Gonorrhoea

Curable sexually transmitted infection caused by Neisseria gonorrhoeae

Aetiology

Causative organism:
  • Neisseria gonorrhoeae
Microbiological characteristics:
  • Gram-negative, kidney-shaped diplococci
  • Intracellular (commonly found within neutrophils)
  • Non-motile, non-spore forming
  • Oxidase-positive
  • Ferments glucose (not maltose)
Virulence factors (key in pathogenesis):
  • Pili: adhesion to epithelial cells, antigenic variation → immune evasion
  • Outer membrane proteins (PorB, Opa): invasion and immune resistance
  • Lipooligosaccharide (LOS): endotoxin → inflammation

Pathophysiology

  1. Attachment of bacteria to mucosal epithelium via pili
  1. Penetration into epithelial cells
  1. Local multiplication and neutrophil recruitment
  1. Acute inflammation with purulent discharge
  1. Possible ascending spread or hematogenous dissemination
Importantly:
  • No protective immunity → reinfection common
  • Antigenic variation explains recurrent disease

Clinical presentation

Males

Gonococcal urethritis
  • Incubation: 2–7 days
  • Symptoms:
    • Profuse, purulent, yellow-green urethral discharge
    • Dysuria
    • Urethral itching
  • Examination:
    • Meatal erythema
    • Expressible pus

Females

Gonococcal cervicitis (often asymptomatic)
  • Symptoms (if present):
    • Vaginal discharge
    • Intermenstrual or post-coital bleeding
    • Dysuria
  • Signs:
    • Mucopurulent endocervical discharge
    • Cervical friability
Venereology principle:
Females frequently serve as asymptomatic reservoirs, contributing to disease spread.

Investigations

Direct Microscopy

  • Gram stain
    • Intracellular gram-negative diplococci
    • Highly sensitive in symptomatic males
    • Less reliable in females and extragenital sites

Nucleic Acid Amplification Tests (NAATs)

  • Gold standard
  • High sensitivity and specificity
  • Can test urine and swabs (urethral, cervical, rectal, pharyngeal)

Culture

  • Required for:
    • Antimicrobial resistance testing
  • Uses Thayer-Martin or chocolate agar

Management

  • First line: ceftriaxone 1G IM
  • Second line: cefixime 400mg oral + azithromycin 2G (only if IM injection is contraindicated or refused by patient)
  • Test of cure in all patients

Complications

Lower genital tract

  • Bartholinitis
  • Tysonitis
  • Periurethral abscess
  • Rectal abscess
  • Epididymitis
  • Urethral stricture

Upper genital tract

  • Endometritis
  • PID
  • Hydrosalpinx
  • Infertility
  • Ectopic pregnancy
  • Prostatitis