Flashcards in Syphillis Deck (16):
What pathogen causes syphilis?
What type of pathogen is Treponema pallidum?
G –ve motile Spirochete
- Very sensitive to environmental stress
- Lacks many metabolic pathways - Amino acids, nucleotides, lipids
- Culture in cells possible
- Transmitted by prolonged sexual contact and abrasion - Needles and vertical possible
- Incubation period approx 3 weeks
- Closely related species cause pinta and yaws
What are the stages of the pathogenesis of T. pallidum?
Secondary (Disseminated) Syphyilis
Describe the pathogenesis of Primary syphilis
Results from the initial infection – chancre ulcer
- Site depends interaction – results in an ulcer
3 weeks – very slow growing
- Lesion disappears after a few weeks –
- lymphadenopathy for months
- Th1 response induced during infection
Describe the pathogenesis of Secondary (disseminated) syphilis
2 – 8 weeks after chancre
- Generalised lymphadenopathy – mucocutaneous maculopapular rash – 2 – 6 weeks
- Rash contains spirochetes – infectious hands
- Latency may occur – 3 -30 years – resolution possible
Describe the pathogenesis of Tertiary syphilis
Outcome of disease depends on spread to cardiovascular or nervous system
- Gumma formation – skin bones testis
- Cardiosyphilis – colonisation of the vaso vasorum of aorta leading to necrosis – aneurisms
- Neurosyphilis – menigovasculitis, meningitis, fever, headache, mental changes – hallucinations and psychoses
Describe the pathogenesis of Congenital syphilis
T. pallidum penetrates tight junctions of cells
Foetus may be infected – 4th month
Still born or changes to skeletal structure
Anaemia, thrombocytopenia and liver failure
What proteins are involved in pathogenesis of T. pallidum? (7)
TP0155, TP0483, TP10136
TPN47, TPN17, TPf1
How are TP0155, TP0483, and TP10136 involved in the pathogenesis of syphilis?
Binds the matrix and soluble forms of fibronectin, and o allows attachment and invasion of wounds
How is TP0751 involved in the pathogenesis of syphilis?
Binds and degrades laminin and fibrinogen
- Zinc dependant membrane associated metaloprotease
- Promotes invasion - invasin
- Access to blood stream and systemic spread
- Prevents clot formation
- Access through wounds & Prevention of Containment
How are TPN47, TPN17, and TPf1 involved in the pathogenesis of syphilis?
Immune avoidance- induction of IL10 and decoy of cells
How is TrpK involved in the pathogenesis of syphilis?
Important in avoidance of the immune response
- TrpK is a target for immunity – opsinophagocytosis
- Protein is antigenically variable
- Variation begins as acquired immunity starts
- Variation occurs at transcriptional level
- Transcribed from a variety of different sites on chromosome and combined - Segmental gene conversion
- Possibly key to establishment and maintenance of latency
How is syphilis diagnosed?
Diagnosis is by serology or PCR
Serology is specific or non specific:
- Non specific - VDRL, RPR
- Specific - ElISA, FTA-ABS, MHA-TP
How is syphilis treated?
Treatment is achieved with penicillin
Very little resistance – Banzathine penicillin G
Macrolide resistance occurs – azithromycin
Can syphilis be prevented?
Vaccination is possible
- Gamma irradiated whole cells provide protection
- Other formulations only give partial protection
- Antigenic variation may be a problem