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Flashcards in Syphillis Deck (16):
1

What pathogen causes syphilis?

Treponema pallidum

2

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

3

What are the stages of the pathogenesis of T. pallidum?

Primary Syphilis
Secondary (Disseminated) Syphyilis
Tertiary Syphilis
Congenital Syphilis

4

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

5

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

6

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

7

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

8

What proteins are involved in pathogenesis of T. pallidum? (7)

TP0155, TP0483, TP10136
TP0751
TPN47, TPN17, TPf1
TrpK

9

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

10

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

11

How are TPN47, TPN17, and TPf1 involved in the pathogenesis of syphilis?

Immune avoidance- induction of IL10 and decoy of cells

12

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

13

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

14

How is syphilis treated?

Treatment is achieved with penicillin
Very little resistance – Banzathine penicillin G
Macrolide resistance occurs – azithromycin

15

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

16

Describe the treatment regimen for syphilis infection

The following regimens are recommended for penicillin treatment:
- Primary or secondary syphilis - Benzathine penicillin G 2.4 million units intramuscularly (IM) in a single dose

- Early latent syphilis - Benzathine penicillin G 2.4 million units IM in a single dose

- Late latent syphilis or latent syphilis of unknown duration - Benzathine penicillin G 7.2 million units total, administered as 3 doses of 2.4 million units IM each at 1-week intervals

- Pregnancy - Treatment appropriate to the stage of syphilis is recommended.