Syphilis Testing

Name that Syphilis Stage! Case vignette/Key clues Painless chancre forms on glans penis (or vulva/cervix) and heals within 1 to 3 months Pathogenesis 3-week incubation during which spirochetes spread throughout the body Diagnosis Biopys/skin scraping viewed with Dark-field microscopy shows spirillar organisms

Primary Syphilis

What do Non-Treponemal tests do?

These tests determine the presence of an antibody that forms against Cardiolipin, a lipid material released from damaged cells. This antibody has sometimes been referred to as Reagin.

What organism causes Pinta?

Treponema carateum

What organism causes venereal syphilis?

Treponema pallidum subspecies pallidum

What organism causes "Yaws"?

Treponema pallidum subspecies pertenue

True/False: In general, nontreponemal tests are positive within 1 to 4 weeks after the appearance of the primary chancre

True

True/False: Testing of sera from patients in the secondary stage of syphilis is subject to false NEGatives because of the PROzone phenomenon (antibody excess)

True

Name that Syphilis Stage! Case vignette/Key clues Local or generalized rash lasting 1 to 3 months, can involve the palms and soles Common manifestations include mucocutaneous lesions and nontender lymphadenopathy. The fluid from skin lesions is highly infectious. The symptoms usually resolve spontaneously within a few weeks of onset (Mahon 915) Pathogenesis Develops 1 to 2 months after primary stage Diagnosis Serology: VDRL= POSitive (nonspecific) ; FTA-ABS (Specific)

secondary syphilis

What is the "Window period"?

time between exposure and POSitive test result

In qualitative complement-fixation tests prozone reactions are most likely to be responsible for a test reported as: A) False negative B) Doubtful C) Anticomplementary D) False positive

A

Interpret the following quantitative RPR test result: RPR titer: Weakly reactive: 1:8; Reactive: 1:8-1:64 A) Excess antibody; prozone effect B) Excess antigen; postzone effect C) Equivalence of antigen and antibody D) Impossible to interpret; testing error

A) Excess antibody; prozone effect This patient may be in the secondary stage of syphilis and is producing large amounts of antibody to T. pallidum sufficient to cause antibody excess in this test. The test became strongly reactive only after the antibody was diluted

Which test is most likely to be positive in the tertiary stage of syphilis? A) FTA-ABS B) RPR C) VDRL D) Wasserman complement fixation

A) FTA-ABS The FTA-ABS or one of the treponemal tests is more likely to be positive in the tertiary stage of syphilis. In some cases, systemic lesions have subsided by the tertiary stage and the nontreponemal tests become seronegative.

Which test is most likely to be positive in the tertiary stage of syphilis? A) FTA-ABS B) RPR C) VDRL D) Reagin screen test (RST)

A) FTA-ABS The FTA-ABS or one of the treponemal tests is more likely to be positive than a nontreponemal test in the tertiary stage of syphilis. Although the FTA-ABS is the most sensitive test for tertiary syphilis, it will be positive in both treated and untreated cases

Which laboratory test is most frequently used to diagnose and follow the course of therapy of a patient with secondary syphilis? A) Flocculation B) Precipitation C) Complement fixation D) Indirect Immunofluorescence

A) Flocculation Nontreponemal tests are used to screen for syphilis and monitor syphilis patients during therapy. These tests, the VDRL and RPR, are based on the principle of flocculation, created by the clumping of the fine cardiolipin particles used in the tests, after binding to patient's antibody. [Stevens 2017, p374]

The directions for a slide agglutination test instruct that after mixing the patient's serum and latex particles, the slide must be rotated for at least 2 minutes. What would happen if the slide were rotated for 10 minutes? A) Possible False Positive result B) Possible False Negative result C) No effect D) Depends on the amount of antibody present in the sample

A) Possible False Positive result Allowing the rxn to proceed beyond the recommended time may result in a false-positive reading. Drying on the slide may lead to a possible erroneous positive reading

Which syphilis test has high sensitivity in primary syphilis that decreases in later stages?

