Petrignani environment

Petrignani environment (G. Petragnani) - Wednesday, proposed for isolation of mycobacteria from different allocations (sputum, stool, and others). To inhibit the growth of other microbes in the environment is contained bactericidal dye malachite green. Petrignani environment consists of eggs, milk, potato starch (flour), peptone or, better, asparagine.
Method of preparation: in a sterile liter flask with glass beads pour 150 ml of fresh cow's milk neutral; add 6 g potato starch, 1 g peptone (or 1.25 g asparagina) and finely sliced potatoes the size of a chicken egg. Then the flask is placed in a water bath and with constant agitation boil 10 minutes to complete uniform thick content. After being cooled to 50-60 degrees flask add sterile 4 fresh eggs and one egg yolk, 12 ml anhydrous sterile glycerol and 6 ml of 2% aqueous solution malachite green. All mix, sterile filtered through a double layer of gauze, sterile poured in tubes and roll in a slanted position in the apparatus Koch (30 minutes at 85 degrees). In the following 2 days of P.F. in the same machine warm up for 15 minutes at a 75-degree sterility. Ready environment is light green.
The growth of P.F. colonies of bacteria different types has characteristic differences, obnarujivaesh in 2-4 weeks after sowing. P.F. can be stored in the refrigerator at 4-8°, but it is better to apply it fresh as possible. There are a large number of modifications P.F. Cm. also Differential diagnostic environment. The nutrient medium.