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Spirochaetes

Spirochaetes. By. Dr. Emad AbdElhameed Morad. Lecturer of Medical Microbiology and Immunology. Spirochaetes are long, slender, spiral organisms which are motile by periplasmic internal flagellae . Spirochaetes include three genera:. Treponema. Borrelia. Leptospira.

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Spirochaetes

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  1. Spirochaetes By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology

  2. Spirochaetes are long, slender, spiral organisms which are motile by periplasmic internal flagellae. • Spirochaetes include three genera: Treponema Borrelia Leptospira

  3. Treponema pallidum

  4. Morphology Delicate spiral filaments with small and regularcoils. Cork screw like motility. Seen only by dark ground microscope. Not stained by Gram stain. Could be stained by silver, Fontana stain and immunofluorescence.

  5. Treponema by Fontana stain

  6. Cultural characters Pathogenic treponema has not been cultivated on artificial media. However, Nichol’s strain can be maintainedin the testicles of rabbits. Saprophytic or non pathogenic treponema (Reiter strain) could be cultivated anaerobically invitro.

  7. Serological characters On exposure to Treponema pallidum, the body produces two types of antibodies: Specific antitreponemal antibodieswhich react with Treponema pallidum. Reagin antibodywhich reacts with non specific antigen calledcardiolipin.

  8. Virulence factors The outer membrane proteins: mediate adherence. Hyaluronidase enzyme: help perivascular infiltration.

  9. Syphilis It is a venereal disease which is transmitted by: Sexual intercourse. It could be transmitted by contact infection. It could be transmitted also from mother to fetus (congenital). Blood transfusion. Stages of syphilis: Primary syphilis: the lesion is rich in treponema. Secondary syphilis: rich in treponema + Positive serology Latent stage: no symptoms or signs + positive serology. Tertiary syphilis: the lesion has no treponema + positive serology.

  10. Primary syphilis (Chancre) Hard painless ulcer (hard sore) + enlarged LNs. Occurs 2-10 weeks after exposure. On the site of contact mainly genitalia. Rich in treponema.

  11. Secondary syphilis Skin rash Condylomata Mucous patches Appears 6-12 weeks after appearance of chancre. Skin rash + condylomata lata of the anus and vulva + mucous patchesin the mouth. These lesions are rich in treponema.

  12. Tertiary syphilis Occurs in 30% of untreated cases. Granuloma (gumma) appear in the: Skin and bones. Central nervous system: causing tabes dorsalis. Cardiovascular system: causing aortic aneurysm. Treponema is not present in gumma. Diagnosed by serology.

  13. Laboratory diagnosis Direct IF Detection of treponema in the lesion: * Exudate from lesions of primary or secondary syphilis is examined by: Dark ground microscope to show motile spirochaetes. Direct immunofluorescence. PCR.

  14. Non treponemal antigen tests Serological diagnosis: * There are two kinds of serological tests according to the antigen used: Treponemal antigen tests

  15. Non treponemal antigen tests • The antigen used is cardiolipin which is alcoholic extract of beef heart muscle + cholesterol + lecithin. • Detect reagin antibodies. • Non specific. Give positive results in other diseases such as measles, leprosy, malaria, hepatitis B. • So, positive test should be confirmed by specific treponemal antigen tests. Disadvantages

  16. Advantages • Rapid, simple, cheap • Used for screening for epidemiological purposes. • Evaluate the effect of treatment because they become negative in 6-18 months after effective treatment. • Venereal disease research laboratory (VDRL). • Rapid plasma reagin (RPR). • Toluidine red unheated serum test (TRUST). They are:

  17. Venereal disease research laboratory (VDRL): • It is a flocculation test. • It requires heat inactivation of the serum. • Read under the microscope. • Rapid plasma reagin (RPR): • It is a flocculation test using black particles. • It does not require heat inactivation of the serum. • It is read with naked eye. • Toluidine red unheated serum test (TRUST): • Similar to RPR • But, red particles instead of black carbon particles are used to visualize the reaction

  18. Treponemal antigen tests • The antigen used is specific Treponema pallidum antigen. • Detect antitreponemal antibodies. • Highly specific. • Complex and expensive. • So, used mainly as confirmatory tests. • Remain positive for life even after effective treatment. Advantages Disadvantages

  19. They are: • Fluorescent treponema antibody absorption (FTA-ABS) test. • Treponema pallidum hemagglutination (TP-HA) test. • Treponema pallidum particle agglutination (TP-PA) test. • ELISA • Western blot.

  20. FTA-ABS test: • Indirect immunofluorescence. • TP-HA test: • It depends on the ability of antitreponemal antibodies to cause agglutination of sheep red cells coated with extract of Treponema pallidum. • TP-PA test: • It depends on the ability of antitreponemal antibodies to cause agglutination of gelatin particles coated with extract of Treponema pallidum. • ELISA or western blot.

  21. Treatment Penicillin is the drugs of choice.

  22. GOOD LUCK

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