Читать книгу Practical Guide to Diagnostic Parasitology - Lynne Shore Garcia - Страница 83

Schaudinn’s fluid (which contains mercuric chloride) was one of the original stool fixatives and is used with fresh stool specimens or samples from the intestinal mucosal surface. Many laboratories that receive specimens from in-house patients (which have fewer problems with delivery times) often select this approach. Permanent stained smears are then prepared from fixed material. A concentration technique using Schaudinn’s fluid-preserved material is also available but is not widely used. Due to the difficulties (sources and cost) related to mercury disposal, this fixative is being phased out by most laboratories. Although mercury substitutes are available, the overall protozoan morphology does not tend to be as precise as that seen when mercury-based fixatives are used.

Mercuric chloride, saturated aqueous solution

Mercuric chloride (HgCl₂). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 g Distilled water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,000 ml

Use a beaker as a water bath; boil (use a hood if available) until the mercuric chloride is dissolved; let stand several hours until crystals form.

Schaudinn’s fixative (stock solution)

Mercuric chloride, saturated aqueous solution . . . . . . . . . 600 ml

Ethyl alcohol, 95% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 ml

Immediately before use, add glacial acetic acid, 5 ml/100 ml of stock solution.

Summary: Schaudinn’s Fluid