining coagulase activity at 15-min intervals by the method of Orth et al (9). Fibrinolysis was determined by making periodic readings for as long as 24 hr and recording the degree of fibrin gel formation by using the method of Turner and Schwartz (13).…”