Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

Uses

To evaluate a lesion (chancre, mucous patch, condyloma lata, skin rash) for the presence of Treponema pallidum.

Materials

Compound microscope with dark-field condenser (dark-field microscope), glass microscope slide, coverslip, and physiologic saline.

Method

  1. From chancre or condyloma lata:

    1. Gently abrade the lesion with a dry gauze.

    2. Dab away any bleeding.

    3. Touch slide to exudative fluid in base of lesion.

    4. Overlay coverslip and view immediately under dark-field microscope using ×40 and ×100 objectives.

  2. From mucous patch:

    1. Touch slide to mucous patch.

    2. Overlay coverslip and view immediately under dark-field microscope using ×40 and ×100 objectives.

  3. From skin lesion:

    1. Gently scrape surface of skin lesion with edge of a number 15 scalpel blade.

    2. Dab away any bleeding.

    3. Touch slide to exudative fluid rising from skin lesion.

    4. Overlay coverslip and view immediately under dark-field microscope using ×40 and ×100 objectives.

FIGURE 25.15

Dark-Field Microscopy. Examined under a dark-field microscope at ×40 or ×100 power, spirochetes appear as motile, bright corkscrews against a black background. (Reproduced with permission, from Morse SA, Holmes KK, Ballard RC, Moreland AA (eds). Atlas of Sexually Transmitted Diseases and AIDS. 4th ed. Saunders Elsevier; 2010. Copyright © 2010 Elsevier, Ltd.)

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.