Syphilis

Introduction

Syphilis is a bacterial infection caused by the spirochaete Treponema pallidum.
It occurs worldwide and can be classified as:

  1. Congenital Syphilis (transmitted from mother to child in utero)
  2. Acquired Syphilis (through sex or blood transfusion).

Stages of Syphilis

Syphilis is divided into stages (primary, secondary, latent, and tertiary), with different signs and symptoms associated with each stage
Primary syphilis is characterized by an ulcer or chancre at the site of infection or
inoculation.
Manifestations of secondary syphilis
include a skin rash, condyloma lata,
mucocutaneous lesions and generalized.
lymphadenopathy.
Late syphilis: late latent syphilis, gummatous, neurological and cardiovascular syphilis
This guideline is only on primary syphilis

Clinical features

  • After an incubation period of 2-4 weeks (full range 90 days) the first lesion of syphilis may appear at the site exposure most commonly, the genitals
  • Chancres may also be located on the lips or tongue; ano-rectal chancres frequently seen in male homosexuals. Begins as a small, dusky red macule which soon develops into a papule.
  • The surface of the papule erodes to form an ulcer which is typically round and painless with a clean surface and exudes a scanty
    yellow serous discharge teeming with spirochaetes
  • Lesion is indurated and feels firm or hard on palpation; surrounding skin is oedematous
  • Regional inguinal (or generalized)
    lymphadenopathy follows
  • The glands are painless, moderately
    enlarged (not buboes), discrete and never suppurate
  • Atypical lesions may be seen for various reasons e.g. bacterial superinfection, trauma or co-infection with chancroid.
  • Even without treatment, the primary lesion(s) gradually heals up and will disappear after approximately 3 – 8 weeks, sometimes leaving a thin atrophic scar which is easily overlooked.

Differential diagnoses

Other causes of genital ulcers:

  • Chancroid Herpes
  • Lymphogranuloma venerum
  • Granuloma inguinale
  • Trauma
  • Fixed drug eruption
  • Behcet’s disease
  • Erythema multiforme
  • Tuberculous ulcer
  • Amoebic ulcer
  • Cancer

Complications

  • Phimosis and paraphimosis
  • Late syphilis:
    • gummatous, neurological and cardiovascular syphilis

Investigations

  • Dark field examination
  • Direct fluorescent antibody tests of lesion exudates or tissue
  • VDRL
  • RPR

Treatment objectives

  • Eliminate the organism in the patient and sexual partner(s)
  • Prevent re-infection
  • Prevent complications
  • Counsel and screen for possible co-infection with HIV so that appropriate management can be instituted

Drug therapy

Recommended regimen:

  • Benzathine benzylpenicillin – 4g (2.4 million units) by intramuscular injection, at a single session
    • Because of the volume involved, this dose is usually given as two injections at
      separate sites.

Alternative regimen for penicillin-allergic (non -pregnant) patients

  • Doxycycline 100 mg orally, every 12 hours for 14 days

Or:

  • Tetracycline 500 mg orally, every 6 hours for 14 days

Alternative regimen for penicillin-allergic pregnant patients

  • Erythromycin 500 mg orally, every 6 hours for 14 days

Notable adverse drug reactions, caution and contraindications

Benzylpenicillin (Penicillin G)

  • Caution in patients with history of allergy; atopic patients; in severe renal impairment, neurotoxicity; high doses may cause convulsions
  • Contraindicated in penicillin hypersensitivity
  • May cause hypersensitivity reactions including! urticaria, fever, joint pains, rashes, angioedema, anaphylaxis, serum sickness-like reaction, rarely intestitial
    nephritis, haemolytic anaemia,
    leucopaenia, thrombocytopaenia and coagulation disorders

Other antibiotics
See Chlamydia

Prevention

  • Counselling, Compliance, Condom use and Contact treatment
  • All infants born to seropositive mothers should be treated with a single intramuscular dose of benzathine penicillin 50,000 units/kg, whether or not the mothers were treated during pregnancy (with or without penicillin).
  • Prevention of congenital syphilis is feasible
  • Programmes should implement effective screening strategies for syphilis in pregnant women
  • Screening for syphilis should be conducted at the first prenatal visit
  • Some programmes have found it beneficial to repeat the tests at 28 weeks of pregnancy and at delivery in populations with a high
    incidence of congenital syphilis