Fritz Schaudinn (1871-1906) and Paul E. Hoffmann (1868-1959) discovered T. pallidum in serum in 1905 and 93 years later, in 1998 scientists sequenced the genome of the Treponema Pallidum.
Trepo = turm, nema= thread
Commensals treponemes
T. microdentium is found in the mouth as a part of normal flora
T. mucosum is found in genitalia as a part of normal flora.
Pathogenic treponemas:
Venereal syphilis and endemic syphilis are caused by T. pallidum
Yaws are caused by T. pertenue.
Pinta is caused by T. carateum.
Domain: Bacteria
Phylum: Spirochaetes
Order: Spirochaetales
Family: Spirochaetaceae
Genus: Treponema
Species: T. pallidum
Binomial name: Treponema pallidum
4-14×0.1-0.2 µm, thin delicate with tapering end with 10 even coils.
Coil to coil distance = 1 µm
Actively motile: back and forward movement and flexion of the whole body.
Demonstration of Treponema
Resistance
The antigenic structure of T. pallidum is complex.
Reagin antibodies that react with standard or non-specific serological test for syphilis ( antibodies that react with non -treponemal antigen).
Antigen: Combination Cardiolipin lecithin and cholesterol non-treponemal antigen have been used to detect antibodies pallidum. However, we have questions.
Is it the antigen of T. pallidum?
Is it the hapten released from tissue damage?
The above test can also be positive in other pathological conditions. e.g. acute febrile illness, immunization, pregnancy, connective tissue disease, leprosy, polyarteritis nodosa, malaria, etc.
2- Protein antigen: (Group Ag.)
This antigen is present in both pathogenic and non-pathogenic strains of T. pallidum.
eg. Reiter’s protein CFT
3. Polysaccharide antigen ( specific)
Antibodies to this antigen react only with a pathogenic strain of T. pallidum ( including Treponema causing Pinta and Yaws)
Syphilis
Syphilis is a venereal disease caused by T. pallidum leading to many structural and cutaneous lesions transmitted by direct sexual contact or in utero.
Incubation period: 10-90 days
Stage of syphilis:
Primary syphilis: 10-40 days
Stage of local ulceration and local draining leading to Lymph adenopathy.
” Hard chancre” around the genital area.
Chancres are filled with exudates and contain plenty of Spirochetes.
Secondary syphilis: (2-6 months)
Stage of generalized lymphadenopathy and hypersensitivity, characterized by rashes over skin and mucus membrane.
Tertiary syphilis:
Stage of involvement of internal organs with development of complications.
e.g. Syphilitic myocarditis
Cerebral thrombosis
Retinal thrombosis
Venereal syphilis is acquired by sexual contact. The spirochete enters to the body through minute abrasion on the skin and mucosa. It multiplies of entry.
Diagnosis of syphilis
Primary syphilis:
Specimen/s:
Exudate from:
Hard chancre
Lymph node
Darkfield microscopy for 3 days ( Sensitivity: there are 10 thousand spirochetes per ml of exudates)
TPI
FTA-ABS: Fluorescent Treponemal Antibody Absorption test
DEA-TP: Direct Fluorescent Antibody Treponema pallidum test ( in tissue and exudates)
Silver impregnation method: in biopsy
VDRL Test
TPHA
Secondary and Tertiary syphilis:
With the use of nontreponemal Antigen
Antigen: Alcoholised, Cholesterolised, Lecithinised beef heart extra cardiolipin.
It reacts with a reagin type of antibody primarily composed of IgG and IgM.
Tests:
It can also be positive other than syphilis:
With Treponemal antigen:
FTA: Fluorescent Treponemal Antibody test
TPI
Immobilization
If the Spirochetes show loss of mobility after treatment with patient sera in the following rage, The test should be interpreted as follows
More than 50% = Positive
20-50% = Doubtful
Less than 50%= Negative
Nichol’s strain OD Tp ( Formalin Killed)
Serum——– Agglutination—— Positive
(Look under Microscope)
(Von Rickenberg Phenomenon)
Table:28 Suspensions of Treponemes + Test Serum + Complement+ Fresh heparinized whole blood from a normal person
↓
Incubate
↓
Treponemes adhere to the surface of RBC
↓
Phagocyte by WBC
↓
Disappearance → Positive
Secondary and Tertiary syphilis:
Frequency of Reactive Serological test in untreated syphilis (%)
Stage VDRL TPHA FTA-ABS
Primary 70 85 55
Secondary 100 100 100
Latent or Late 70 98 98
Treatment of T. pallidum, a causative agent of syphilis is included in the following guidelines:
early latent syphilis
late latent syphilis and
congenital syphilis.
Following antibiotics are useful to treat this STI –
It cab be prevented by following ways-
PMTCT: Prevention of Mother-to-Child Transmission
RDT: Rapid Diagnostic Tests
RPR: Rapid Plasma Reagin
TPHA: Treponema pallidum Haemagglutination Assay
TPPA: Treponema pallidum Particle Agglutination Assay
TRUST: Toluidine Red Unheated Serum Test
VDRL: Venereal Diseases Research Laboratory