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

• Incubation period is 2 to 3 weeks (Incubation period range::1 to 6 weeks)
• Many are asymptomatic
• Presentation varies by serovar

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

Sexually-Transmitted Infection

• In men, most are symptomatic
  • Incubation period is 7 to 21 days in men
  • Purulent urethritis, urethral itch, dysuria, testicular pain
  • Conjunctivitis
  • Proctitis (often asymptomatic)
  • Sequelae include epididymo-orchitis and reactive arthritis
• In women, often asymptomatic
  • Cervicitis, vaginal discharge, dysuria, lower abdominal pain, abnormal vaginal bleeding, dyspareunia
  • Conjunctivitis
  • Proctitis (often asymptomatic)
  • Sequelae include pelvic inflammatory disease, ectopic pregnancy, infertility, chronic pelvic pain, and reactive arthritis

Lymphogranuloma Venereum

• See lymphogranuloma venereum

Fitz-Hugh-Curtis syndrome

• Liver capsular inflammation, possibly autoimmune

Pediatric Infections

• Conjunctivitis in neonates
• Pneumonia in children under 6 months of age

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
• Serology
  • IgM antibodies can be helpful for diagnosting pneumonia in infants under 3 months of age
  • Not helpful for diagnosing genital infections

Management

• Non-pregnant, non-lactating adults with urethral, endocervical, rectal, or conjunctival infection
  • First-line: doxycycline 100 mg PO bid for 7 days
  • 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 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: doxycycline 100 mg PO bid for 21 days (see LGV-specific page for details)