syphilis OSPE

Question 1

case

Answer 1

• 4-day history of painless penile lesions.
  -homosexual
• 2 partners in the last 6 months.
  Physical examination reveals nontender ulcers on the lateral aspect of the penile shaft and firm lymphadenopathy in the right inguinal region.

Question 2

specimen

Answer 2

-Exudate from primary and secondary lesions
-Biopsy
-blood for serology

Question 3

Collection

Answer 3

• The surface of the chancre is cleaned with saline
  -Gentle press at the base of the lesion and a drop of exudate is collected on a slide

Question 4

microscopy

Answer 4

Darkfield microscope: Slender, flexible, spirally coiled bacteria with pointed ends
* Corkscrew motility

Fluorescent microscope: distinct, sharply outlined, apple green fluorescent-coloured spirochete
-Direct Fluorescent Antibody Staining for T. pallidum (DFA-TP)
-Stained with fluorescent-labelled monoclonal antibody targeted against T. pallidum surface antigens

Silver Impregnation Staining: increase the
thickness of T. pallidum
Levaditi stain: stain tissue section

Question 5

primary diagnostic test for syphilis

Answer 5

Serology Test

Question 6

Standard test (Nontreponemal test)

Answer 6

• Used for screening patients
• Detect non-specific reagin antibody
• VDRL*: Formation of medium to large clumps of antigen-antibody complexes,can use CSF too

-RPR*:clumping seen, can use blood sample only

-Unheated Serum Reagin (USR),

-Toluidine Red Unheated Serum Test (TRUST)

Question 7

Treponemal/ Specific Test

Answer 7

❑TPHA (T. pallidum hemagglutination test) ❑TPPA (T. pallidum particle agglutination test)
❑MHA-TP (microhemagglutination T. pallidum)

Question 8

TPI (T. pallidum immobilization test)

Answer 8

❑Uses live actively motile T. pallidum
(Nichols strain)
❑Become immobilized after they combine with specific antibodies

Question 9

FTA-ABS (Fluorescent treponemal antibody absorption test)

Answer 9

❑Highly sensitive and specific in all the stages ❑Can also be used to detect CSF antibodies
❑IgM-FTA-ABS test
* A modification that detects only IgM antibodies
* Useful for congenital syphilis

Question 10

Molecular Tests

Answer 10

To amplify T. pallidum specific genes:
* Gene coding for 47- kDa surface antigen (lipoprotein)
* 39-kDa basic membrane protein

1)PCR
* Importance in the diagnosis of congenital and neurosyphilis

2)Multiplex PCR
* Simultaneous detection of common agents of genital ulcers
✓ T. pallidum
✓ H. ducreyi
✓ HSV