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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

Internal Resources

DARKFIELD EXAM, SYPHILIS

Item Value
Approval req'd? yes, Microbiology Laboratory Medicine Resident
Available Stat? No
Test code DFE
Performed by? Microbiology (Bacteriology)
Sendout? no
Price range $$$
In House Availability AT SFGHMC, BY APPOINTMENT:

Monday - Friday 8:00 am - 5:00 pm

On weekdays, call and schedule with the Laboratory Medicine Resident in Microbiology, 206-5699
or pager (415) 443-1438.

Monday - Friday 5:00 pm - 10:00 pm
Saturday and Sunday 8:00 am - 10:00 pm

On PMs, weekends and holidays, schedule with the Laboratory Medicine Resident on call,
206-8590 or pager (415) 443-6969.


AT THE SAN FRANCISCO CITY CLINIC:

(487-5500), 356 - 7th Street, drop-in service is provided during the following hours:

Monday 8:00 am - 4:00 pm
Tuesday 1:00 pm - 6:00 pm
Wednesday 8:00 am - 4:00 pm
Thursday 1:00 pm - 4:00 pm
Friday 8:00 am - 4:00 pm
Saturday and Sunday SERVICE NOT AVAILABLE












Principle Motile treponemes may be present in a fresh lesion (chancre) of syphilis or a secondary syphilis skin lesion. Their characteristic motility and spiral shape can aid in the presumptive diagnosis of this infection before a serologic response can be detected. Darkfield microscopy is necessary because the organisms are not readily stained or visible in smears examined by conventional light microscopy.
Collection Instructions At SFGHMC, specimens must be collected by the Microbiology Laboratory Medicine Resident. Fluid is collected from the base of an unhealed chancre that has been gently cleansed with anti-bacterial-free saline. Persistent compression of edematous base of chancre will cause upwelling of fluid.

Secondary syphilis: Skin lesions are gently abraded with a #11 Bard-Parker blade with compression to collect fluid.
Normal range No Treponemes resembling T. pallidum seen
Synonyms Syphilis or Treponema Pallidum Studies, Darkfield;
Stability The specimen should be examined with a Darkfield Microscope within 15 minutes of collection
Additional information Note: One dose of penicillin renders darkfield search for Treponema pallidum valueless because it stops motility and alters the appearance of T. pallidum (it "unwinds" the characteristic spiral form).
References 1. Forbes BA, et al. Bailey and Scott's Diagnostic Microbiology, 11th Ed., Mosby, St. Louis MO, 2002.

2. Murray PR, et al. Manual of Clinical Microbiology, 9th Ed., ASM Press, Washington, DC, 2007.

3. Wentworth BB and Judson FN. Laboratory Methods for the Diagnosis of Sexually Transmitted Diseases, American Public Health Association, 1987.
CPT coding 87164
Last Updated 6/17/2011 1:19:42 PM
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