Spirochaetes are a family of bacteria characterized by their spiral shape and flexible motility. There are three main families: Treponema, which causes syphilis; Borrelia, which causes relapsing fever and Lyme disease; and Leptospira, which causes leptospirosis. Treponema pallidum, the causative agent of syphilis, has a regular spiral shape and can be seen under dark field microscopy after silver staining. Syphilis progresses through primary, secondary, and tertiary stages if left untreated. It is acquired through sexual contact and enters through skin abrasions.
3. Treponema pallidum
regular spirals
Cannot be seen by ordinary microscopy
in wet films, cannot be stain by ordinary
stains
Can be seen under dark ground
microscopy
Can be stained by silver impregnation
7. Primary syphilis
Hard chancre – at site of entry
Usually on genitalia
Covered by thick pus – rich in
treponemes
Regional lymphnodes swollen and
rubbery
Heals in 2 weeks – leaving a scar –
without treatment
12. Tertiary syphilis
Months to years after primary lesion
Represents delayed hypersensitivity
Organisms are not present in lesions
Include aneurysms, gummata,
neurological manifestations
16. Lab diagnosis
Sample – serum from chancre, gumma
Collected by scraping base/margin
Highly infectious – handle with care
Wet films examined under dark
background
DFA-TP – direct fluoroscent antibody
test for Treponema pallidum
19. VDRL
We use cardiolipin antigen obtained
from bovine heart
Look for antibodies in serum of patient
Mix serum with antigen – look for
agglutination under microscope
20. RPR – rapid plasma reagin
test
Antigen is attached to carbon particles
– can see agglutination with naked eye