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13 Cards in this Set
- Front
- Back
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Syphilis
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Treponema pallidum
- Spirochetes - Treponemes - 6-15u - Corkscrew shaped, motile - Outer mb similar to gram negative bacteria - Very fragile cells -CANNOT grow in vitro Other pathogenic treponemes cause significant morbidity worldwide. - Primarily skin and mucous mb infections, not sexually transmitted |
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T. pallidum
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Transmitted by direct contact only
- Enters the body via skin and mucous mb through abrasions during sexual contact - Transmitted transplacentally to fetus during pregnancy Disease professes in stages - Travels via the lymphatic system to regional lymph nodes then throughout the body via the blood stream - Invasion of the CNA can occur during any stage of infection May become chronic without treatment |
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3 stages of disease if untreated: Primary stage
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PRIMARY
- Incubation period 10-90 days - Development of characteristic primary lesions "hard chancre" ---- At site of infection, painless, resolves spontaneously in 4-6 wks - Regional lymphadenopathy - Serologic tests may no be positive during early primary syphilis |
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Secondary stage
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- 2-8 wks after appearance of chancre, may persist for weeks or months
- May overlap with primary stage - Mucocutaneous lesions most common - Manifestations: Flulike symptoms, rash (75-100%), lymphadenopathy, mucous patches, alopecia - May or may not have CNS involvement - Serologic tests usually have highest titer during this stage |
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Latent syphilis and neurosyphilis
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Latent syphilis
- Host suppresses infection - no lesions - Positive serology Neurosyphilis - Organisms invade the CNS - May occur at any stage of infection - Can be asymptomatic - Manifestations: acute syphilitic meningitis, ocular involvement |
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Tertiary stage and congenital syphilis
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- AProx 30% of untreated patients progress to this stage 3-50 years after infection
- Rarely seen today because of availability of Antibiotis - Gumas: destructive granulomatous leions - Possible cardiac symptoms - Possible CNS involement - Usually fatal Congenital syphilis - Transplacental transmission, can occur during any trimester - Risk of transmission higher in primary and secondary stages of disease - May result in developmental disorders, deafness, and bone deformities |
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Dx
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- Clinical history, physical exam, and laboratory dx
- Identification of microorganisms in lesions by DARKFIELD microscopy DIRECT fluorescent Ab - T. pallidum (DFA -TP) - Serological testing for treponemal (Ag- specific) and non-treponemal Abs NON-TREPONEMAL: VDRL ,RPR TREPONEMAL: FTA - Abs and microhemagglutination T.pallidium (MHA-TP) |
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Direct observation: Darkfield microsopy
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- T.pallidum morphology and mobility
Advantage: Definitive immediate dx Disadvantage: REQUIRES specialized equipment and experienced microscopist, POSSIBLE confusion with other pathogenic and non-pathogenic spirochetes, NOT recommended for oral lesions, POSSIBILITY of false negative |
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Direct observation: DFA -TP
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Ids organism in direct lesion smear by immunoflourescence
Advantages: COMMERCIALLY available reagents, COMPARES favorably with dark field microscopy Disadvantages: LONGER turn around time |
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Non- Treponemal Tests
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- Can be qualitative and quantitative
- Positive non-treponemal tests should be followed up with confirmation using treponemal specific tests - Principle: measure Ab against cariolipin-lecitin-cholesterol Ag - Not specific for T. pal - Titers usually correlate with disease activity and results are reported quantitatively - RPR and VDRL - flocculation tests - RPR - most widely used on unheated serum: charcoal added allows for macroscopic reading - VDRL - can be used on CSF for Dx of neurosyphilis: read microscopically |
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Non-Treponemal test (Adv vs. Disadv)
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Adv:
- Rapid and inexpensive - Easy to perform and can be done in clinic or office - Quantitative - Used to follow response to therapy - Can be used to evaluate possible reinfection Disadv: - May be insensitive in certain stages - False positive rxn do occur - Przone effect may cause false negative (rare) |
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Treponemal methods
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- Measure Ab directed against T. pal Ag
- Tests are qualitative - Usually reactive for life - Used to confirm "pos" on non- treponemal tests FTA - ABS : killed suspension of organisms fixed to slide MHA- TP : microhemagglutination --- Agglutination by specific Abs in pts serum with sheep RBCs sensitized to T. pal Ag |
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Sensitivity of serological assays
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- Detection by serology related to both stage of disease and test method
- 90% of pts positive after 3 weeks - Secondary stage pts are serologically positive - Late syphilis- treponemal tests- positive NON- treponemal tests are non-reactive |
