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Treponema pallidum
Treponema pallidum is a spirochete bacterium that causes syphilis. It is thin and delicate, about 10 micrometers in length, and actively motile. T. pallidum cannot be grown in culture but can be seen microscopically using dark-field illumination or silver staining. Syphilis has stages including primary, secondary, latent, and tertiary, and can involve multiple organs if untreated. Diagnosis involves microscopic examination of samples or serological tests to detect antibodies. Penicillin is the treatment of choice.
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Treponema pallidum
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- 2. INTRODUCTION • Spirochaetes areelongated, motile, flexible bacteria twisted spirally along the long axis. (Speira – meaning coil and chaite – meaning hair). • Structurally more complex than other bacteria. Characteristic feature is the presence of varying numbers of endoflagella, which are polar flagella wound along the helical protoplasmic cylinder, and situated between the outer membrane and cell wall. • Endoflagella are responsible for motility.
- 3. Order-Spirochetales • Family- (a)Spirochetaceae;(Genera Treponema & Borrelia) (b) Leptospiraceae(Genera Leptospira ) • Human pathogens are found in the genera – Treponema – Borrelia – Leptospira. • Genus Spirochaeta are saprophytes found in water and sewage
- 4. TREPONEMA • Treponemes (trepos,meaning to turn, and nema, meaning thread) are relatively short slender spirochetes with fine spirals and pointed or rounded ends. • Some of them are pathogenic, while others occur as commensals in the mouth, intestines, and genitalia. • Pathogenic treponemes are NOT CULTIVIABLE on ordinary media though commensals can be grown in artificial media.
- 5. TREPONEMA • Treponemes causefollowing diseases in humans : – Venereal syphilis caused by T. pallidum. – Endemic syphilis caused by T. pallidum (T. endemicum) – Yaws caused by T. pertenue. – Pinta caused by T. carateum. • They are almost identical in their morphology, antigenic structure and other features but show differences in their clinical features and natural history of the diseases they produce.
- 6. Treponema pallidum • Treponemapallidum, the causative agent of syphilis, was discovered in the chancres and inguinal lymph nodes of syphilitic patients. The name pallidum refers to its pale staining.
- 7. Treponema pallidum • Morphology:-A thin delicate spirochete with tapering ends, about 10µm long (range 4- 14µm) and 0.1-0.2µm wide. It has about ten regular spirals, which are sharp and angular, at intervals of about 1µm. • It is actively motile, exhibiting rotation around the long axis, backward and forward movement, and flexion of the whole body.(Corkscrew motility)
- 8. Microscopy • In wetfilms cannot be seen under light microscopy but can be made out by negative staining with India ink. • Motility and morphology can be seen under Dark Ground Illumination(DGI) & Phase Contrast Microscope. • Gram negative bacilli. Does not take ordinary bacterial stains. Prolonged Giemsa staining – stains light rose red. • Stained by silver impregation methods – Fontana’s method for films/smears – Levaditi’s method for tissue sections.
- 9. Special Staining MethodsFontana’s and Levaditi’s Methods. 9
- 10. Cultural characteristics • T.pallidum do not grow in artificial culture media. • Maintained in motile and virulent form for 10-12 days in complex media under anaerobic conditions. • Serial testicular passage in rabbits maintain virulent T.pallidum for many decades eg. Nichol’s strain. • Reiter strain (T.phagedenix), nonpathogenic treponeme, grows well in thioglycollate medium.
- 11. Resistance • T.pallidum isvery a delicate organism. • Readily inactivated by drying or heat(41-42oC in 1hr). • Killed in 1-3 days at 0-4oC. Transfusion syphilis prevented by storing blood for atleast four days in the fridge before transfusion. • Remains viable for 10-15 years at -70oC in 10% glycerol, or in liquid nitrogen(-130oC). • Inactivated by contact with oxygen, distilled water, soap, common antiseptic agents and antibiotics.
- 12. 12 Pathology • • Penetration: – T.pallidum enters the body via skin and mucous membranes through abrasions during sexual contact – Also transmitted transplacentally – Infective dose is small (60 treponemes being capable of infection). • Dissemination: – Travels via the lymphatic system to regional lymph nodes and then throughout the body via the blood stream – Invasion of the CNS can occur during any stage of syphilis
- 13. STAGES OF SYPHILIS 1.Primary 2. Secondary 3. Latent • • Early latent Late latent 1. Late or tertiary • May involve any organ, but main parts are: – Neurosyphilis – Cardiovascular syphilis – Late benign (gumma)
- 14. Clinical significance • Thefirst symptom of primary syphilis is a hard, painless genital or oral ulcer (chancre) that develops at the site of inoculation. • The average period between infection and the appearance of the chancre is about 3 weeks but varies with the number of infecting organisms. • This primary lesion heals spontaneously, but the organism continues to spread throughout the body via the lymph and blood. • An asymptomatic period ensues, lasting as long as 24 weeks, followed by the secondary stage.
