Chlamydial Infections

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Chlamydial Infections - The Obligate Intruder

  • Obligate intracellular bacteria; energy parasites (cannot synthesize ATP). Poorly Gram-staining.
  • Chlamydia trachomatis is the most common species.
    • Serovars A, B, Ba, C: Trachoma (chronic keratoconjunctivitis).
    • Serovars D-K: Urogenital infections (urethritis, cervicitis, PID), neonatal conjunctivitis, infant pneumonia.
    • Serovars L1, L2, L3: Lymphogranuloma Venereum (LGV).
  • Unique biphasic lifecycle:
    • Elementary Body (EB): Small, dense, infectious, extracellular. Metabolically inert. 📌 Elementary = Enters cell.
    • Reticulate Body (RB): Larger, metabolically active, replicative, intracellular. 📌 Reticulate = Replicates. Chlamydia trachomatis lifecycle diagram

C. trachomatis lacks a typical peptidoglycan layer but possesses penicillin-binding proteins (PBPs), rendering it susceptible to certain β-lactam antibiotics despite its "atypical" nature.

Chlamydial Infections - Silent Spread & Sequelae

  • Chlamydia trachomatis: Obligate intracellular; often asymptomatic, enabling silent spread and delayed diagnosis.
  • Urogenital Manifestations:
    • Males: Urethritis (mucoid discharge), epididymitis.
    • Females: Cervicitis, Pelvic Inflammatory Disease (PID); frequently subclinical, risking severe sequelae.
  • Neonatal:
    • Conjunctivitis: 5-14 days post-birth; mucopurulent.
    • Pneumonia: Afebrile, staccato cough; 4-12 weeks post-birth.
  • Key Sequelae:
    • PID leads to: Infertility, ectopic pregnancy, chronic pelvic pain.
    • Reactive Arthritis (Reiter's): Urethritis, arthritis, conjunctivitis. 📌 "Can't see, can't pee, can't climb a tree."
    • Lymphogranuloma Venereum (LGV): Serovars L1-L3. Chlamydia trachomatis clinical manifestations

⭐ Up to 40% of untreated chlamydial infections in women progress to Pelvic Inflammatory Disease (PID), a leading cause of preventable infertility.

Chlamydial Infections - Beyond the Belt

  • Lymphogranuloma Venereum (LGV): C. trachomatis L1-L3.
    • Primary: Evanescent ulcer. Secondary: Painful inguinal buboes.
    • Tertiary: Genital elephantiasis, strictures.
    • Rx: Doxycycline 100mg BD for 21 days.
  • Trachoma: C. trachomatis A-C.
    • Leading preventable infectious blindness.
    • Signs: Follicles, Arlt's line (scarring), trichiasis, corneal opacity.
    • 📌 SAFE strategy: Surgery, Antibiotics, Facial cleanliness, Environmental hygiene. Trachoma: Arlt's line and Herbert's pits
  • Reactive Arthritis (Reiter's Syndrome):
    • Aseptic arthritis post-Chlamydia.
    • 📌 Triad: Conjunctivitis/uveitis, urethritis, arthritis.
    • HLA-B27 associated.

⭐ The "Groove sign" in LGV is pathognomonic, formed by inguinal ligament separating inflamed lymph node groups.

Chlamydial Infections - Detective Work & Takedown

  • Diagnosis (Dx):
    • Gold Standard: Nucleic Acid Amplification Tests (NAATs).
    • Samples: First-catch urine (men), endocervical/vaginal swabs (women). Rectal/pharyngeal swabs if indicated.
  • Management (Rx):
    • Uncomplicated Genital Chlamydia:
      • Azithromycin 1g single dose OR
      • Doxycycline 100mg BD for 7 days.
    • Partner Management: Treat all sexual partners from the last 60 days. Expedited Partner Therapy (EPT) if available.
    • Screening: Annually for sexually active women <25 yrs & older women with risk factors. MSM at least annually.
    • Test of Cure: Not routinely needed; consider in pregnancy (3-4 wks post-Rx).

⭐ Chlamydia trachomatis is a leading cause of preventable blindness (trachoma) and reactive arthritis (Reiter's syndrome).

High-Yield Points - ⚡ Biggest Takeaways

  • Most common bacterial STI; C. trachomatis serovars D-K (urogenital), L1-L3 (LGV).
  • Frequently asymptomatic, especially in women, risking PID, infertility, ectopic pregnancy.
  • Males: Non-gonococcal urethritis (NGU), epididymitis.
  • Neonates: Inclusion conjunctivitis, afebrile pneumonia.
  • NAAT (e.g., PCR) is the gold standard for diagnosis.
  • Treatment: Azithromycin (1g single dose) or Doxycycline (100mg BD, 7 days).
  • Associated with Reactive Arthritis (Reiter's syndrome).
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