LABORATORY Flashcards
(54 cards)
Specimens: SYPHILIS
• Tissue fluid expressed from [?] and [?] for microscopy
• [?] or [?] for serologic testing
• A small section of [?] for testing congenital syphilis
ulcers and lesions
Blood (serum) or CSF
• For detection of T. pallidum in primary and secondary lesions
It will show brightly lit motile, long, coiled or spiral treponemes (in white arrows) against a dark backdrop
Darkfield microscopy for
T. pallidum
• For detection of T. pallidum in primary and secondary lesions
It visualizes specimens on slides with fluorescein-labeled antitreponemal
antibodies by fluorescence microscopy
Direct fluorescent antibody test
for T. pallidum (DFA-TP)
• For detection of T. pallidum in primary and secondary lesions
(Levaditi’s, Warthin-Starry, Dieterle,
or Fontana-Tribondeau method)
Silver-impregnation technique
T. pallidum are so thin and they do not stain well with a\
aniline dyes
T. pallidum are NOT cultured on
artificial media
used to confirm evidence of secondary and tertiary syphilis, and the only means to diagnose latent syphilis
Serological Test for syphilis (STS)
Standard these tests include the following:
i. VDRL (for Venereal Disease Research Laboratory)
ii. Rapid plasma reagin (RPR)
iii. Unheated serum reagin (USR)
iv. Toluidine red unheated serum (TRUST)
Nontreponemal tests
The nontreponemal tests detect serum antibodies, known as reagin, released from cells damaged by treponemes. They are based on the reaction of reagin with a phospholipid antigen, [?], which is usually extracted from beef heart to produce a visible clumping, or flocculation, within the serum.
cardiolipin
card showing nonreactive, weakly reactive, and strongly reactive serum samples (wells 1 to 3) with their respective agglutination patterns
Rapid plasmin reagin test
As a consequence, they are not specific for Treponema but have been used traditionally to screen for disease. However, they are useful only after the body has a sufficient amount of time to generate a detectable amount of reagin. Antibodies detected by these tests generally develop in 4-5 weeks of the initial infection (or, 1-4 weeks after the appearance of the primary chancre). There are many other diseases that result in [?] and false positives are common.
anti-cardiolipin antibodies
Nontreponemal tests are also used to monitor the course of the disease after
treatment. Positive tests revert to negative, often in [?] months In treated patients, and generally 3 years after.
6-18 mons
These tests include the following:
i. T pallidum-particle agglutination (TP-PA)
ii. T pallidum hemagglutination (TPHA)
iii. Microhemagglutination T pallidum (MHA-TP)
iv. Fluorescent treponemal antibody absorbed test (FTA-ABS)
v. Enzyme immunoassay (EIA)
Treponemal testsv
Treponemal tests are based on detecting the presence of [?] against T. pallidum surface antigens.
“specific” serum antibodies
They have traditionally been used to confirm a [?], or to confirm infection in the face of a negative nontreponemal test in late or latent disease stages. Treponemal-specific antibody develops 2-3 weeks of initial infection.
positive nontreponemal screening test
However, they cannot be used to monitor the response to therapy, or to detect relapse or reinfection in previously treated patients. [?] remain reactive for years, regardless of treatment status.
Antitreponemal antibodies
are available in some reference laboratories. It may be useful in the diagnosis of primary infection, when serologic tests are often still negative, and has been advocated for the diagnosis of neurosyphilis, particularly in AIDS patients, although some studies have not demonstrated advantages over currently used methods.
Molecular method (Nucleic Acid Amplification Test) = Polymerase Chain Reaction (PCR)
• Blood, obtained during febrile episode, for direct microscopy
• Blood (plasma), spinal fluid, synovial fluid or macerated tissue biopsy for
culture
RELAPSING FEVER (Borrelia recurrentis)
Microscopic examination of peripheral blood samples obtained during febrile episodes
RELAPSING FEVER (Borrelia recurrentis)
Borrelia species are stained well by aniline dyes, and reveal large, loosely coiled spirochetes.
Wright’s or Giemsa’s stains of fixed thin and thick blood smears
In blood mixed with equal parts of sterile, nonbacteriostatic saline, Borrelia
species move rapidly, often pushing the red blood cells around.
Dark- or brightfield microscopy of wet preparations of peripheral blood
The organism is extremely difficult to culture
Borrelia recurrentis
Borrelia recurrentis uses [?] medium, a nutritionally-rich fluid medium containing blood, serum, or tissue; incubate at 30°C to 34°C for up to 12 weeks under microaerophilic conditions.
Modified Kelly’s
are performed weekly from the lower portion of the broth to fresh media, and the cultures are examined by dark-field microscopy or by fluorescence microscopy after staining with acridine orange for the presence of spirochetes
Blind subcultures (0.1 mL)
