Chlamydial Infections

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.

⭐ 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.

⭐ 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.
• 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).