Spirochetes are thin, spiral-shaped bacteria, some of which are human pathogens. Treponema pallidum causes syphilis, which has primary, secondary, latent, and tertiary stages. Syphilis is transmitted sexually and causes a painless sore initially, followed by a rash and symptoms of disseminated infection before entering latent and late stages with tissue destruction if untreated. Diagnosis involves darkfield microscopy, serology tests like VDRL and specific Treponema tests, and treatment is with penicillin.

1. Spirochetes
Dr. Jyotsna Agarwal
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

16. 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

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

20. 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.

21. 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)

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

23. 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

24. 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% +

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

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