1. Dr. Jyotsna Agarwal Dept. Microbiology KGMU
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. Treponema, Borrelia, leptospira
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
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 /3 + 2o % + 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 % +
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