Antibody Capture ELISA

A 24-year-old man who had just recovered from infectious mononucleosis had evidence of a genital lesion. His RPR test was positive. What should the technologist do next? A) Report out as false positive B) Do a confirmatory treponemal test C) Do a VDRL D) Have the patient return in 2 weeks for a repeat test

B

Treponemal EIA tests for syphilis are characterized by all of the following EXCEPT: A) they are adaptable to automation B) they are useful in monitoring antibody titers in syphilis patients undergoing therapy C) subjectivity in reading is eliminated D) they can be used to distinguish between IgG and IgM antibodies

B

Which of the following is true of nontreponemal antibodies? A) They can be detected in all patients with primary syphilis B) These antibodies are directed against cardiolipin C) Nontreponemal tests remain positive after successful treatment D) The antibodies are only found in patients with syphilis

B

Which test is recommended for testing cerebrospinal fluid for detection of neurosyphilis? A) RPR B) VDRL C) FTA-ABS D) Enzyme immunoassay

B

A 22-year-old college student presents for the evaluation of a painless nonpruritic rash of 1 week in duration (Figure IV-158). Three months ago, he engaged in unprotected sexual intercourse. Two months ago, he noted a penile papule that evolved to a painless, clean-based, and indurated ulcer. He did not seek medical attention because the ulcer healed spontaneously. Subsequently, he developed the rash pictured in Figure IV-158. He complains of no other symptoms and has no stigmata of ocular or neurologic involvement. He reports no new medications and has no known drug allergies. He does not have HIV. What is the most appropriate antibiotic regimen? A) Azithromycin 1000 mg orally for one dose B) Benzathine penicillin G 2.4 mU IM for one dose C) Doxycycline 100 mg orally twice a day for 14 days D) Doxycycline 200 mg orally for one dose E) Penicillin G 18-24 mU/d IV for 14 days

B) Benzathine penicillin G 2.4 mU IM for one dose The image shows a diffuse maculopapular rash involving the trunk, palms, and soles. The patient's history of unprotected intercourse, a recent painless penile ulcer suspicious for a primary chancre, and the subsequent maculopapular rash involving the palms/soles is consistent with secondary syphilis. The lesion of primary syphilis is typically a painless, indurated papule that is typically located at the site of inoculation. In heterosexual men, it is typically located on the penis, although it can be variably found on the anus, rectum, lips, or oropharynx. The primary chancre typically heals spontaneously within 3-6 weeks, and because it is painless, some patients with primary syphilis do not initially seek medical attention. Secondary syphilis is sometimes described as the "great imitator" because its manifestations are protean. Common manifestations include mucocutaneous lesions and nontender lymphadenopathy but less commonly include meningitis, hepatitis, nephropathy, gastrointestinal involvement, arthritis, periostitis, or ocular findings. The preferred therapy for patients for primary, secondary, or early latent syphilis without neurologic or ocular involvement and without confirmed penicillin allergy is a single dose of intramuscular benzathine penicillin G. For patients with late latent syphilis (or latent syphilis of unknown duration), three doses of benzathine penicillin G over 3 weeks is preferred. Two weeks of intravenous penicillin G is recommended for treatment of neurosyphilis or ocular syphilis. However, absent signs or symptoms of nervous system involvement, an RPR ≥1:32, HIV infection, CD4 ≤350/μL, or suspected treatment failure, evaluation of the CSF is not mandatory. Tetracycline and doxycycline can be considered in patients with confirmed penicillin allergy but are not preferred in patients without penicillin allergy. Due to the increasing prevalence of macrolide resistance, azithromycin is not recommended. (Chap. 206)

Which serum antibody response usually characterizes the primary (early) stage of syphilis? A) Antibodies against syphilis are undetectable B) Detected 1-3 weeks after appearance of the primary chancre C) Detected in 50% of cases before the primary chancre disappears D) Detected within 2 weeks after infection

B) Detected 1-3 weeks after appearance of the primary chancre During the primary stage of syphilis, about 90% of patients develop antibodies between 1 and 3 weeks after the appearance of the primary chancre.

A biological false-positive reaction is LEAST likely with which test for syphilis? A) VDRL B) Flourescent T.pallidum antibody adsorption test (FTA-ABS) C) RPR D) All are equally likely to detect a false-positive result

B) Flourescent T.pallidum antibody adsorption test (FTA-ABS) The FTA-ABS test is more specific for T. pallidum than nontreponemal tests such as the VDRL and RPR and would be least likely to detect a biological false-positive result. The FTA-ABS test uses heat-inactivated serum that has benn absorbed withg the Reiter strain of T. pallidum to remove nonspecific antibodies. Nontreponemal tests have a biological false-positve rate of 1-10%, depending on the population tested. False-positive findings are caused commonly by infectious mononucleosis, SLE, viral hepatitis, and HIV infection.

