Syphilis Tests (RDR, VDLR)

Question 1

Reagin

Answer 1

antibody produced by infected patient against cardiolipin, an antigen of the spirochete

Question 2

RPR

Answer 2

Rapid Plasma Reagin

Question 3

VDRL

Answer 3

Venereal Disease Research Laboratory

Question 4

MHA-TP

Answer 4

Microhemagglutination-T. pallidum

Question 5

TP-PA

Answer 5

T. pallidum-particle agglutination

Question 6

FTA-ABS

Answer 6

fluorescent treponemal antibody absorption

Question 7

RPR principle.

Answer 7

Patient serum is mixed with antigen reagent. If reagin antibodies are present, they will flocculate with cardiolipin in the reagent. The charcoal particles co-flocculate with the reagent for visualization.

Question 8

Purpose of ingredients of RPR reagent:
- choline chloride
- lecithin
- cardiolipin
- charcoal

Answer 8

• choline chloride: inactivates complement
• lecithin: stabilizes reagent
• cardiolipin: acts as antigen
• charcoal: allows macroscopic reading of flocculation

Question 9

Describe 1st stage of syphilis.

Answer 9

Primary. Chancre nodule appears; painless ulcer; heals spontaneously.

Lasts 1-6 weeks.

25% progress to secondary.

Question 10

Determine which nontreponemal tests are more sensitive and/or specific during various stages of syphilis.

Answer 10

RPR
- 13-41% NR in primary stage.
- Almost all reactive by secondary stage.
- NR by tertiary stage.

VDRL
- Used for early detection of CNS involvement (secondary stage)
- Highly specific, lacks sensitivity (NR in 30-50% neurosyphilis)
- NR by tertiary stage.

Question 11

Specimen requirements for RPR and VDRL.

Answer 11

RPR: Serum or EDTA plasma if collected within 24 hours.

VDRL: CSF, centrifuged.

Question 12

Compare and contrast reagents for RPR and VDRL.

Answer 12

VDRL reagent lacks choline chloride (no complement in CSF) and charcoal (microscopic reading).

Question 13

5 causes for a biological false positive RPR result.

Answer 13

• SLE
• mononucleosis
• leprosy
• malaria
• other autoimmune disease

Question 14

Ag-Ab reactions that occur in FTA and MHA tests.

Answer 14

FTA: T. pallidum from rabbit testicles + patient serum. Incubate with anti-IgG conjugate with fluorescence.

MHA: Sheep RBCs coated with T. pallidum antigen + patient serum. Read for agglutination.

Question 15

Quality control requirements for RPR.

Answer 15

• Room temperature at 19-33° C
• Rotator speed at 100±2 RPMs
• Controls should show expected results.
• Antigen dispensing needle should dispense 60±2 drops/mL.
• New antigen lot numbers tested alongside current lot numbers before being put into use.

Question 16

Contrast clinical utility of non-treponemal vs treponemal tests.

Answer 16

Non-treponemal tests are screening tests. Prone to false positives. Positives should be confirmed with the treponemal confirmatory tests, which are specific to T. pallidum.

Question 17

WHO’s protocol for syphilis testing.

Answer 17

Traditional standard testing algorithms include screening with a nontreponemal test such as the RPR; a reactive specimen is then confirmed as a true positive with a treponemal test, such as the FTA-ABS. Confirmatory testing is necessary due to the potential for a false-positive screening test result. However, it is highly unlikely that any one patient will have false positive tests using both reagin and treponemal techniques; therefore, any person with a reactive nontreponemal test and a reactive treponemal test has presumptive syphilis.

Question 18

Describe 2nd stage of syphilis.

Answer 18

Secondary. Systemic. 6-8 weeks after initial chancre.

Generalized rash, lymphadenopathy, malaise, fever, pharyngitis; CNS involvement may occur.

30% of reported cases still have lesion.

Question 19

Describe 3rd stage of syphilis.

Answer 19

Latent. Rash resolves spontaneously. Clinical sx absent.

1/3 go on to develop tertiary form.

After 18th week, pregnant mothers transmit tremponeme to fetus.

Question 20

Describe 4th stage of syphilis.

Answer 20

Tertiary. Gummas form on bones, skin, SQ.

Occurs months or 10-30 years after secondary stage.

CV involvement; CNS involvement (neurosyphilis). Irreversible neuro effects.

Question 21

Quality control requirements for VDRL.

Answer 21

• Needle precision should be checked for delivery of 100±2 drops antigen per mL.
• Room temperature at 23-29° C.
• Rotator should be checked daily and set to 180±2 RPMs.
• Controls should show expected results.

Question 21

2 major spirochetal diseases

Answer 21

syphilis
lyme

Question 21

syphilis incubation

Answer 21

10-90 days

Question 21

syphilis CV involvement

Answer 21

aorta inflammation and destruction of aortic elastic tissue

Question 21

sx of neurosyphilis

Answer 21

• meningitis (in first 2 years of infection)
• degeneration of lower spinal cord
• general paresis
• chronic progressive dementia

Question 22

infant syphilis sx

Answer 22

clear or hemorrhagic rhinitis
rash on mouth, palms, soles of feet

Question 23

Immune response to syphilis

Answer 23

T cells and macrophages are protective
Antibody formed is not protective

Question 24

RPR false positive rate

Answer 24

1-2%

Question 25

may be better than VDRL, but not fully standardized

Answer 25

PCR

Question 26

5 treponemal tests

Answer 26

1. direct fluorescent antibody
2. FTA-ABS
3. MHA-TP
4. TP-PA
5. EIA

Question 27

Nontreponemal tests are more sensitive in ….. cases

Answer 27

congenital and neurosyphilis

Question 28

Treponemal tests are more sensitive in …. cases

Answer 28

latent and tertiary