DEHYDRATED CULTURE MEDIA 157 



BACTO 



TETRATHIONATE BROTH BASE (B104) 



DEHYDRATED 



Proteose Peptone, Difco 5 g. 



Bacto-Bile Salts 1 g. 



Calcium Carbonate 10 g. 



Sodium Thiosulfate 30 g. 



Bacto-Tetrathionate Broth Base is a selective liquid enrichment medium 

 employed in the isolation of Salmonella typhosa and other members of the 

 Salmonella (paratyphoid) group from feces, urine, water, sewage and infected 

 materials such as eggs and other foodstuffs. Its use is particularly indicated in 

 the early stages of enteric disorders, in determining the release of patients, and in 

 detecting carriers of typhoid and paratyphoid organisms. The use of Tetrathio- 

 nate Broth is specified in "Standard Methods for the Examination of Dairy 

 Products"^ for the isolation of bacteria from cheese. "Diagnostic Procedures and 

 Reagents"^ modify the formula by the addition of Brilliant Green to the enrich- 

 ment as used in the examination of specimens for Salmonella and Shigella. 



The credit for discovering the usefulness of a Tetrathionate Broth for enrich- 

 ing typhoid and the paratyphoid group is ascribed to Mueller^ who demonstrated 

 clearly that it inhibited or killed the coliform organisms and permitted typhoid 

 and the paratyphoids to grow almost unrestrictedly. Mueller obtained pure 

 cultures of typhoid by incubating mixtures containing few typhoid organisms and 

 infinite numbers of coli in his Tetrathionate Enrichment. 



Kauffmann,*'^ using a modified Mueller's broth claimed to have increased 

 his positive isolations of S. typhosa over 30 per cent and of other members 

 of the Salmonella group from 100 to 700 per cent over that possible by direct 

 streaking onto plate media. Schaeffer,^ using Tetrathionate Broth also demon- 

 strated the greater efficiency of Tetrathionate Enrichment by detecting four 

 times as many typhoid and paratyphoid positive fecal specimens as could be 

 found by direct plating. Further demonstrations of the usefulness of Tetra- 

 thionate Enrichment were made by Jones,^ Ruys^ and by Szper,^ who effected a 

 technique for its use in examining large volumes of water and sewage material. 

 Newman^*^ in a study of the detection of food poisoning attributable to dairy 

 products, used Tetrathionate Broth followed by streaking to Bismuth Sulfite Agar 

 and S S Agar for the isolation of Salmonella. 



The prepared broth is inoculated by adding 1-3 grams of stool, sewage, urine 

 or other infected material to 10 ml. of the medium and mixing with a swab, 

 glass rod or pipette to suspend the particulate matter. Many workers find it 

 advantageous to pass a loosely packed cotton plug down through the inoculated 

 broth to carry the coarser particles of fecal material to the bottom of the tube. 

 The inoculated medium is then incubated for 12-24 hours, and streaked out 

 upon Bacto-MacConkey Agar and Bacto-Bismuth Sulfite Agar. The inoculated 

 plates are incubated at 37°C. Examine the MacConkey Agar plates after 18-24 

 hours and the Bismuth Sulfite Agar plates at 24-48 hours for typical typhoid or 

 paratyphoid colonies. Confirm typical colonies on Bacto-Triple Sugar Iron Agar 

 or by other suitable means. In cases of suspected Salmonella infections other than 

 typhoid, some bacteriologists prefer to use Bacto-Brilliant Green Agar as a plating 

 medium after enrichment because of its selective reaction for these organismr. 



To rehydrate the medium, suspend 4.6 grams of Bacto-Tetrathionate Broth 

 Base in 100 ml. of distilled water, and heat to boiling. Cool below 45 °C. Add 

 2.0 ml. of iodine solution.* Shake to mix, and tube in 10 ml. quantities, in sterile 



*The iodine solution is prepared by dissolving 6 g. iodine crystals and 5 g. potassium iodide in 

 20 ml. of water. 