- 15. Clinical significance • TheSecondary stage is characterized by the appearance of a red, maculopapular rash on almost any part of the body, including the palms of the hands and soles of the feet. • Pale, moist, flat papules seen primarily in the anogenital region, armpits, and mouth. • Both primary and secondary lesions teem with T. pallidum and are extremely infectious. • The secondary stage may be accompanied by multiorgan involvement, causing hepatitis, meningitis, nephritis.
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- 17. Tertiary stage • Uponhealing of the secondary lesions, the disease enters a latent period that can last for many years. • In approximately 40 percent of infected individuals, the disease progresses to a tertiary stage. • Characterized by degeneration of the nervous system; cardiovascular lesions and granulomatous lesions (gummas) in the liver, skin, and bones.
- 18. Congenital Syphilis • Congenitalsyphilis usually occurs following vertical transmission of T. pallidum from the infected mother to the fetus in utero, but neonates may also be infected during passage through the infected birth canal at delivery. 18
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- 20. • Lab aidessential for – Diagnosis of disease & Assessing cure after treatment • Lab diagnosis consists of demonstration of – Spirochetes under the microscope (microscopy) – Antibodies in serum or CSF (serological test) • Microscopy – done in primary and secondary stages & congenital syphilis – Wet films examined under DGI – Direct fluorescent antibody test (DFA-TP) • Serological tests – mainstay of lab diagnosis. Classified as follows:- – Tests for Ab to cardiolipin Ag – Tests for Ab to group specific (treponemal Ag) – Tests for Ab to species specific Ag (T.pallidum)
- 21. Sample collection Fordirect examination, exudates from lesions of primary, secondary and early congenital syphilis are the most useful. Clear, serous fluid free of erythrocytes, tissue debris. Serum is the specimen of choice for both nontreponemal and treponemal serological tests. Cerebrospinal fluid (CSF) testing is indicated in congenital and tertiary syphilis and when neurological symptoms are present.
- 22. Microscopy Can beseen with : Negative staining with Indian Ink. Silver impregnation method Fontana’s stain. Levaditi’s stain. Can also be visualized by using dark-field microscopy. Flourescent microscopy
- 23. Dark-field microscopy Simplestand most reliable method. Exudates and fluids from lesions are examined as a wet mount. Identification of T pallidum is based on the characteristic morphology and motility. This method is suitable when the lesions are moist. Examination should be done immediately after specimen collection.
- 24. •Non-Specific Treponemal Tests VDRL(lecithins)/RPR(cardiolipin) •Specific Treponemal Tests. FTA(“gold standard”, subjective) TPPA/TPHA (very sensitive) Immunoblot (good but still early days) Treponemal IgM/IgG EIA (good commercial automated screening test) Treponemal IgM (detected very early) Stay positive therefore useless for diagnosing re-infection or response to therapy.
- 25. Animal Inoculation Oldestmethod for detecting infection withT. pallidum. Rabbits were inoculated intra testicularly withT.Pallidum .
- 26. Nucleic acid amplification methods Highly sensitive Able to detect as low as one to 10 organisms per specimen with high specificity. Used to monitor treatment . Used to differentiate new infections from old infections. May be available only through select laboratories.
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- 28. Every Pregnant womenNeeds Screening
- 29. TREATMENT Penicillin isa drug of choice for primary and secondary syphilis. No antibiotic resistance has been reported. In cases of patient sensitivity to penicillin, alternate therapy with erythromycin or tetracyclines may also be effective . Despite of an inexpensive and highly effective cure, there are still over 10,000 new cases of syphilis discovers each year . There is NO VACCINE against T. pallidum
- 30. •Prevention depends onsafe sexual practices. •prompt and adequate treatment of all new cases •More than one sexually transmitted disease (STD) can be passed on at the same time. Therefore, when any STD has been diagnosed, the possibility of the infected individual also having syphilis should be considered. •For example, co-infection HIV infection makes treatment of syphilis more difficult , sometimes requiring longer courses of therapy and definitely requiring longer and more intensive follow-up.