Lesson 6
Theme: Methods of examination of patients with sexually transmitted diseases. Syphilis. Causative agent, transmission, clinical symptoms, immunity, classification. Primary syphilis of genital organs, chard chancre. Clinical and laboratory improvement of primary syphilis. Secondary syphilis, diagnosis, differential diagnosis, diagnosis acknowledgement.
Three Approaches to Diagnosis of STI
1. Clinical approach
2. Etiological approach
3. Syndromic approach
1. Syndromic Approach
u In this approach, diagnosis is based on the identification of syndromes, which are combinations of the symptoms the patient reports and the signs the health care provider observes
u The recommended treatments are effective for all the diseases that could cause the identified syndrome
Components of Syndromic Approach
· Classification by Syndrome:
· Classifying the main causal pathogens by the syndromes they produce
· Use of Algorithms:
· Using flowcharts to guide the management of a given syndrome
· Treatment and Counseling:
· Using often more than one treatment that addresses all the pathogens with potential to cause a given syndrome
· Treatment of Partners:
· Promoting treatment of sex partners.
STI Risk Assessment
Questions focus on
u Age
u Marital status
u Current or past STI symptoms
u Number of partners
u Nature of relationships
u The possibility of partners having other sexual partners
u Current symptoms in partners
Classification by Syndromes
u STIs are classified by syndrome
u Each syndrome is made up of a combination of symptoms and clinical signs identified upon examination
u The four main syndromes are:
Urethral discharge: men
Lower abdominal pain: women
Vaginal discharge: women
Genital ulcer: men or women
Syphilis
n Aka lues
n Contagious, sexually transmitted disease
n Spirochete Treponema pallidum
n Enters through skin or mucous membrane where primary manifestations are seen
Treponema pallidum
n Spiral spirochete that is mobile
n # of spirals varies from 4 to 14
n Length 5 to 20 microns
n Can be seen on fresh primary or secondary lesions by darkfield microscopy or fluorescent antibody techniques
n Motility has three movements
n Projection and rotation in the direction of the long axis
n Bending or twisting from side to side
n Pathogenic in apes, humans, and rabbits
Serologic Tests
n Reveal patients immune status not whether they are currently infected
n Use lipoidal antigens rather than T. pallidum or components of it; non-treponemal antigen tests
n RPR; rapid plasma reagin
n VDRL; Venereal Disease Research Laboratory
n Positive within 5 to 6 weeks after infection
n Strongly positive in secondary phase
n Strength of reaction is stated in dilutions
n May become negative with treatment or over decades
n To improve sensitivity and specificity tests using a specific treponemal antigen devised
n MHA-TP: microhemagglutination assay for T. pallidum
n FTA-ABS: fluorescent treponemal antibody absorption test
n All positive nontreponemal test results should be confirmed with a specific treponemal test
n Treponemal tests become positive early, useful in confirming primary syphilis
n Remain positive for life, useful in diagnosing late disease
n Treatment results in loss of positivity in 13-24% of patients.
WHO clinical classification of syphilis
The mode of transmission can be:
n Sexual, which is the most important mode of infection.
n Kissing the genitalia can produce extra- genital chancres on the lips, fingers and nipples.
n Sexual perversion ( homosexual and orogenital contacts ).
n Accidental inoculation.
n Through contaminated blood.
n Transplacental infection, from an infected mother to the fetus.
n During delivery as the baby passes through an infected canal.
Cutaneous Syphilis
n Chancre is usually the first cutaneous lesion
n 18 to 21 days after infection
n Round indurated papule with eroded surface that exudes a serous fluid
n Cartilage-like consistency
n Usually painless (Hunterian chancre is “classic” heals without scarring)
Primary syphilis-chancre
Primary syphilis-chancre
1. Inguinal adenopathy 1-2 weeks after chancre
2. Generally occur singly, may be multiple
3. Diameter mm to cm
4. Untreated, the chancre heals spontaneously in 1 to 4 months
5. Constitutional symptoms begin just as chancres disappear
6. Extragenital chancre: may be larger, frequently on lips, rarely tongue, tonsil, breast, finger, and anus.
Secondary Syphilis
n Skin manifestations in 80% called syphilids
n Symmetric, generalized, superficial, macular transient; later papular, pustular
n Early on face, shoulders, flanks, palms and soles, anal or genital areas
Secondary Syphilis Macular Eruptions
n Exanthematic erythema 6-8 weeks after chancre, extends rapidly, may last hours to months
n Round indistinct, slightly scaling ham-colored macules
n Pain, burning absent, pruritus may be present
n Generalized shotty adenopathy.
