Silver stains for the light and electron microscopic demonstration of spirochete changes in syphilis and AIDS

Abstract

Two new silver stains have been developed in our laboratories to stain, and possibly identify without culture or immunocytochemical staining, Gram(-) bacteria. The first is the PATS reaction which positively stains Gram(-) bacteria (Figs. 1, 2) including those like spirochetes which are difficult to culture. Another stain for Gram(-), as well as Gram(+), bacteria is a variation of the Gram stain. Ordinarily to stain Gram(+) bacteria, and not Gram(-) bacteria, the crystal violet stain is removed from Gram(-) microbes by rinsing with alcohol/acetone. If this rinse step is omitted, the crystal violet iodide remains attached to both the (+) and (-) microbes. It can then be rendered insoluble, electron opaque and conductive by treatment with silver methenamine solution under microwave irradiation. This procedure has been found especially useful in certain cases to demonstrate spirochetes; it appears to be a more effective silver stain than the PATS reaction forTreponema pallidum, the microbe causing syphilis.