What constitutes a positive reaction in an agglutination inhibition procedure? A) Agglutination B) Lack of agglutination C) Low-titered agglutination D) Depends on type of test

B) Lack of agglutination Agglutination inhibition is based upon an antigen-antibody reaction that occurs and prevents a particulate antigen ( the indicator reagent) from reacting with the antibody

All of the following are indications for CSF examination in adults infected with syphilis EXCEPT: A) HIV infection with CD4+ count ≤ 350/μL B) Maculopapular rash involving the palms and soles C) RPR titer ≥1:32 D) Sensorineural hearing loss E) Suspected treatment failure

B) Maculopapular rash involving the palms and soles (Chap. 206) Neurosyphilis can occur at any stage of syphilis (early or late). Although it is uncommon in the postantibiotic era, the incidence of neurosyphilis is higher in those co-infected with HIV and in those with high titer nontreponemal antibody tests. Indications for CSF fluid examination in adults with syphilis include signs or symptoms of nervous system involvement (e.g., meningitis, hearing loss, cranial nerve palsies, altered mental status, ophthalmic disease, ataxia), RPR or VDRL titer ≥1:32, active tertiary syphilis, or suspected treatment failure. In addition, patients with HIV, especially with CD4+ T-cell count ≤350/μL, should undergo CSF examination. Otherwise, CSF examination is not routinely recommended in primary or secondary syphilis absent neurologic signs or symptoms.

What substance is detected by the rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests for syphilis? A) Cardiolipin B) Reagin C) Specific antibody D) Treponema pallidum

B) Reagin Reagin is the name for a nontreponemal antibody that appears in the serum of syphilis-infected persons. Reagin reacts with cardiolipin, a lipid-rich extract of beef heart and other animal tissues

In the fluorescent treponemal antibody adsorption (FTA-ABS) Test, what is the purpose of absorption with Reiter treponemes? A) It removes reactivity with lupus antibody B) It prevents cross-reactivity with antibody to other T. pallidum species C) It prevents cross-reactivity with antibody to nonpathogenic treponemes D) All of the above

C

Presence of reagin can be demonstrated by: A) TPI B) FTA-ABS C) VDRL D) RPCF E) TPMB

C

The reverse screening algorithm for syphilis testing: A) is the CDC preferred algorithm B) is more labor intensive than the "traditional" method C) has a high number of false positives that must be resolved by doing a TP-PA test D) is more prone to transcription errors in reporting

C

Which of the following is a treponemal test for syphilis? A) VDRL B) RPR C) Microhemagglutinin test for T. pallidum (MHA-TP) D) all the others

C

Which of the following is true of treponemal tests for syphilis? A) They are usually negative in the primary stage B) Titers decrease with successful treatment C) In large-volume testing, they are often used as screening tests D) They are subject to a greater number of false positives than nontreponemal tests

C

Which syphilis test detects specific treponemal antibodies? A) RPR B) VDRL C) FTA-ABS D) Agglutination

C

What proportion of sexual contacts of persons with infectious syphilis become infected? A) 5-10% B) 10-33% C) 33-50% D) 50-67% E) 67-90%

C) 33-50% Early syphilis describes syphilis acquired within the first year and includes primary syphilis, secondary syphilis, and early latent syphilis. In contrast to late latent syphilis, patients with early syphilis are generally infectious, and their identification and treatment represent an important public health activity to interrupt the transmission of syphilis Nearly all syphilis is transmitted by sexual contact with infectious lesions. The mucocutaneous lesions of syphilis, especially the primary chancre and condyloma lata, are teeming with spirochetes and are highly infective. The infective dose is approximatlely 57 organisms, and the concentration of organism in a chancre is approximately 10^7 organisms per gram of tissue. One-third to one-half of sexucal contacts of persons with infectious syphilis become infected (Harrison's; Chapter 206)

Which specimen is the sample of choice to evaluate latent or tertiary syphilis? A) Serum sample B) Chancre fluid C) CSF D) Joint fluid

C) CSF latent syphilis usually begins after the second year of untreated infection. If neurosyphilis is present, cerebrospinal fluid serology will be positive and the CSF will display increased protein and pleocytosis characterisitic of central nervous system infection

What type of antigen is used in the rapid plasma reagin (RPR) card test? A) Live treponemal organisms B) Killed suspension of treponemal organisms C) Cardiolipin D) Tanned sheep cells

C) Cardiolipin Cardiolipin is extracted from animal tissues, such as COW hearts, and attached to carbon particles. In the presence of reagin, the particles will agglutinate.

