2. INTRODUCTION
• Spirochaetes are elongated, motile, flexible bacteria
twisted spirally along the long axis. (Speira – meaning coil
and chaite – meaning hair).
• Structurally more complex than other bacteria.
Characteristic feature is the presence of varying numbers
of endoflagella, which are polar flagella wound along the
helical protoplasmic cylinder, and situated between the
outer membrane and cell wall.
• Endoflagella are responsible for motility.
3. Order-Spirochetales
• Family- (a) Spirochetaceae;(Genera Treponema &
Borrelia)
(b) Leptospiraceae(Genera Leptospira )
• Human pathogens are found in the genera
– Treponema
– Borrelia
– Leptospira.
• Genus Spirochaeta are saprophytes found in
water and sewage
4. TREPONEMA
• Treponemes (trepos, meaning to turn, and
nema, meaning thread) are relatively short
slender spirochetes with fine spirals and
pointed or rounded ends.
• Some of them are pathogenic, while others
occur as commensals in the mouth,
intestines, and genitalia.
• Pathogenic treponemes are NOT
CULTIVIABLE on ordinary media though
commensals can be grown in artificial
media.
5. TREPONEMA
• Treponemes cause following diseases
in humans :
– Venereal syphilis caused by T. pallidum.
– Endemic syphilis caused by T. pallidum
(T. endemicum)
– Yaws caused by T. pertenue.
– Pinta caused by T. carateum.
• They are almost identical in their
morphology, antigenic structure and
other features but show differences
in their clinical features and natural
history of the diseases they produce.
6. Treponema pallidum
• Treponema pallidum, the causative agent of
syphilis, was discovered in the chancres and
inguinal lymph nodes of syphilitic patients.
The name pallidum refers to its pale staining.
7. Treponema pallidum
• Morphology:- A thin delicate spirochete with
tapering ends, about 10µm long (range 4-
14µm) and 0.1-0.2µm wide. It has about ten
regular spirals, which are sharp and angular, at
intervals of about 1µm.
• It is actively motile, exhibiting rotation around
the long axis, backward and forward
movement, and flexion of the whole
body.(Corkscrew motility)
8. Microscopy
• In wet films cannot be seen under
light microscopy but can be made out
by negative staining with India ink.
• Motility and morphology can be seen
under Dark Ground Illumination(DGI)
& Phase Contrast Microscope.
• Gram negative bacilli. Does not take
ordinary bacterial stains. Prolonged
Giemsa staining – stains light rose red.
• Stained by silver impregation
methods
– Fontana’s method for films/smears
– Levaditi’s method for tissue sections.
10. Cultural characteristics
• T. pallidum do not grow in artificial culture
media.
• Maintained in motile and virulent form for
10-12 days in complex media under
anaerobic conditions.
• Serial testicular passage in rabbits
maintain virulent T.pallidum for many
decades eg. Nichol’s strain.
• Reiter strain (T.phagedenix), nonpathogenic
treponeme, grows well in thioglycollate
medium.
11. Resistance
• T.pallidum is very a delicate organism.
• Readily inactivated by drying or heat(41-42oC in
1hr).
• Killed in 1-3 days at 0-4oC. Transfusion syphilis
prevented by storing blood for atleast four days in
the fridge before transfusion.
• Remains viable for 10-15 years at -70oC in 10%
glycerol, or in liquid nitrogen(-130oC).
• Inactivated by contact with oxygen, distilled
water, soap, common antiseptic agents and
antibiotics.
12. 12
Pathology
•
• Penetration:
– T. pallidum enters the body via skin and mucous
membranes through abrasions during sexual contact
– Also transmitted transplacentally
– Infective dose is small (60 treponemes being capable
of infection).
• Dissemination:
– Travels via the lymphatic system to regional lymph
nodes and then throughout the body via the blood
stream
– Invasion of the CNS can occur during any stage of
syphilis
13. STAGES OF SYPHILIS
1. Primary
2. Secondary
3. Latent
•
•
Early latent
Late latent
1. Late or tertiary
• May involve any organ, but main parts are:
– Neurosyphilis
– Cardiovascular syphilis
– Late benign (gumma)
14. Clinical significance
• The first symptom of primary syphilis is a
hard, painless genital or oral ulcer (chancre)
that develops at the site of inoculation.
• The average period between infection and
the appearance of the chancre is about 3
weeks but varies with the number of
infecting organisms.
