280 DIFCO MANUAL 



B AGTO-TR YPSIN ( B 1 53 ) 



Bacto-Trypsin is a filter sterilized and carefully standardized desiccation of 

 tryptic enzymes. It is rehydrated by the addition of sterile distilled water. Bacto- 

 Trypsin is recommended for the neutralization of the antitryptic power of serum 

 and also for use in blood culture. 



Wright first made the observation that, in the treatment of suppurating wounds, 

 there may be a stage at which the infecting organisms grow luxuriantly and that 

 this stage was coincident with the lysis of the leucocytes. This destruction of the 

 white blood cells sets free the tryptic enzymes which neutralize the antitryptic 

 power of the blood and permits growth of the invading organisms. By utilizing 

 this principle Douglas and Colebrook^ evolved a method for blood culture work 

 which has been satisfactory. 



Owen^ recommended Trypsin-Beef Tea as an ideal medium for blood culture. 

 His medium consisted of 10 ml. Bacto-Trypsin added aseptically to 90 ml. sterile 

 Beef Broth. Typhoid and other organisms tend to show early and luxuriant 

 growth in this medium. An alternative method consisted of collecting the blood 

 in sterile tubes containing 0.5 ml. Bacto-Trypsin per milliliter of blood. The 

 blood and trypsin are mixed, incubated at 35-3 7 °G. for a short period and the 

 mixture is then smeared directly upon agar media. 



For tryptic digests of protein for the preparation of culture media, use Trypsin, 

 Dif CO, 1 : 250 as discussed above. For Rh Blood Grouping use Bacto-Trypsin 1 % 

 for Hemagglutination described below or Bacto-Trypsin, Difco, 1 : 250 discussed 

 above. 



Bacto-Trypsin is supplied in packages of one half dozen and one dozen vials 

 of 10 ml. each. 



1 Lancet, 2:181:1916. ^ J. Lab. Clin. Med., 2:198:1916-17. 



BACTO-TRYPSIN 1% (B454) 

 for Hemagglutination 



Bacto-Trypsin 1% for Hemagglutination is a carefully standardized water 

 soluble trypsin preparation designed especially for conditioning erythrocytes for 

 Rh determinations and other hemagglutination tests. 



Hubener^ and Thomsen^ first showed that enzymes present in certain bacterial 

 filtrates could activate latent red cell agglutinogens. Friendenreich^ referred to 

 this type of reaction as "T agglutination". Burnet, McCrae and Stone* observed 

 that filtrates from Vibrio cholerae modified the virus hemagglutination of human 

 red cells. Pickles^ discovered that such V. cholerae treated cells became specifi- 

 cally agglutinable in saline dilutions of "incomplete" anti-Rh sera. Morton and 

 Pickles^ noted that trypsin behaved similarly to culture filtrates in increasing the 

 sensitivity and specificity of red cells sensitized with "incomplete" antibody and 

 also that it enhanced the specific agglutination of other hemagglutinins in the 

 absence of any detectable antibody of the "incomplete" type. The authors used 

 the beneficial effect of trypsin on erythrocytes as the basis for an improved test 

 for Rh sensitization. 



Wheeler, Luhby and ScholF'^ and Wheeler and Taylor^ studied the effect of 

 trypsin and other enzymes on cells employed in Rh determinations and found 

 trypsin to be particularly suitable for conditioning erythrocytes for such tests. 

 The titers of anti-Rh sera were greater when determined with the trypsin- 

 modified cell technique than were those obtained with the albumin-tube technique 

 and in many cases the sensitivity of the titrations equalled that of the indirect 