A 65-year old woman is seen for evaluation of dementia. On physical examination, you note that her left pupil does not react well to light. However, when you test accommodation, she follows your finger with her eyes, and as you approach the bridge of her nose, you note the left pupil to constrict equally as well as the right one. The most important test to order at this point would be: A) Titer for Lyme disease B) B12 level C) RPR D) HIV E) Fasting glucose

C) RPR This is the typical Argyll Robertson pupil found in syphilis; the pupil accomodates, but it does not react. The RPR (rapid plasma reagin), a nontreponemal antibody test for syphilis, will be positive. (Braunwald, 15/e pp165,1048)

Darkfield microscopy is used to visualize: A) Borrelia recurrentis B) Mycoplasma pneumoniae C) Treponema pallidum D) Legionella pneumophila

C) Treponema pallidum Darkfield microscopy can be performed to visualize Treponema pallidum in genital or skin lesions. Darkfield examination allows for the visualization of T. pallidum's typical morphology and motility. [Mahon 2015, p535]

Advantages of direct fluorescent antibody testing to T. pallidum include all of the following EXCEPT: A) reading is less subjective than with dark-field testing B) monoclonal antibody makes the reaction very specific C) slides can be prepared for later reading D) careful specimen collection is less important than in dark-field testing

D

An RPR test done on a 19-year-old woman as part of a prenatal workup was negative but exhibited a rough appearance. What should the technologist do next? A) Report the result out as negative B) Do a VDRL test C) Send the sample for confirmatory testing D) Make serial dilutions and do a titer

D

False-POSitive nontreponemal tests for syphilis may occur because of which of the following? A) Infectious mononucleosis B) Systemic lupus C) Pregnancy D) All of the above

D

A 74-year old woman with mild cognitive impairment is screened for syphilis. She has no history of recent sexual activity or of prior exposure to syphilis. The prevalence of syphilis in her local population is low. Her rapid plasma reagin (RPR) is reactive with a titer of <1.2. Her fluorescent treponemal antibody adsorption test (FTA-ABS) is nonreactive. The reactive RPR is most likely: A) False negative because the nontreponemal test is negative B) False negative because the treponemal test is positive C) False positive because the nontreponemal test is negative D) False positive because the treponemal test is negative E) True positive because the nontreponemal test is positive.

D) False positive because the treponemal test is negative Serologic testing for syphilis includes nontreponemal and treponemal tests. The RPR is a widely used nontreponemal antibody test that is recommended for both screening and quantification of antibody to assess syphilis activity or treatment response. Nontreponemal tests (e.g. RPR or VDRL) detect antibodies directed against the cardiolipin-cholesterol-lecithin antigen complex, and false reactions may occur in patients with autoimmune conditions, injection drug use, other active infections, or pregnancy. False-positive results increase with increasing age, approaching 10% in patients >70 years old. Treponemal-specific serologic tests detect antibody absorbed (FTA-ABS) test, the T. pallidum particle agglutination test (TPPA), treponemal enzyme immunoassay (TP-EIA), and treponemal chemiluminescence immunoassays (TP-CIA). These tests are highly sensitive and likely remain positive after treatment. They do not distinguish current from prior infection. In early primary syphilis, treponemal tests may be more sensitive than nontreponemal tests; however, in this case, the nontreponemal test is positive and the treponemal test is negative. In a low-prevalence population, this is most consistent with a false-positive RPR. (Harrison's Principles of Internal Medicine; Chapter 206)

All of the following statements below regarding the use of agglutination reactions are true EXCEPT: A) Involve particulate antigens B) Reaction can usually be visually observed C) Carrier particle for antigen may be latex, RBCs, or yeast D) Inhibition of agglutination is a positive reaction

D) Inhibition of agglutination is a positive reaction Agglutination reactions are interpreted as positive when agglutination occurs. An assay in which agglutination is interpreted as negative is called an agglutination inhibition reaction.

