Chlamydia Infections

🦠 Chlamydial Infections are caused by Chlamydia trachomatis, C. pneumoniae, and C. psittaci. They are obligate intracellular bacteria and can affect the genital tract, respiratory tract, eyes, and lymphatics. 💡 Remember: Chlamydia is the most common bacterial STI in the UK - often silent but with serious long-term complications if untreated.

🚻 Genital Chlamydia (C. trachomatis)

• Most common bacterial STI; often asymptomatic (70% women, 50% men).
• Women: dysuria, vaginal discharge, pelvic pain, post-coital bleeding.
• Men: urethral discharge, epididymo-orchitis, dysuria.
• Complications: PID, ectopic pregnancy, infertility, Fitz-Hugh–Curtis syndrome.
• Diagnosis: NAAT on urine (men) or vaginal/cervical swab (women); rectal/pharyngeal swabs if relevant.
• Treatment: Doxycycline 100 mg BD × 7 days (first-line). Alternative: Azithromycin 1 g stat (esp. in pregnancy). Treat partners, screen for other STIs, retest in 3 months.

🫁 Chlamydia Pneumoniae

• Causes pharyngitis, bronchitis, sinusitis, or atypical pneumonia (“walking pneumonia”).
• Features: cough, sore throat, fatigue, fever; severe pneumonia in elderly or immunocompromised.
• Diagnosis: PCR/serology; CXR may show patchy interstitial infiltrates.
• Treatment: Doxycycline or azithromycin. Alternatives: clarithromycin, levofloxacin.

👁️ Adult Inclusion Conjunctivitis

• Due to C. trachomatis; autoinoculation from genital secretions.
• Unilateral red, gritty eye with mucopurulent discharge.
• Diagnosis: NAAT or PCR on conjunctival swab.
• Treatment: Oral doxycycline/azithromycin for 7–14 days. Topical erythromycin as adjunct. Treat partners, avoid contact lenses during therapy.

👶 Neonatal Conjunctivitis (Ophthalmia Neonatorum)

• Acquired during vaginal delivery from infected mother.
• Onset 5–14 days postpartum: red swollen eyelids, purulent discharge.
• Can be associated with neonatal pneumonia (staccato cough).
• Diagnosis: Conjunctival swab (NAAT/culture); CXR if pneumonia suspected.
• Treatment: Oral erythromycin for neonate; treat mother + partner.

🌐 Lymphogranuloma Venereum (LGV)

• Caused by invasive L1–L3 serovars of C. trachomatis.
• Stage 1: painless genital ulcer. Stage 2: painful inguinal lymphadenopathy (buboes). Rectal LGV: proctitis, discharge, tenesmus (esp. MSM).
• Diagnosis: NAAT; PCR for LGV-specific strains.
• Treatment: Doxycycline 100 mg BD × 21 days. Drain buboes if necessary. Partner treatment essential.

👁️🌍 Trachoma

• Repeated infection with C. trachomatis serovars A–C. Leading infectious cause of blindness worldwide.
• Scarring of eyelid → entropion → corneal damage.
• Diagnosis: Clinical (WHO grading); PCR in epidemiology.
• Treatment (WHO SAFE strategy): S = Surgery for trichiasis. A = Azithromycin mass treatment. F = Facial cleanliness. E = Environmental improvement.

🐦 Chlamydia Psittaci (Psittacosis)

• Zoonotic infection from birds (parrots, pigeons, poultry).
• Features: atypical pneumonia, fever, dry cough, hepatosplenomegaly.
• Diagnosis: Serology or PCR on respiratory samples; CXR shows patchy consolidation.
• Treatment: Doxycycline (drug of choice). Alternatives: macrolides. Notify public health if outbreak suspected.

📝 Teaching Pearls

💡 Exam tips:
- Genital chlamydia is often silent → screen at-risk groups. - Red eye + genital symptoms → think chlamydial conjunctivitis. - MSM with proctitis + inguinal buboes → consider LGV. - Trachoma remains a huge cause of blindness in low-resource countries. - Always treat the patient + partner, and arrange full STI screen.