Silver Impregnation Techniques to Identify Spirochetes and Other Bacteria

Abstract

The diagnosis of syphilis, some gastric ulcers, Lyme disease, Legionnaire's disease, cat scratch fever, and others are dependent on the accurate identification of the causative bacteria. Many of these are usually identified with silver impregnation techniques because they are not demonstrated satisfactorily by the Gram stain. Morphologic differences are slight among the treponemes. Certain other types of bacteria must be handled carefully and their exact measurements known in order to make positive identification. A modification of the Steiner method for spirochetes, which also can be used for other bacteria, is presented. This method uses 0.1% uranyl nitrate. Sensitization is carried out with 0.1% silver nitrate. Sections are exposed to a physical developer with both low levels of silver nitrate and hydroquinone, which provides clear delineation of bacteria with minimum background and connective tissue staining. Elimination of calcium and formalin pigment is essential when few microorganisms are present; however, Legionella pneunophila is affected by this pretreatment. For proper demonstration use 2 slides; one with pretreatment and the other without for all types of bacteria other than treponemes. This procedure, without pretreatment, takes approximately 25 min. (The J Histotechnol 19:203, 1996)

Keywords:

• Helicobacter pylori
• Legionella pneumophila
• silver nitrate
• spirochetes
• uranyl nitrate