ORAL REVALIDA 2 Flashcards
What is the causative agent of syphilis?
Treponema pallidum subsp. pallidum, a spirochete.
How is syphilis transmitted?
Through direct contact (e.g., sexual contact) or placental transmission (congenital syphilis).
What happens during the incubation period of syphilis?
The bacteria spread through the bloodstream to organs. This stage lasts 10 days to 10 weeks and has no symptoms.
What is the hallmark symptom of primary syphilis?
A painless, non-bleeding ulcer called a chancre, appearing 2-3 weeks post-infection.
When do antibodies appear in primary syphilis?
1-4 weeks after the chancre appears.
How is T. pallidum detected in primary syphilis?
Darkfield microscopy of the lesion.
What are the symptoms of secondary syphilis?
Skin rash, fever, malaise, pharyngitis, weight loss, joint pain, and lymphadenopathy.
What is condyloma lata?
Large, plate, flat topped papules that occur in warm, moist areas (e.g., perianal region) and are highly infectious.
Are serologic tests positive in secondary syphilis?
Yes, both nontreponemal and treponemal tests are positive.
What characterizes latent syphilis?
a stage of syphilis with no signs or symptoms but with positive serologic tests (treponemal & nontreponemal)
What is the difference between early and late latency?
Early latency: 1 out of 4 individuals relapse into secondary syphilis.
Late latency: No relapse; patient is resistant to reinfection.
When does tertiary syphilis occur?
2 to 40 years after initial infection.
What are gummas in tertiary syphilis?
- Destructive, granulomatous lesions that can be single or multiple caused by hypersensitivity to treponemal antigens.
- They heal slowly, leaving an atrophic scar with hyperpigmented borders. They are treatment-responsive.
What cardiovascular complications can occur in tertiary syphilis?
Syphilitic aortitis, aortic valve insufficiency, and thoracic aneurysm.
What are the neurological effects of neurosyphilis?
Blindness, senility, and other neurological impairments.
Can Treponema pallidum cross the placenta?
Yes, it can infect the fetus at any stage of maternal syphilis.
What are the possible fetal outcomes?
Late abortion, stillbirth, neonatal death, neonatal disease, or latent infection.
Which maternal syphilis stages have the worst fetal outcomes?
Primary and secondary syphilis.
How can congenital syphilis be prevented?
Maternal treatment within the first 4 months of pregnancy.
What are the clinical signs of congenital syphilis?
• Maculopapular rash with desquamation (mouth, palms, soles)
• Hemolytic anemia, jaundice, hepatosplenomegaly
• Abnormal cartilage and bone development
• Mental retardation
How is syphilis diagnosed?
Signs and symptoms, detection of spirochetes in
lesion, and positive syphilis serology
What samples are used for direct detection of T. pallidum?
CSF, umbilical cord, skin, or mucous membrane lesions.
What microscopy techniques are used to detect T. pallidum?
• Darkfield microscopy
• Silver stain
• Direct Fluorescent Antibody (DFA-TP) test (fluorescent-labeled antibody detection).
What antibodies are produced in Treponema pallidum infection?
Nonspecific antibody, reagin, and specific treponemal antibodies.
Why are nontreponemal tests only used for screening?
They detect reagin, which can cross-react with antigens from SLE, autoimmune diseases, pregnancy, and chronic infections (e.g., hepatitis), leading to false positives.
What are examples of nontreponemal antigen tests?
VDRL, USR, and RPR.
Why must nontreponemal test results be confirmed?
They have a high false positive rate (30%), so treponemal tests confirm the diagnosis.
What are examples of treponemal antigen tests?
FTA-ABS, TP-PA, and microhemagglutination tests
What does the VDRL test detect?
Reagin antibodies against cardiolipin, cholesterol, and lecithin
How are VDRL test results interpreted?
Microscopic flocculation, reported as NR (nonreactive), WR (weak reactive), or R (reactive).
When does VDRL become positive?
1-3 weeks after the chancre appears.
What is the primary use of the VDRL test today?
CSF testing for neurosyphilis (the only serologic test approved for CSF).
How does the USR test differ from VDRL?
a modified VDRL test wherein Choline-chloride EDTA is added, allowing testing of unheated serum.
What is the principle of the RPR test?
- Macroscopic flocculation using VDRL antigen with charcoal particles for visualization.
- The antigen is not attached to the charcoal as in latex agglutination assays. The
charcoal is trapped in the flocculation reaction,
which allows the reaction to be seen macroscopically.
How is the RPR test reported?
As qualitative (reactive/nonreactive) or semiquantitative (antibody titers)
What is the principle of the TP-PA test?
Treponemal antigen is combined with liposomes. If antibodies are present, a mat of agglutination forms in wells of a microtiter plate.
What type of test is FTA-ABS?
An indirect antibody test.
What antigen does the FTA-ABS test use?
The Nichol’s strain of T. pallidum.
How are nonpathogenic treponemal antibodies removed in FTA-ABS?
By absorbing the serum with the Reiter’s strain of nonpathogenic treponeme
How are FTA-ABS results determined?
Fluorescence intensity, graded 1+ to 4+.
FTA-ABS test process
- Nichol’s strain of T. pallidum subsp. pallidum is affixed into wells of microscope slides.
2.Patient serum is heat inactivated. Nontreponemal antibody is absorbed from
patient serum with a sorbent of Reiter’s strain of
nonpathogenic treponeme.
- Sera are placed in the wells of the microscope
slide. - FITC-labeled antihuman antibody is added.
- Fluorescent reactions are graded 1 to 4+
what is abbott’s syphilis test used for
lateral flow immunochromatographic assay for qualitative detection of T. pallidum antibodies (IgG, IgM, IgA)
principle of rapid/abbott syphilis test
The recombinant Treponema pallidum antigens (17, 15 kDa) conjugated with colloidal gold
patient specimen and specimen diluent moves along the membrane chromatographically
to the test region T and forms a visible line
how many drops of serum, and how much time till you read the results in syphilis rapid test
4 drops of serum, 5-20 mins
reagents and materials used for abbott syphilis test
- test device ( coated w/ t. pallidum antigens)
- assay diluent
- capillary pipette
- sample
