DEHYDRATED CULTURE MEDIA 77 



fastidious streptococci, pneumococci, meningococci, and other pathogenic 

 microorganisms. 



Peptones now have been developed which in a 2 per cent concentration satis- 

 factorily replace the infusion and peptone portion of infusion media for many of 

 the fastidious pathogens. These peptone media will be discussed in the section, 

 Peptone Media, Without Infusions, on pages 99-130. 



A guide for the selection of culture media listed in this section is given on 

 pages 26, 27 and 28. 



BACTO 



BRAIN HEART INFUSION (B37) 



DEHYDRATED 



Calf Brains, Infusion from 200 g. 



Beef Heart, Infusion from 250 g. 



Proteose Peptone, Difco 10 g. 



Bacto-Dextrose 2 g. 



Sodium Chloride 5 g. 



Disodium Phosphate 2.5 g. 



Bacto-Brain Heart Infusion is a liquid infusion medium recommended for the 

 cultivation of streptococci, pneumococci, meningococci, and other organisms 

 generally considered difficult to cultivate. Virulence, antigenicity, and other 

 serological characteristics of organisms are quite uniformly maintained when 

 grown on Bacto-Brain Heart Infusion. This medium is especially adapted for 

 blood culture work. Bacto-Brain Heart Infusion, solidified with agar is recom- 

 mended for the isolation of pathogenic fungi, and this medium is discussed in 

 detail on page 90. 



Rosenow^ devised an excellent culture medium for the streptococci by adding 

 pieces of brain tissue to Dextrose Broth. In this medium he was able to secure 

 excellent results in culturing organisms from focal infections in the teeth or 

 other tissues. Hayden,^ using the same procedure as Rosenow, but adding 

 crushed marble to the medium, reported that this medium was favorable for 

 the growth of organisms from infections of the teeth, especially those showing 

 a close relationship with eye infections. 



Bacto-Brain Heart Infusion is prepared to duplicate the results obtained by 

 Rosenow and Hayden. It contains the essential nutriments of their medium and 

 possesses the advantage of yielding an easily prepared clear medium. An infusion 

 of brains has replaced the nutritive value of the brain tissue, disodium phosphate 

 replaced the buffer calcium carbonate, and if desired 0.1 per cent agar may 

 be added to the medium giving conditions of oxygen tension similar to those 

 produced by the tissue. The addition of a small amount of agar (0.1-0.2 per 

 cent) to Brain Heart Infusion is particularly recommended for the growth and 

 isolation of pathogenic microorganisms especially their primary isolation from 

 blood and other specimen material. 



The advantages of a medium with a low agar concentration and its influence 

 on the development of bacteria, particularly the anaerobes, has been described by 

 Kitchens.^ In a broth, to which 0.1 per cent agar has been added, there is a clear 

 upper zone well suited for aerobic growth; below this the flocculent agar develops 

 variable degrees of anaerobiosis. This condition makes the medium suitable for 

 the growth of either aerobic or anaerobic bacteria. Falk, Bucca, and Simmons^ 

 pointed out the advantages of the use of small quantities of agar (0.06 to 0.25 

 per cent) in the detection of contaminants in testing the sterility of biologicals. 

 They demonstrated that the growth of even common forms, such as the hay 



