TREPONEMA PALLADIUM

 

Treponema palladium 

✴ Morphology

• Thin delicate spirochete with tapering ends.

• 10 um long x 0.2-0.2 um wide.

• 10 regular spires – sharp & regular can not seen under the light microscope.

• India ink & phase contrast microscope.

• Fontana’s / levaditis method of staining. Cytoplasm enclosed by cell wall containing peptidoglycan outside that lipid – 3-4 endoflaglla between bothe.

✴ Culture –

• Not grow on artificial culture.

• Motile & virulent form for 10-12 day’s in complex media. Nichol’s strain (virulent) has been maintained in rabbit testes for several decades by serial testicular passage.

• Reiter strain – non pathogenic – group specific Ag. – thyoglycolate medium containing serum.

(anaerobical).

• Resistance –

• Inactivated by drying / heat (41-42°c) in 1 hr.

• Killed at 0-40c in 1-3 day’s. so storing blood for at least 4 day’s can be presented syphilis.

• Heat / fever therapy for syphilis.

✴ Antigenic Structure –

• Syphilis induces atleast three types of antibodies.

         1] Non – specific antigen –

• Regain appear’s in the blood of syphilitic patient.

• Regain Ag – hapton extracted from beef heart known as cardiolipin. Chemically diphosphatidyl glycerd.

• Ex – VDRL, wassermans, Kahn.

         2] Specific test –

 a] Group specific antigen –

 All pathogenic & non – pathogenic treponemas posses common group antigen.

 b] Species specific treponemal antigen –positive only with sera of patient infected with pathogenic treponemal.

✴Pathogenicity –

• Natural infection with T. pallidum occur’s only in human being’s.

• Experimentally monkey may be infected.

• Treponema enter’s through minute abrasion’s on skin / mucosa – clinical disease set’s after incubation period (10-90 day’s).

 3 clinical stages.

         1] Primary syphilis –

• Papules on genital area – ulcerating – heard chancre – covered by thick exudate very reach in spirochetes – regional lymphnodes are swollen, non tender & rubbery.

• Heals within 10 – 40 day’s.

        2] Secondary syphilis –

• After healing of primary lesion. Patient remains asymptomatic for 2-6 mint then secondary syphilis set in.

• Secondary lesion are due to widespread multiplication of treponemes. & their dissemination through blood.

 Lesion’s –Popular skin rashest, mucocutaneous patches in the oropharynx & condylomata at the mucocutaneous junction are characteristic lesion’s.

• Spirochetes are abundant in lesion.

       3] Tertiary syphilis –

• Contain few spirochetes diagnosis possible only by serology.

• Chronic granuloma (gummata), meningovascular manifestation.

      4] Congenital syphilis –

• It cross placenta. Infection in fetus usually occur’s from primary & secondary infection of mother.

✴Lab diagnosis –

• Consists of demonstration of spirochetes & antibodies in serum or CSF.

🔸Microscopy –

• Applicable in primary & secondary stage in case of congenital syphilis with superficial lesion’s.

• Collection – collected with care as lesion’s are highly infectious – cleaned with gauze –

margin’s gentely scraped so that the superficial epithelium is abraded.

• Gentle pressure is applied to the base of lesion & serum that exudated is collected preventing

admixture with blood.

• Examine under dark ground microscope.

• Direct fluorescent antibody test for T. pallidum is better.

🔸 Serological test’s –

 1] Test’s for antibodies reacting with cardiolipin antigen regain test – STS.

 2] Test for Ab’s reacting with group specific treponemal antigen.

 3] Test for Ab’s reacting to pathogenic treponemes.

∆ Non treponemal test’s –

• Cardiolipin antigen + lecithin + cholesterol.

• ex VDRL, RPR, Kahn test, Wassermann reaction.

• CFT

• All are flocculation test’s expect CFT.

• VDRL –

• Simple, rapid, slide flocculation test.

• Vineral disease research laboratory.

• VDRL Ag must be prepared fresh daily.

• RPR –

• Rapid plasma regain.

• Cardiolipin Ag + carbon particles.

• Done with unheated serum / plasma.

• Automated RPR test also available.

• Disadvantage of VDRL. (STS) –

• Non specific.

• Condition’s in which BFP reaction’s occur include.

• Leprosy, malaria, relapsing fever, infectious mononucleosis, hepatitis etc.

∆ Treponemal test-

• Group specific treponemal test –

For avoiding BFP reaction, test using cultivable treponemes as antigen were developed.

Ex – Reiter’s protein complement fixation test (RPCFT).

• Specific T palladium test’s –

Use of virulent Nichol's strain of T. palladium.

Ex – The fluorescent treponemal antibody (FTA) Treponema palladium haemagglutination test(TPHA).