Chlamydia trachomatis

From IDWiki
Chlamydia trachomatis

Background

Microbiology

  • Small, obligate intracellular Gram-negative coccobacillus
    • Very difficult to Gram stain due to lack of peptidoglycan in cell wall
  • Two forms exist:
    • Elementary body (EB): spore-like form than can survive short times outside the body
    • Reticulate body (RB): replicative form
  • Virulence factors include lipopolysaccharide (LPS)

Risk Factors

  • Sexual contact with chlamydia-infected person
  • New sexual partner, or more than two sexual partners in the past year
  • Previous STI
  • Specific populations: people who inject drugs, incarcerated people, sex trade workers, street-living youth

Clinical Manifestations

Serovars Syndromes
A to C Trachoma (chronic conjunctivitis)
D to K Urethritis, PID, neonatal infection
L1 to L3 Lymphogranuloma venereum (LGV)

Sexually-Transmitted Infection

Lymphogranuloma Venereum

Fitz-Hugh-Curtis syndrome

  • Liver capsular inflammation, possibly autoimmune

Pediatric Infections

  • Serovars associated with STIs can also cause:
    • Conjunctivitis in neonates
    • Pneumonia in children under 6 months of age

Trachoma

  • Chronic keratoconjunctivitis caused by recurrent infection
  • Leading infectious cause of blindness worldwide
  • Spread via direct contact of ocular or nasal secretions and via fomites, and possibly via eye-seeking flies including Musca sorbens
  • Presents with two phases:
    • Active trachoma, with acute, mild, self-limited conjunctivitis
      • May be asymptomatic
      • Usually detected with screening
    • Cicatricial disease causing conjunctival scarring
      • Scar tissue distorts the eyelid margin, causing entropion (the eyelid turned inwards)
      • Entropion causes trichiasis, where the eyelashes rub against the eye and cause scarring
      • Eventually leads to blindness

Diagnosis

  • Molecular testing
    • Urine NAAT is ~80% sensitive, and is preferred when there is no other indication for a pelvic examination
    • Self-collected vaginal swab likely has better sensitivity, though
    • MD-collected cervical swab best sensitivity (90+%)
  • Culture
    • For throat specimens
    • Done in cell culture
  • Serology
    • IgM antibodies can be helpful for diagnosting pneumonia in infants under 3 months of age
    • Not helpful for diagnosing genital infections

Management

Adults

  • Non-pregnant, non-lactating adults with urethral, endocervical, rectal, or conjunctival infection
  • First-line: doxycycline 100 mg PO bid for 7 days
    • Preferred, especially for rectal infection
  • Alternative if adherence likely to be poor: azithromycin 1 g PO once
  • Alternative: ofloxacin 300 mg PO bid for 7 days
  • Alternative: erythromycin 2 g/day PO in divided doses for 7 days
  • Alternative: erythromycin 1 g/day PO in divided doses for 14 days

Children

  • Consider child abuse when chlamydia is diagnosed in a prepubertal child
    • However, perinatal infection can persist for up to 3 years
  • ≤7 days old
    • Infants ≤2 kg: erythromycin 20 mg/kg/day PO in divided doses for 14+ days
    • Infants >2 kg: erythromycin 30 mg/kg/day PO in divided doses for 14+ days
  • 8 days to 1 month old: erythromycin 40 mg/kg/day PO in divided doses for 14+ days
  • 1 month to 9 years: azithromycin 12-15 mg/kg (max 1 g) PO once
    • Alternative: erythromycin 40 mg/kg/day PO in divided doses (max 500 mg qid for 7 days or 250 mg qid for 14 days)
    • Alternative: sulfamethoxazole 75 mg/kg/day PO in divided doses (max 1 g bid) for 10 days
  • 9-18 years: doxycycline 2.5 mg/kg (max 100 mg) PO bid for 7 days
    • Alternative, if adherence likely to be poor: azithromycin 12-15 mg/kg (max 1 g) PO once
    • Alternative: erythromycin 40 mg/kg/day PO in divided doses (max 500 mg qid for 7 days or 250 mg qid for 14 days)
    • Alternative: sulfamethoxazole 75 mg/kg/day PO in divided doses (max 1 g bid) for 10 days

Pregnant or Nursing Women

  • Pregnant and nursing women with urethral, endocervical, and rectal infections
  • Azithromycin is generally considered safe for this purpose, while doxycycline and fluoroquinolones are contraindicated
  • Options include any of:
    • Alternative: amoxicillin 500 mg PO tid for 7 days
    • Alternative: erythromycin 2 g/day PO in divided doses for 7 days
    • Alternative: erythromycin 1 g/day PO in divided doses for 14 days
    • Alternative if adherence is likely to be poor: azithromycin 1 g PO once
  • Ensure that exposed neonates are tested shortly after birth and treated if positive, with monitoring for development of conjunctivitis or pneumonia

Lymphogranuloma Venereum

Trachoma

  • Usually addressed in mass drug administration projects using azithromycin or topical tetracycline
  • Often needs surgery to correct trichiasis

Treatment Failure

  • Reinfection (most common)
  • Non-adherence
  • Vomiting
  • True resistance, though it is rare and difficult to assess susceptibility

Prevention

Trachoma

  • Mass drug administration using azithromycin for communities with high prevalence
  • Facial cleanliness
  • Improved sanitation and hygiene