330 DIFGO MANUAL 



BAGTO-GOAGULASE PLASMA (B286) 



Bacto-Coagulase Plasma is a desiccated plasma recommended for the deter- 

 mination of coagulase production by staphylococci. The coagulase test is gen- 

 erally accepted as affording the best single criterion of potential pathogenicity of 

 staphylococci. The use of plasma dried on filter paper was first suggested by 

 Chapman.^ Foley^ also described a method for the desiccation of rabbit plasma 

 for use in the coagulase test. 



The ability of staphylococci to produce coagulase, an enzyme capable of clot- 

 ting plasma, was first reported by Loeb^ in 1903. Daranyi* indicated the practical 

 significance of this test, and since then numerous investigators have studied this 

 reaction to determine its relationship to the pathogenicity of staphylococci. 

 Chapman, Berens, Peters and Curcio^ in a study of coagulase and hemolysin pro- 

 duction by staphylococci, showed that strains producing coagulase were usually 

 pathogenic regardless of their hemolytic or chromogenic properties. Hallman^ 

 used coagulase production as a means of differentiating pathogenic from non- 

 pathogenic staphylococci isolated from the nares of a large number of individuals. 

 Cruickshank'' recommended that coagulase production be used as a test for the 

 pathogenicity of the staphylococci. Chapman, Berens, Nilson and Curcio^ stated 

 that coagulase production was the most reliable single test for the differentiation 

 of pathogenic from nonpathogenic staphylococci. Fairbrother^ concluded that 

 coagulase is formed only by pathogenic staphylococci and constitutes an impor- 

 tant criterion for the classification of these organisms into pathogenic and non- 

 pathogenic strains. Moss, Squires and Pitts^^ also showed the importance of 

 coagulase production in the determination of the pathogenicity of staphylococci. 

 Many other reports have been made showing the value of this test for the differ- 

 entiation of pathogenic from nonpathogenic staphylococci. 



The coagulase test may be performed using the tube method or the slide tech- 

 nique. Chapman, Berens and Stiles^^ described a tube coagulase test using a 1-3 

 dilution of fresh plasma. Incubation of the plasma and emulsified culture was at 

 37°C. and readings were made at one hour intervals for four hours. Generally, 

 rabbit plasma has been used in the various tests. Human plasma and human 

 whole blood have also been employed. Chapman^^ compared the value of human 

 plasma and human whole blood with rabbit plasma for testing the coagulating 

 power of staphylococci. He reported that rabbit plasma clotted more rapidly and 

 more firmly than did the human plasma or whole blood. Whole human blood, 

 however, clotted more easily than did the corresponding plasma. Chapman^^ 

 noted that not all human bloods were satisfactory and that other factors also 

 enter into a satisfactory coagulase test. There must be sufficient culture, grown 

 under satisfactory conditions, to react with a satisfactory plasma or whole blood. 

 Conditions that give a satisfactory coagulase test for the determination of patho- 

 genicity are discussed by Chapman.i-^-i^ Evans^^ used Bacto-Coagulase Plasma 

 and the tube technique in his studies of coagulase positive staphylococci. He re- 

 ported the 19 coagulase positive staphylococci comprised a rather homogenous 

 group. They fermented mannitol under anaerobic conditions and were able to 

 grow in a synthetic medium devoid of biotin. 



Bacto-Coagulase Plasma is well suited for the coagulase test. An outline for 

 the performance of the test follows : 



Dissolve the contents of one ampul (100 mgs.) in 3.0 ml. of distilled water. 

 Place 0.5 ml. of the plasma solution in a Wassermann tube supported in a rack. 

 Add two drops of a 16-24 hour Bacto-Brain Heart Infusion culture of the organ- 

 ism under test, or two drops of a Bacto-Brain Heart Infusion suspension of a 16- 

 24 hour culture on a slant of Heart Infusion Agar. Incubate at 37°C. Most 