• This primary lesion heals spontaneously,
but the organism continues to spread
throughout the body via the lymph and
blood.
• An asymptomatic period ensues, lasting as
long as 24 weeks, followed by the secondary
stage.
15. Clinical significance
• The Secondary stage is characterized by
the appearance of a red,
maculopapular rash on almost any part
of the body, including the palms of the
hands and soles of the feet.
• Pale, moist, flat papules seen primarily
in the anogenital region, armpits, and
mouth.
• Both primary and secondary lesions
teem with T. pallidum and are extremely
infectious.
• The secondary stage may be
accompanied by multiorgan
involvement, causing hepatitis,
meningitis, nephritis.
17. Tertiary stage
• Upon healing of the secondary lesions, the disease
enters a latent period that can last for many years.
• In approximately 40 percent of infected individuals,
the disease progresses to a tertiary stage.
• Characterized by degeneration of the nervous system;
cardiovascular lesions and granulomatous lesions
(gummas) in the liver, skin, and bones.
18. Congenital Syphilis
• Congenital syphilis
usually occurs following
vertical transmission of
T. pallidum from the
infected mother to the
fetus in utero, but
neonates may also be
infected during passage
through the infected
birth canal at delivery.
18
20. • Lab aid essential for – Diagnosis of disease &
Assessing cure after treatment
• Lab diagnosis consists of demonstration of
– Spirochetes under the microscope (microscopy)
– Antibodies in serum or CSF (serological test)
• Microscopy – done in primary and secondary
stages & congenital syphilis
– Wet films examined under DGI
– Direct fluorescent antibody test (DFA-TP)
• Serological tests – mainstay of lab diagnosis.
Classified as follows:-
– Tests for Ab to cardiolipin Ag
– Tests for Ab to group specific (treponemal Ag)
– Tests for Ab to species specific Ag (T.pallidum)
21. Sample collection
For direct examination, exudates from lesions
of primary, secondary and early congenital
syphilis are the most useful.
Clear, serous fluid free of erythrocytes, tissue
debris.
Serum is the specimen of choice for both
nontreponemal and treponemal serological
tests.
Cerebrospinal fluid (CSF) testing is indicated
in congenital and tertiary syphilis and when
neurological symptoms are present.
22. Microscopy
Can be seen with :
Negative staining with Indian Ink.
Silver impregnation method
Fontana’s stain.
Levaditi’s stain.
Can also be visualized by using dark-field
microscopy.
Flourescent microscopy
23. Dark-field microscopy
Simplest and most reliable method.
Exudates and fluids from lesions are
examined as a wet mount.
Identification of T pallidum is based on the
characteristic morphology and motility.
This method is suitable when the lesions are
moist.
Examination should be done immediately
after specimen collection.
24. •Non-Specific Treponemal Tests
VDRL (lecithins)/RPR(cardiolipin)
•Specific Treponemal Tests.
FTA(“gold standard”, subjective)
TPPA/TPHA (very sensitive)
Immunoblot (good but still early days)
Treponemal IgM/IgG EIA (good commercial automated
screening test)
Treponemal IgM (detected very early)
Stay positive therefore useless for diagnosing re-infection or response to therapy.
25. Animal Inoculation
Oldest method for detecting infection withT.
pallidum.
Rabbits were inoculated intra testicularly
withT.Pallidum .
26. Nucleic acid amplification
methods
Highly sensitive
Able to detect as low as one to 10 organisms per
specimen with high specificity.
Used to monitor treatment .
Used to differentiate new infections from old
infections.
May be available only through select
laboratories.
29. TREATMENT
Penicillin is a drug of choice for primary and
secondary syphilis.
No antibiotic resistance has been reported.
In cases of patient sensitivity to penicillin, alternate
therapy with erythromycin or tetracyclines may also
be effective .
Despite of an inexpensive and highly effective cure,
there are still over
10,000 new cases of syphilis discovers each year .
There is NO VACCINE against T. pallidum
30. •Prevention depends on safe sexual practices.
•prompt and adequate treatment of all new cases
•More than one sexually transmitted disease (STD)
can be passed on at the same time. Therefore, when
any STD has been diagnosed, the possibility of the
infected individual also having syphilis should be
considered.
•For example, co-infection HIV infection makes
treatment of syphilis more difficult , sometimes
requiring longer courses of therapy and definitely
requiring longer and more intensive follow-up.
