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Dr. Jyotsna Agarwal
Dept. Microbiology
Classification of spirochetes
• Spirochetes are thin, elongated,
spirally twisted, Gram negative
• There are 11 genera in this group
• Some are pathogens, but most are
free-living, and are actually pretty
common in the environment.
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.
Syphilis - T. pallidum
• History- ancient disease, Columbus crew
• Reservoir- humans only known natural
• Name syphilis from a poem describing a
shepherd boy
• 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
• Syphilis is conventionally divided into
following stages:
Primary, Secondary, Latent, Tertiary
–Staging has prognostic and
therapeutic implications.
Primary syphilis
• 5 to 80 days after contact (sexual), a
chancre develops at point of contactexternal 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)
• Regional lymph nodes are enlarged and
non tender
• Even before appearance of chancre,
treponema spread from site of entry via
• Multiple chancre may be seen in
immunodefficient patients.
• Once this heals patient remains
asymptomatic till secondary stage
Secondary syphilis
• 2 - 12 weeks after primary lesion
heals, generalized symptoms of
disseminated infection occur due to
multiplication and dissemination of
• 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
• Abundant spirochetes in skin lesionsmost infectious stage
• Intensity of lesions in secondary syphilis
• Can Heal spontaneously in months to
• Variable course
spontaneous cure
latent stage
go to 3rd stage
Latent Syphilis
• Absence of clinical symptoms
• 3 possible outcomes
Persist for life
Tertiary syphilis
Tertiary syphilis
• 2-20 years later
• Steady tissue destruction- Chronic
granulomata formation- Gumma,
lesions contain very few treponema
• Cardiovascular system/CNS
• ~1/3 die
Late tertiary or quaternary syphilis-
• Tabes dorsalis- dorsal column of spinal
• GPI- dementia
Congenital Syphilis
• Fetus susceptible after 4th month IU life
• 40% fetal death
• Hutchinson's Triad
peg teeth
interstitial keratitis
8th nerve destruction- deafness
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
• This is due to axial fibrils, similar
to flagella, varying numbers
• T. pallidum has not been cultured in
• It is rapidly inactivated by:
Drying, Heat, Cold
• Transmission is by direct contact or
Clinical- based on symptoms, history
• Darkfield examination
Wear gloves, Clean the lesion with
saline gauze, press it gently and
collect exudate on a slide and examine
in darkground microscope.
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
• This is a slide flocculation test to
detect antibodies in patients serum
using cardiolipin as antigen
1/3 +
95% +
latent +/-
Other Non treponemal tests
• Kahn’s- Tube flocculation test
• Wasserman test- Complement
• RPR- rapid plasma reagin test
Biological false positives- BFP
• Acute infections, major trauma,
autoimmune conditions like SLE,
• Leprosy, malaria
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)
80% +
2o & 3o >95% +
>99% +
• Penicillin is drug of choice
• Duration of tretment varies according
to clinical stage of disease
• If allergic to penicillin- Ceftriaxone
Treponema pallidum bacteria: characters
Syphilis disease: mode of transmissison
Clinical stages
Diagnostic tests: STS / Specific tests
Utility of tests / BFP