262 DIFGO MANUAL 



B AGTO-TR YPTOSE ( B 1 24) 



In the course of a series of studies on the growth requirements of the Brucella, 

 a peptone which was particularly suited for these organisms was developed. This 

 peptone was designated as Bacto-Tryptose. In the absence of meat infusion, 

 Bacto-Tryptose is recommended for use in an agar medium with sodium chloride 

 and dextrose for the propagation of all types of Brucella.'^ With suitable dyes this 

 medium also proved satisfactory for the isolation and differentiation of Brucella 

 strains. Many of the irregular results obtained on liver infusion media are elimi- 

 nated by the use of culture media containing Bacto-Tryptose. 



Subsequent investigation of the nutritive properties of Bacto-Tryptose demon- 

 strated that culture media prepared with this peptone were superior to the meat 

 infusion peptone media employed for cultivation of the streptococci, pneumo- 

 cocci, meningococci and other fastidious pathogenic bacteria. A 2 per cent solu- 

 tion of Bacto-Tryptose with 0.05 per cent dextrose to replace muscle sugars, is an 

 excellent substitute for the infusions plus peptones generally employed in culture 

 media for the propagation of many of the organisms which grow with difficulty 

 even on infusion media. Other ingredients are added as usual to this solution to 

 make the complete medium. 



An agar medium prepared with 2 per cent Bacto-Tryptose and 0.5-0.8 per 

 cent sodium chloride, without tissue infusion, is an excellent general culture 

 medium and base for Blood Agar. This peptone is excellently suited for the 

 preparation of a base for Blood Agar as was reported by Gasman. --^ 



A medium containing 2 per cent Bacto-Tryptose, 0.5 per cent sodium chloride, 

 0.3 per cent disodium phosphate and 0.2 per cent dextrose may be used as a 

 liquid medium for blood culture work. A discussion of Bacto-Tryptose Phosphate 

 Broth is given on page 100. Excellent growth of many fastidious organisms occurs 

 in this liquid medium. As in the case with other liquid substrates, the medium 

 is greatly improved by the addition of 0.1 per cent agar. A medium consisting of 

 1 per cent Bacto-Tryptose, 0.5 per cent sodium chloride and 0.1 per cent di- 

 sodium phosphate is an excellent base free from carbohydrate to which a suitable 

 indicator and appropriate sugars may be added for studying the fermentation 

 reactions of the pathogenic bacteria. 



Tryptose has proved of value in media for the detection of coliform bacteria. 

 Darby and Mallmann*'^ developed a Lauryl Tryptose Broth that gave a high 

 colon index and could be used as a presumptive as well as a confirmatory test 

 for members of the coliform group. This medium was investigated by Levine,^ 

 McCrady'^ and Perry and Hajna^ and is recommended for use in the standard 

 tests for the coliform group as specified in "Standard Methods for the Examina- 

 tion of Water and Sewage"^ of the American Public Health Association. A 

 complete discussion of this medium is given under Bacto-Lauryl Tryptose Broth 

 on page 39. Perry and Hajna used Bacto-Tryptose in their modified Eijkman 

 Lactose Medium for the differentiation of Escherichia coli from other coliform 

 bacteria. This medium is discussed on page 44 under Bacto-Eijkman Lactose 

 Medium. 



The usefulness of Bacto-Tryptose in a large variety of bacteriological studies is 

 demonstrated by the many references to it in the literature. Among these may be 

 cited those of Schneiter et al.^° and Wells et al.^^ in the bacteriological examina- 

 tion of air, Pike^^ ^nd Parker and Callen^^ in their studies of media for the isola- 

 tion of streptococci and many others. 



Bacto-Tryptose was employed in preparing the media used in Castaneda's 

 double medium method^* for the isolation of Brucella from the blood. A detailed 