Secondary Syphilis Papular Eruptions
n Arise later than macular, raw-ham, round, 2-5mm or more in diameter, slightly raised, smooth or thick scale
n Face and flexures of arms and legs, trunk
n Palmar and plantar yellowish-red spots
n Ollendorf’s sign; papule tender to touch of a blunt probe
n Papulosquamous syphilids may produce a psoriasiform eruption
n Follicular or lichenoid syphilids appear as minute scale-capped papules
n Tend to be disseminated, but may be localized, asymmetrical, con figurate, hypertrophic, confluent.
Secondary Syphilis Papular Eruptions
n Lues Maligna; rare, severe ulcerations, pustules, or rupioid lesions, accompanied by severe constitutional symptoms.
n Condylomata lata; papular mass, weeping, gray 1-3cm, groin, anus (not vegetative like condylomata acuminata)
n Syphilitic alopecia; irregular, scalp has a moth-eaten appearance 5% of pts
Secondary Syphilis Mucous Membrane
n Present in 1/3 of secondary syphilis
n Most common is “syphilitic sore throat”
n Diffuse pharyngitis, hoarseness
n Tongue; patches of desquamation of papillae
n Ulcerations of tongue and lips in late stages
n Mucous patches are the most characteristic mucous membrane lesions; macerated, flat. Grayish, rounded erosions covered by a delicate, soggy membrane.
n Highly infectious, occur on tonsils, tongue, pharynx, gums, lips, and buccal areas, or on the genitalia.
Secondary Syphilis Systemic Involvement
n Lymphadenopathy common.
n Acute Glomerulonephritis, gastritis, proctitis, hepatitis, meningitis, SNHL, iritis, uveitis, optic neuritis, Bell’s palsy, pulmonary nodular infiltrates, osteomyelitis, polyarthritis.
Secondary Syphilis Ddx “Great Imitator”
n Pityriasis rosea
n Drug eruptions (pruitic)
n Lichen planus; Wickham’s striae, Koebner’s, pruitic
n Psoriasis; no adenopathy
n Sarcoidosis; need serology and silver staining of biopsy
n Infectious mononucleosis, false pos RPR
n Geographic tongue
n Aphthous stomatitis
n
Diagnosis of Syphilis
• Evaluation based on three factors:
– Clinical findings.
– Demonstration of spirochetes in clinical specimen.
– Present of antibodies in blood or cerebrospinal fluid.
• More than one test should be performed.
• No serological test can distinguish between other treponemal infections.
Laboratory Testing
• Direct examination of clinical specimen by dark-field microscopy or fluorescent antibody testing of sample.
• Non-specific or non-treponemal serological test to detect reagin, utilized as screening test only.
• Specific Treponemal antibody tests are used as a confirmatory test for a positive reagin test.
1. Nontreponemal Reagin Tests
• Non-specific or non-treponemal serological test to detect reagin, utilized as screening test only.
– Reagin is an antibody formed against cardiolipin.
– Found in sera of patients with syphilis as well as other diseases.
– This type of reagiot to be confused with same word originally used to describe IgE.
– Non treponemal tests become positive 1 to 4 weeks after appearance of primary chancre.
– in secondary stage may have false negative due to Prozone, in tertiary 25% are negative, after successful treatment will become nonreactive after 1 to 2 years.
• VDRL
• RPR
• USR-unheated serum reagin test
• RST-reagin screen test
• ELISA.
•
Laboratory – VDRL
• Flocculation test, antigen consists of very fine particles that precipitate out in the presence of reagin.
• Utilizes an antigen which consists of cardiolipin, cholesterol and lecithin.
– Antigen very technique dependent.
– Must be made up fresh daily.
• Serum must be heated to 56 C for 30 minutes to remove anti-complementary activity which may cause false positive, if serum is not tested within 4 hours must be reheated for 10 minutes.