Which of the following is the most sensitive test to detect congenital syphilis? A) VDRL B) RPR C) Microhemagglutinin test for T.pallidum (MHA-TP) D) PCR

D) PCR PCR will amplify a very small amount of DNA from T. pallidum and allow for detection of the organism in the infant. Antibody tests such as VDRL and RPR may detect maternal antibody only, not indicating if the infant has been infected

On a follow-up visit to her healthcare provider, a young woman was given the results of her FTA-ABS test. She had been symptomatic for a couple of months before this visit, with fever, swollen cervical lymph nodes, fatigue, and rash affecting the palms of her hands in the soles of her feet, but she was now feeling better. Earlier test strategies that one would expect the healthcare provider to have requested include all of the following EXCEPT: A) RPR B) TPHA C) VDRL D) RAST

D) RAST RAST is a method for testing for allergic reactions. The other tests are for syphilis antibody. [Rittenhouse-Olson 2018, p339] up

Fill in the Blank: Primary and Secondary syphilis can be diagnosed by demonstrating the presence of T. pallidum in exudates from skin lesions using ___________-______ microscopy.

Dark-field

What are the Treponemal Tests for syphilis?

FTA-ABS TP-PA EIA

Organism T. pallidum

Historical derivation pallidum, "pale" (refers to the fact these organisms are not stained with traditional dyes)

Organism Treponema

Historical derivation trepo, "turn"; nema "thread" (a turning thread; refers to the morphology of the bacteria)

The VDRL and ____ tests use cardiolipin antigen

RPR

Name that Syphilis Stage! Type of Rash skin; maculopapular; mucous membrane; condylomata lata Progression Generalized bronze rash involving the palms and soles Other symptoms Fever; lymphadenopathy, malaise, sore throat, splenomegaly, headache, arthralgias Pathogenesis Endotoxin Causative Agent Treponema pallidum Diagnosis Serology: VDRL (nonspecific), FTA-ABS (specific)

Secondary syphilis

Fill in the Blank: __________ is the most commonly acquired spirochete disease in the United States. It is typically spread through sexual transmission

Syphilis

Name that Syphilis Stage! Case vignette/Key clues Affects Central Nervous system, heart, and skin; characteristic lesion is gumma, may be single or multiple; most common in the liver, testes, and bone Pathogenesis Develops in one-third of untreated patients; Neurosyphilis: including meningovascular, tabes dorsalis, and general paresis; obliterative endarteritis of vasa vasorum of the aorta can lead to thoracic aneurysm Diagnosis Serology: ; FTA-ABS (Specific) = POSitive Non-Specific (Nontreponemal) tests may be NEGative

Tertiary Syphilis

What is a titer?

The highest dilution of a serum which still produces a visible reaction with a particular antigen

What is Cardiolipin?

The purified material from beef heart. It contains 4% phosphorous (but no nitrogen) and is soluble in alcohol(not in acetone). After addition of lecithin and cholesterol, _______ will flocculate (or fix complement) in the presence of syphilitic reagin

What are the NonTreponemal tests for syphilis?

VDRL (Venereal Disease Research Laboratory test) RPR (Rapid plasma reagin test) USR( unheated serum reagin test) TRUST (toluidine red unheated serum test)

What is a gumma?

a form of granuloma characteristic of tertiary syphils. Granulomas are organized clusters of WBCs and epithelial cells that are formed as a result of a Type IV Hypersensitivity reaction. This cell-mediated mechanism develops in response to chronic persistence of the antigen

What is the TP-PA (Treponema pallidum particle agglutination) test?

a microtiter agglutination test -Gelatin particles sensitized with T. pallidum antigens are mixed with dilutions of the patient's serum. -If antibodies are present, the particles agglutinate. -Treponemal specific test

What is flocculation?

a specific type of precipitiation that occurs over a narrow range of antigen concentrations. The antigen consists of very fine particles that clump together in a positive reaction. Nontreponemal tests are based on these reactions in which patient antibody complexes with the cardiolipin antigen