Spirochetes , Borrelia and laptospiria

Spirochetes

By:Dr. Kareema Amine Al-Khafajii ,Assistant Professor, Babylon University ,College Of Medicine, Department Of Microbiology .
Spirochetes are bacteria with a spiral morphology ranging from loose coils to a rigid corkscrew shape. thin (0.1-0.5M) ,long(5-20M), Gram negative bacteria, motile by periplasmic flagella.
Morphology and structure:
The spiral morphology of spirochetes is produced by a flexible, peptidoglycan cell wall around which several axial fibrils are wound. The cell wall and axial fibrils are completely covered by an outer bilayered membrane similar to the outer membrane of other Gram-negative bacteria. In some species, a hyaluronic slime layer forms around the exterior of the organism and may contribute to its virulence. Spirochetes are motile, exhibiting rotation and flextion; this motility is believed to result from movement of the axial filaments, although the mechanism is not clear.
Many spirochetes are difficult to see by routine microscopy. Although they are Gram-negative, many either take stains poorly or are too thin (0.15Mm or less) to fall within the resolving power of the light microscope. only darkfield microscopy,immunofluorescence, or special staining techniques can demonstrate these spirochetes. Other spirochetes such as Borrelia are wider and readily visible in stained prepration,even routine blood smears.
Three genera of Spirochetes are pathogenic to man:
1-Treponema, 2-Borrelia ,3- Leptospira
1-The Treponema:
*Classification: Treponema pallidum causing syphilis (venereal disease)
Other Treponema:
1-T.palidum subspecies endemicum causing Bejel (endemic syphilis).
2- T.palidum subspecies pertenue causing Yaws
3-T.carateum causing Pinta.
Bejel, Yaws and Pinta are non-venereal diseases.
Morphology , Structure, and Physiology:
*The microorganism is so thin , tightly coiled with straight end, and not seen by stained smears.