106 DIFGO MANUAL 



Media similar to the one described by Dubos have been used by numerous 

 investigators for various pure culture studies of the tubercle bacillus, as, for 

 example, the work of Middlebrook^° and others. Such a medium is excellent for 

 carrying stock cultures of M. tuberculosis, as organisms maintain their viability 

 without change in phase of virulence for long periods of time. It also offers a 

 suitable means of running chemotherapeutic screening tests and the testing 

 of the sensitivity of the tubercle bacillus to antibiotics and other materials. 



Wolinsky and Steenken^^ and Bernstein, D'Esapo and Steenken^^ ^sed Dubos 

 Medium and modifications of this liquid medium in testing the resistance of 

 tubercle bacilli to streptomycin. Wong, Hambly and Anderson^^ xj^sed a modifi- 

 cation of the Dubos and Davis medium to demonstrate sensitivity of M. tubercu- 

 losis to subtilin. Beattie^* compared hydrochloric acid and trisodium phosphate 

 treatment of sputa, followed by culturing on the fluid medium of Dubos and on 

 Petragnani medium. Her results indicated no superiority of either method of 

 treatment of sputa, however, the evidence suggested that the use of trisodium 

 phosphate may adversely affect the growth of the tubercle bacilli. Both the liquid 

 and solid medium were equally effective in the cultivation of M. tuberculosis in 

 this study. 



Mollov, Hill and Oshinsky used Dubos^^ medium for the routine isolation and 

 cultivation of M. tuberculosis. They added 10 units of penicillin per ml. of the 

 Dubos liquid medium as a selective agent. Types of specimens examined were 

 sputum, gastric contents, pleural fluid, spinal fluid and urine. The necessity of 

 making smears to determine the presence of the tubercle bacillus was stressed 

 and they streaked on Petrick's medium to detect tubercle bacilli and show 

 typical colony characteristics. These authors also found the Dubos liquid medium 

 to be helpful in the determination of sensitivity and resistance of the tubercle 

 bacilli to streptomycin. 



Bacto-Dubos Broth Base enriched with Bacto-Dubos Medium Albumin or 

 Bacto-Dubos Medium Serum will give growth in from 3-5 days from a 10~^ mg 

 inoculation of M. tuberculosis and in 10-15 days using 10"^ mg inoculum. The 

 medium prepared with Bacto-Dubos Medium Serum will generally give a more 

 luxuriant growth and initiate growth from a smaller inoculum than that en- 

 riched with Bacto-Dubos Medium Albumin. Growth is generally more diffuse 

 in media prepared with the Albumin enrichment, while with the Serum enrich- 

 ment the growth is granular. Bacto-Dubos Medium Albumin is a 5.0 per cent 

 solution of albumin fraction V from bovine plasma in normal saline and contains 

 7.5 per cent Bacto-Dextrose. Bacto-Dubos Medium Serum is beef serum with 7.5 

 per cent Bacto-Dextrose. Both solutions are filter sterilized. 



The early and luxuriant growth of tubercle bacilli in media prepared with 

 Dubos Broth Base and Dubos Medium Serum make it ideal for the cultivation 

 and study of pure cultures of these organisms. It is also recommended for 

 culturing spinal, pleural and peritoneal fluids likely to harbor the tubercle 

 bacillus in pure culture. Growth is readily visible. In sensitivity tests where the 

 presence or absence of growth is the determining factor, the medium prepared 

 with Bacto-Dubos Medium Serum may be recommended. For tests requiring 

 turbidimetric determinations for quantitative growth, mouse or guinea pig 

 inoculation work or other techniques requiring a readily dispersible growth, the 

 medium should be prepared with Bacto-Dubos Medium Albumin. 



The microscopic appearance of tubercle bacilli, when viewed with a 16 mm. 

 objective, is quite typical on this medium. The organisms appear in irregular 

 clumps or tangled filaments rather than as individual cells. Edges of these 

 clumps, examined with the oil immersion lens, show typical acid-fast bacilli. If 

 it is desired to grow tubercle bacilli from concentrated sputa or other pathologi- 

 cal material it is difficult to distinguish macroscopically between tubercular 



