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General Overview of Spirochaetales

General Overview of Spirochaetales. Gram-negative spirochetes Spirochete from Greek for “coiled hair” Extremely thin and can be very long Tightly coiled helical cells with tapered ends Motile by Periplasmic flagella (axial fibrils or endoflegalla). Human pathogen. Treponema

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General Overview of Spirochaetales

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  1. General Overview of Spirochaetales • Gram-negative spirochetes • Spirochete from Greek for “coiled hair” • Extremely thin and can be very long • Tightly coiled helical cells with tapered ends • Motile by Periplasmic flagella (axial fibrils or endoflegalla) Dr.T.V.Rao MD

  2. Human pathogen Treponema Borreilia Leptospira

  3. How they appear

  4. Spirochaetales Associated Human Diseases

  5. Treponemapallidum

  6. Treponema pallidum Morphology • Motile, sluggish in viscous environments • Size: 5 to 20 μm in length & 0.09 to 0.5 μm in diameter, with tapered ends • Can be seen on fresh primary or secondary lesions by dark field microscopy or fluorescent antibody techniques

  7. Staining with special stains Staining by Giemsa and Fontana

  8. Dark field Microscopy

  9. Cultivation of .. ? Treponemescannot be cultivated in laboratory media and are maintained by subculture in susceptible animals.

  10. Primary Syphilis - Chancre

  11. Secondary Syphilis

  12. Secondary Syphilis

  13. Secondary Syphilis

  14. Secondary syphilis

  15. Diagnosis of syphilis A. Direct detection of spirochetes : Darkfield microscopy Silver stain B. Culture : not used C. Serology: non-specific and specific tests

  16. Venereal Disease Research Laboratory - VDRL

  17. 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.

  18. Treponema pallidum haemagglutination (TPHA) • Adapted to micro techniques (MHA-TP) • Tanned sheep RBCs are coated with T. pallidum antigen from Nichol’s strain. • Agglutination of the RBCs is a positive result.

  19. Serologic Tests All positive nontreponemal test results should be confirmed with a specific treponemal test

  20. Every Pregnant women Needs Screening

  21. Borreliaburgdorferi and Lyme disease 23

  22. B. burgdorferi - Causes Lyme disease, transmitted by the bite of Ixodid ticks (deer tick) - Diagnosis– serological tests

  23. Diagnosis • - serum antibodies toB. burgdorferi • laboratory strains grow extremely slowly tissue • culture media not bacteriological media. • patient body fluids/tissue sample almost never • grow 25

  24. - B. recurrentisOnly detected on blood smear 26

  25. Leptospirosis 27

  26. Leptospira - Very thin, delicate spirochetes with hooked ends - 2 species are recognised: • L. interrogans– pathogenic to human (rats are the reservoir) • L. biflexa – saprophytic, mainly found in surface water.

  27. L. interrogansinsilver stained smear, hooked ends resemble umbrella handles

  28. - Transmission - Leptospires in water contaminated by the urine of rats

  29. Diagnosis - Examination of blood – 1st week only - Urine– 2nd week of disease, should be examined immediately after voiding - Serology– Abs appear by the end of 1st week & increase till 4th week of disease.

  30. Microbiology • Obligatory intracellular bacteria • Infect columnar epithelial cells • Survive by replication that results in the death of the cell • Takes on two forms in its life cycle: • Elementary body (EB) • Reticulate body (RB)

  31. Chlamydiaceae Family(species that cause disease in humans)

  32. Chlamydial inclusion bodies (Giemsa smear)

  33. Chlamydial inclusion bodies (Giemsa smear)

  34. Chlamydial inclusion bodies (immunofluorescent stain)

  35. Chlamydial inclusion bodies (immunofluorescent stain)

  36. Culture - Historically the “gold standard” - Variable sensitivity (50%-80%) - High specificity - Use in legal investigations - Not suitable for widespread screening

  37. NAATs - NAATs amplify and detect organism-specific genomic or plasmid DNA or rRNA - Significantly more sensitivity than other tests

  38. Non-Amplication Tests - Direct fluorescent antibody (DFA) - Detects intact bacteria with a fluorescent antibody - Variety of specimen sites - Enzyme immunoassay (EIA) - Detects bacterial antigens with an enzyme-labeled antibody - Nucleic acid hybridization (NA probe) - Detects specific DNA or RNA sequences of C. trachomatis and N. gonorrhoeae

  39. Why Screen for Chlamydia? - Screening can reduce the incidence of PID by more than 50%. - Most infections are asymptomatic. - Screening decreases the prevalence of infection in the population and reduces the transmission of disease.

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