Syphilis

exp date isn't null, but text field is

Introduction

  • Infection caused by the spirochaete Treponema pallidum which occurs worldwide
  • Can be classified as:
    • Congenital (transmitted from mother to child in utero)
    • Acquired (through sex or blood transfusion) early or late
  • Primary syphilis is characterized by an ulcer or chancre at the site of infection or inoculation
  • Secondary syphilis includes a skin rash, condyloma lata, mucocutaneous lesions and generalized lymphadenopathy
  • Late syphilis: late latent syphilis, gummatous, neurological and cardiovascular syphilis

This section 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 of 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 or RPR

Treatment goals

  • 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 treatment

Recommended regimen:

Benzathine benzylpenicillin - 4g (2.4 million units) by intramuscular injection, ata 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, contraindications and caution 

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

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