DRIGALSKOGO-KONRADI WEDNESDAY (To. W. Drigalski, is mute. bacteriologist, 1871 — 1952; H. Conradi, is mute. bacteriologist, sort. in 1876) — the dense differential and diagnostic environment with lactose, indicators litmus and a crystal violet. It is offered by Drigalsky and Konradi in 1902 for differentiation of pathogenic salmonellas and shigellas with colibacillus. On D. — To. the pages of bacterial clump splitting lactose (colibacillus) and Wednesday around them are painted in red color due to formation of acid products and the discoloration of the indicator caused by them. Bacterial clumps, not splitting lactose (salmonellas, shigellas), keep blue-violet color of the environment. The crystal violet is added on Wednesday for suppression of growth of the accompanying bacteria.
According to an original copy-book for preparation of Wednesday 1500 of mincemeat fill in 2 l of water for the night. Forcemeat is wrung out, and liquid is boiled 1 hour, filtered and brought to initial volume; add 20 g of peptone, 20 g of nutrose (casein-sodium), 10 g of NaCl, boil 1 hour, filter, add 60 g of the crushed agar, autoclave, establish alkalescent reaction, filter in a hot state and again boil 30 min. At the same time 260 ml of a litmus tincture boil 10 min., add 30 g of lactose and again boil 15 min. Mix is added to 2 l of the prepared hot agar. Reaction of the environment is led up by 10% hot sterile solution of soda to alkalescent and over it add And ml of solution of soda. Add 20 ml of 0,1% of sterile hot solution of a crystal violet. On the Wednesday used for allocation of dysenteric bacteria, the crystal violet is not added. The received environment without additional sterilization is spilled on Petri dishes or in flasks before the use.
There are numerous modifications of the environment concerning technology of preparation of a nutritious basis.
See also Differential and diagnostic environments .
Bibliography: Drigalski u. Conradi H. t)ber ein Verfahren zum Nachweis der Ty-phusbacillen, Z. Hyg. Infekt. - Kr., Bd 39, S. 283,1902. Bibliogr.
S. S. Belokrysenko.