11 Questions
What is the primary purpose of using treponemal serology tests in syphilis diagnosis?
To detect the presence of antibodies in patients
What is the significance of a negative result in a non-treponemal test following a positive treponemal test?
The patient has early or late/latent syphilis
What is the advantage of using PCR in early syphilis diagnosis?
It is a more specific method for detecting syphilis in lesion fluid
What is the trend in the use of treponemal serology tests in developed countries?
They are being used as a screening test due to improvements and cost reduction
What is the challenge in using syphilis serology in rural communities?
The lack of control of syphilis in rural communities
What is the primary reason why syphilis is not commonly diagnosed in its early stages?
The treponemes have a low protein surface membrane, making them poorly antigenic.
Which of the following is a characteristic of the tertiary stage of syphilis?
The settlement of the organism in connective tissue, such as the brain and bone.
What is the primary reason why non-treponemal tests are not used as a screening test for syphilis?
They have low sensitivity in early and late disease.
What is the primary consequence of congenital syphilis infection in the first trimester?
Microphthalmia and microcephaly.
What is the primary mechanism of action of the treponemal organism in connective tissue?
It hides in tissue, evading the immune response and causing damage over time.
What is the primary reason why biological false positives can occur in non-treponemal tests?
Other inflammatory disorders can release cross-reacting antigens.
Study Notes
Syphilis Overview
- Caused by spiral-shaped spirochaete Treponema pallidum
- Sensitive to penicillin and has never developed resistance
Stages of Syphilis
- Primary stage: soft, painless lesions (chancre) appear 3 weeks after exposure
- Secondary stage: rash appears 2-6 weeks later due to haematogenous spread
- Tertiary syphilis: symptoms appear 3-30 years later, affecting connective tissue, brain, bone, and vessel walls
Congenital Syphilis
- Infection in first trimester can result in microphthalmia, microcephaly, and bone and cartilage abnormalities
- Screening test used in antenatal checks
- Infection in late trimester results in less severe bone abnormalities and cognitive impairment
Pathogenesis
- Treponemes have low protein surface membrane, inducing a low immune response
- Early stages diagnosed based on tissue damage and antibodies
Serological Testing
- Non-treponemal tests (RPR and VDRL) used as screening tests, but have low sensitivity in early and late disease
- Non-treponemal tests can be used to monitor treatment response, reverting to negative after treatment
- Problems with biological false positives due to cross-reacting antigens in other inflammatory disorders
Treponemal Seroogy Tests
- Used to detect antibodies in patients using EIA
- Remain positive for many years despite treatment
- Improvements and lowering costs have made them suitable for screening tests in developed countries
Test your knowledge of syphilis, a bacterial infection caused by Treponema pallidum, and its primary, secondary, and tertiary stages. Learn about the symptoms, diagnosis, and treatment of this disease.
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