A simplified method has been worked out in which one can preserve the treponema pallida for demonstration purposes even as long as 3 months after a darkfield examination has been done. When a primary or secondary lesion of syphilis has been scraped and the spirochetes demonstrated under the darkfield microscope one can then take another sample or 2 of the positive serum for darkfield examination to be shown at some later date. The following technique is carried out.
Place a drop of Crown immersion oil on a clean glass slide.
With a cover glass pick up a drop of serum from the lesion.
Invert the cover glass containing the serum onto the glass slide containing the drop of Crown immersion oil. This will incorporate the serum with the oil.
The specimens can be examined immediately under the darkfield microscope or they can be placed in the ordinary kitchen refrigerator (not
COHEN MM. A Simple and Rapid Method for Preserving the Treponema Pallidum for Demonstration Purposes. Arch Dermatol. 1961;84(4):672. doi:10.1001/archderm.1961.01580160136030
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