• Calibrated syringe utilized to dispense antigen must deliver 60 drops/mL +/- 2drops.
Performing the test:
– 0.05 mL of serum added to circle on ceramic slide and spread.
– Add one calibrated drop of antigen to each circle.
– Rotate at 180 rpms for 4 minutes.
– Read microscopically at 100x and grade reaction if positive.
– Perform titer on positive samples, report out titer.
• Quality control:
– Run three levels of control: Non-reactive, weakly reactive and reactive.
– Glass syringe with 18g delivery needle must be checked daily to ensure delivery of 60 drops/mL.
– Rotator rpms must be checked to ensure 180 rpms.
– Room temperature must be 23-29 C.
• VDRL used primarily to screen cerebral spinal fluid.
• Each preparation of antigen suspension should first be examined by testing with known positive or negative serum controls.
• The antigen particles appear as short rod forms at magnification of about 100x. Aggregation of these particles into large or small clumps is interpreted as degrees of positivity
• Reactive on left, non-reactive on right.
Rapid Plasma Reagin Test – RPR
• General screening test, can be adapted to automation.
• CANNOT be performed on CSF.
• Antigen
– VDRL cardiolipin antigen is modified with choline chloride to make it more stable
– attached to charcoal particles to allow macroscopic reading
– antigen comes prepared and is very stable.
• Serum or plasma may be used for testing, serum is not heated.
• Test Procedure:
– Serum or plasma added to circle on card and spread.
– One drop of antigen from a needle capable of delivering 60 drops/mL is added.
– Rotate at 100 rpms/minute for 8 minutes.
– Results are read macroscopically.
• Daily quality control:
– 20 gauge needle checked for delivery of 60 drops/mL
– Rotator checked for 100 rpms/minute
– Room temperature must be 23-29 C.
– Three levels of control must be run and give appropriate results.
• RPR appears to be more sensitive than the VDRL.
Clumping of the carbon particles indicates the person’s serum contains nonspecific antilipid (reagin) antibodies.
RPR
• In the first test, the patient’s serum has caused flocculation of the carbon particles; indicative of active syphilis.
• After six months, however, the test is negative.
• This indicates that the antimicrobial therapy given at the time of the first test has been successful.
• Although the RPR test is a non-specific test, it is an excellent indicator of the success of therapy.
• Neg/Pos controls at top of slide, patient bottom right.
Specific Treponemal Tests
Performed to confirm a positive non-specific reagin test.
1. Treponema Pallidum Immobilization
2. Treponema pallidum hemagglutination
3. Fluorescent treponemal antibody absorption test
4. ELISA
1. Treponema Pallidum Immobilization – TPI
• An antibody present in the serum of a syphilitic patient, in the presence of complement, causes the immobilization of actively motile Treponema pallidum obtained from testes of a rabbit infected with syphilis.
• Cumbersome and expensive, no longer used in US.
2. Treponema pallidum hemagglutination (TPHA)
• Adapted to microtechniques (MHA-TP)
• Tanned sheep RBCs are coated with T. pallidum antigen from Nichol’s strain.
• Agglutination of the RBCs is a positive result.
• Based on the agglutination of colored gelatin particle carriers sensitized with T. pallidum antigen.
• Patient sera incubated with sensitized particles in microtiter wells and unsensitized gelatin particles in control wells.
• Patient sera containing specific antibodies will react only with the antigen to form a smooth mat of agglutinated particles.
• A compact button formed by the settling of the non-agglutinated particles in the microtiter wells containing sensitized particles indicates lack of specific antibody in patient sera (-).
• If agglutination is seen with both sensitized and unsensitized particles, nonspecific agglutination is indicated.
3. Positive FTA Test for Syphilis Viewed with a Flourescent Microscope
3. Fluorescent Treponemal Antibody Absorption Test (FTA-ABS)
• Diluted, heat inactivated serum added to Reiter’s strain of T. pallidum to remove cross reactivity due to other Treponemes.
• Slides are coated with Nichol’s strain of T. pallidum and add absorbed patient serum.
• Slides are washed, and incubated with antibody bound to a fluorescent tag.
• After washing the slides are examined for fluorescence.
• Requires experienced personnel to read.
• Highly sensitive and specific, but time consuming to perform.
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