Syphilis

Question 1

Definition

Answer 1

Syphilis is a systemic infection caused by the gram -ve spirochete (Treponema pallidum)

• Aetiology – sexual contact, blood-borne, or vertical
• Risk factors – young (age <29 years), African American, use of illicit drugs, infection with other STIs, sex worker

Question 2

Signs and symptoms

Answer 2

Primary (3-4w) – painless chancres ± local lymphadenopathy Resolves in 3-8w

 
Secondary (4-10w after chancre) – only 25% get symptoms… Resolves in 2-12w

• Rough papulonodular rash (hands, feet, trunk)
• Uveitis
• Condylomata Lata
• Lymphadenopathy + systemic symptoms

Latent (no symptoms; detected on routine tests) – guides management:

• Early latent (<2 year after infection – exposure to OR symptoms of 1st/2nd S/S in <2 year)
• Late latent (>2 year after infection – exposure to OR symptoms of 1st/2nd S/S in >2 year)

 

Tertiary (1 to 20 years) – affects 1/3rd of untreated illness:

• Gummatous syphilis / 15% (erosive skin and bone lesions)
• Cardiovascular syphilis / 10% (aortitis, aortic regurgitation (early diastolic decrescendo), heart failure)
• Neurosyphilis – types (n.b. tabes dorsalis affects the dorsal columns):
  
  • Meningovascular (5-10 years)  ischaemia, insomnia, emotionally labile
  • General paresis (10-25 years)  dementia
  • Tabes dorsalis (15-20 years)  sensory problems, lightning pains, absent reflexes

Question 3

Investigations

Answer 3

Microbiology – dark-ground (from chancre with dark-field illuminations), PCR

Serology – routine antenatal screening offered to all pregnant women  detects treponemal antibodies

• N.B. it takes 3/12 for syphilis to become positive in serology…
• Non-treponemal tests – high false positive rate due to cross-reactivity (i.e. with EBV)
  
  • RPR (rapid plasmin reagin) – dilutional ratios – i.e. how many dilutions to lose the reagin:
  • Examples:
  • 1: 2 = need to dilute to 1: 2 to lose the reagin (i.e. low levels of reagin)
  • 1: 512 = need to dilute to 1: 512 to lose the reagin (i.e. high levels)
  • N.B. sero-fast = stable ratio 1 either side of each test (i.e. 1: 8, 1: 4, 1: 16 = sero-fast)

If positive, must be followed up by a more specific treponemal test

VDRL (venereal disease research laboratory) test

Treponemal tests:

• EIA – very sensitive and specific (if positive, likely to have syphilis)
• TPHA / TPPA (treponema pallidum haemagglutinin assay)
• FTA-ABS (fluorescent treponemal antibody absorption)

Neurosyphilis  CT/MRI head, LP (raised WCC, raised protein), TPPA >1: 320

Question 4

Management

Answer 4

(mother; any adult):

Early (1st and 2nd, early latent): Benzathine-Pen (IM, STAT) OR doxycycline (BD, 14/7)

Late (late latent, 3rd): Benzathine-Pen (IM, OW, 3/52) OR doxycycline (BD, 28/7)

Neurosyphilis: Benzyl Penicillin (IV, 4-hourly, 14/7) OR doxycycline (BD, 28/7)

• Prednisolone (OD, 3/7) started 24 hours before treatment to avoid Jarish-Herxheimer reaction
• Jarish-Herxheimer reaction = release of proinflammatory cytokines in response to dying organisms
• S/S: 24 hours of a febrile myalgia – rare/serious consequences – admit mothers >22w when treating

Follow-up: partner notification, repeat bloods at 3/12 (4-fold drop in RPR)

Question 5

Complications

Answer 5

(of pregnancy) -> congenital syphilis (PTL, still birth 25% if not treated, miscarriage)

• Rash on soles of feet and hands
• Bloody rhinitis
• Hepatosplenomegaly
• Glomerulonephritis
• ‘Hutchinson’s teeth’ (small, widely spaces, notched)
• Frontal bossing of skull, saddle-nose deformity
• ‘Saber’s shins (anterior bowing of shins)
• ‘Clutton’s joints’ (symmetrical knee swelling)