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Spirochetes

Spirochetes. Dr. Jyotsna Agarwal Dept. Microbiology KGMU. Classification of spirochetes. Spirochetes are thin, elongated, spirally twisted, Gram negative bacteria There are 11 genera in this group

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Spirochetes

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  1. Spirochetes Dr. JyotsnaAgarwal Dept. Microbiology KGMU

  2. Classification of spirochetes • Spirochetes are thin, elongated, spirally twisted, Gram negative bacteria • There are 11 genera in this group • Some are pathogens, but most are free-living, and are actually pretty common in the environment.

  3. 3 genera have human pathogens Treponema, Borrelia, leptospira Treponema(25 species)- Relatively short, slender, fine spirals. Associated with venereal and non venereal diseases, some are non pathogenic Treponema pallidum causes syphilis- venereal disease- STD.

  4. Syphilis - T. pallidum • History- ancient disease, Columbus crew • Reservoir- humans only known natural host. • Name syphilis from a poem describing a shepherd boy

  5. Transmission- sexual route- venereal • Syphilis is not very contagious; a person has 1/10 chance of becoming infected after contact with an infected person • In some stages, it is less contagious

  6. Syphilis is conventionally divided into following stages: Primary, Secondary, Latent, Tertiary • Staging has prognostic and therapeutic implications.

  7. Primary syphilis • 5 to 80 days after contact (sexual), a chancre develops at point of contact- external genitalia • Chancre is an inflammatory lesion containing spirochetes & lymphocytes. • It is painless, well circumscribed,indurated, heals spontaneously after ~10 – 40 days leaving a thin scar.(also called hard chancre)

  8. Regional lymph nodes are enlarged and non tender • Even before appearance of chancre, treponema spread from site of entry via blood/lymph. • Multiple chancre may be seen in immunodefficient patients. • Once this heals patient remains asymptomatic till secondary stage

  9. Secondary syphilis • 2 - 12 weeks after primary lesion heals, generalized symptoms of disseminated infection occur due to multiplication and dissemination of treponemes • Fever, headache, sore throat and enlarged lymph nodes develop • Papular skin rash develops on body and lesions appear on palms and soles of feet also

  10. Abundant spirochetes in skin lesions- most infectious stage • Intensity of lesions in secondary syphilis varies • Can Heal spontaneously in months to years • Variable course spontaneous cure latent stage go to 3rd stage

  11. Latent Syphilis • Absence of clinical symptoms • 3 possible outcomes Persist for life Tertiary syphilis Cure

  12. Tertiary syphilis • 2-20 years later • Steady tissue destruction- Chronic granulomata formation- Gumma, lesions contain very few treponema • Cardiovascular system/CNS • ~1/3 die

  13. Late tertiary or quaternary syphilis- • Tabes dorsalis- dorsal column of spinal cord • GPI- dementia

  14. Congenital Syphilis • Fetus susceptible after 4th month IU life • 40% fetal death • Hutchinson's Triad peg teeth interstitial keratitis 8th nerve destruction- deafness

  15. Treponema pallidum bacteria • It is slender and tightly coiled, measuring 5 to 15 µm long by 0.09 to 0.18µm wide • They have a characteristic motility on dark field microscopy- cork screw • This is due to axial fibrils, similar to flagella, varying numbers

  16. T. pallidum has not been cultured in vivo. • It is rapidly inactivated by: Drying, Heat, Cold • Transmission is by direct contact or congenitally

  17. Diagnosis Clinical- based on symptoms, history Laboratory • Darkfield examination Wear gloves, Clean the lesion with saline gauze, press it gently and collect exudate on a slide and examine in darkground microscope.

  18. Serologic tests Non Specific/Non treponemal • A reactive material from beef heart called cardiolipin is used as antigen • It reacts with “reagin” antibodies that develop in syphilis • Also called Standard test for Syphilis (STS)

  19. VDRL • This is a slide flocculation test to detect antibodies in patients serum using cardiolipin as antigen 1o 1/3 +2o 95% +latent +/-

  20. Other Non treponemal tests • Kahn’s- Tube flocculation test • Wasserman test- Complement fixation • RPR- rapid plasma reagin test Biological false positives- BFP • Acute infections, major trauma, autoimmune conditions like SLE, • Leprosy, malaria

  21. Specific - treponemal tests Using T. pallidum antigen to detect antibodies in patients serum • Treponema pallidum immobilization- TPI • Fluorescent treponemal Antibody (FTA) • T pallidum haemagglutination (TPHA) 1o 80% + 2o & 3o >95% + latent >99% +

  22. Treatment • Penicillin is drug of choice • Duration of tretment varies according to clinical stage of disease • If allergic to penicillin- Ceftriaxone

  23. Summary • Treponema pallidum bacteria: characters • Syphilis disease: mode of transmissison • Clinical stages • Diagnostic tests: STS / Specific tests • Utility of tests / BFP

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