191.1 🎓 醫孞生版

191.1.0.1 📌 䞀頁重點

  • Chlamydophila pneumoniae (formerly Chlamydia):
    • Atypical CAP cause (5-10% adults)
    • Person-to-person respiratory transmission
    • Acute (pharyngitis, bronchitis, pneumonia)
    • Chronic association: atherosclerosis (controversial), asthma exacerbation, COPD, multiple sclerosis (proposed)
    • Macrolide / doxycycline / FQ
  • Chlamydophila psittaci (psittacosis):
    • Bird-borne (parrots, parakeets, pigeons, poultry — droppings/aerosol)
    • Severe atypical pneumonia + hepatosplenomegaly + bradycardia (Faget sign — like typhoid)
    • Headache severe, can be confused with typhoid
    • Doxycycline 100 bid × 14-21d
    • 通報 (notifiable, bird-related occupational)
  • Treatment:
    • Both: doxycycline 100 mg PO bid × 14d
    • Alt: azithromycin, levofloxacin
    • β-lactams 䞍 effective (no cell wall like all Chlamydia)
  • Dx:
    • PCR of nasopharyngeal swab / sputum / BAL
    • Serology (paired) — IgM, IgG
    • C. psittaci: occupational / pet bird history is key — ask explicitly

191.1.0.2 1⃣ 现菌孞

  • Both obligate intracellular gram -
  • EB / RB biphasic lifecycle (same as C. trachomatis Ch 190)
  • No cell wall → β-lactam useless
  • DNA-based reclassification: C. pneumoniae and C. psittaci → genus Chlamydophila (some taxonomy still uses Chlamydia)

191.1.0.3 2⃣ Chlamydophila pneumoniae

191.1.0.3.1 流行病孞
  • Ubiquitous globally; person-to-person respiratory
  • Most acquired in childhood (most people serologically + by adulthood)
  • Reinfection common (waning immunity)
  • ~ 5-10% of adult CAP
  • Often co-infection with other respiratory pathogens
  • Cycles every 4-7 yr (outbreaks in close-contact populations)
191.1.0.3.2 Acute Clinical
191.1.0.3.2.1 Pharyngitis / Bronchitis
  • 兒童 + young adult
  • Often mild and self-limited
191.1.0.3.2.2 Pneumonia
  • Atypical: gradual onset, dry cough, low-grade fever, mild
  • CXR: reticulonodular, often unilateral
  • Similar presentation to M. pneumoniae
  • More common in 老幎, COPD, immunocompromise — can be severe
191.1.0.3.2.3 Bilateral pneumonia, multi-lobar
  • Severe in elderly / debilitated
191.1.0.3.3 Chronic Associations (Controversial)
  • Atherosclerosis — IgG seroprevalence higher in CAD vs control; prospective antibiotic trials negative (azithro / clari did NOT reduce events) → mechanism uncertain
  • Asthma exacerbation — some studies support; current guidelines don’t routinely treat
  • COPD exacerbation
  • Multiple sclerosis — proposed (Stratton et al, 2002+) but not confirmed
  • Stroke, dementia — proposed
  • Most experts: not causative; co-existing or marker of inflammation
191.1.0.3.4 Treatment
  • Doxycycline 100 mg PO bid × 14d OR
  • Azithromycin 500 mg day 1 → 250 mg qd × 4d OR
  • Clarithromycin 500 mg PO bid × 14d
  • Levofloxacin 500-750 mg qd × 7-14d
  • 同 macrolide R issues as M. pneumoniae (rising)
  • Pediatric: macrolide preferred
191.1.0.3.5 Diagnosis
  • PCR of NP / sputum / BAL (best)
  • Multiplex panels (BioFire) often include
  • Serology paired (acute + convalescent 2-3 wk)
  • Difficult to distinguish from other atypicals clinically

191.1.0.4 3⃣ Chlamydophila psittaci (Psittacosis / Ornithosis)

191.1.0.4.1 Microbiology + Reservoir
  • C. psittaci
  • Birds primary reservoir: parrots, parakeets, cockatoos, lovebirds (highest risk), but also pigeons, turkeys, ducks, poultry workers
  • Cats — feline keratoconjunctivitis
191.1.0.4.2 Transmission
  • Aerosolized droppings / respiratory secretions of infected birds
  • Inhalation of dried fecal material is main route
  • Direct contact / bird bite (less common)
  • Person-to-person rare but reported in outbreaks
  • Ranges from asymptomatic carrier birds to clinically ill birds (puffed feathers, diarrhea, lethargy)
191.1.0.4.3 流行病孞
  • Occupational: bird workers, vets, pet shop, poultry processors
  • Pet exposure: parrot, parakeet at home
  • Outbreaks: pet stores, poultry plants, zoological collections
  • 通報 (notifiable, especially with cluster)
191.1.0.4.4 Clinical
  • Incubation 5-14 d
  • Acute onset: 高 fever (≥ 39°C), severe headache (often presenting symptom), myalgia
  • Pneumonia: dry / non-productive cough, dyspnea
  • Hepatosplenomegaly in 30%
  • Faget sign (relative bradycardia) — like typhoid
  • Sometimes confused with typhoid fever
  • Severe: ARDS, multi-organ failure
  • “Horder’s spots” — pink macular rash, rare
191.1.0.4.5 Complications
  • ARDS
  • Endocarditis (rare)
  • Myocarditis, pericarditis
  • Hepatitis
  • Encephalitis (rare)
191.1.0.4.6 Imaging
  • CXR: patchy consolidation, unilateral typical
  • Hilar LAP
191.1.0.4.7 Lab
  • ↑ LFT, ↑ CRP, ↑ ESR
  • Mild leukopenia
  • Hyponatremia
  • Thrombocytopenia
  • Anemia possible
191.1.0.4.8 Diagnosis
  • PCR of NP / sputum (BSL-3 — careful, infectious to lab workers)
  • Serology paired IgM/IgG (limited availability)
  • Bird exposure history is KEY — ask explicitly
  • Imaging compatible
191.1.0.4.9 Treatment
  • Doxycycline 100 mg PO bid × 14-21d (preferred)
  • Tetracycline alt
  • Macrolide (azithromycin) — less data, alt
  • Pregnancy: azithromycin
191.1.0.4.10 Bird Source Investigation
  • Public health collaboration
  • Pet birds tested + treated (chlortetracycline in food)
  • Bird-related occupations notified
  • Outbreak: source identification + treatment of human contacts

191.1.0.5 4⃣ Diagnosis Both Species

191.1.0.5.1 PCR (Multiplex Respiratory Panels)
  • BioFire FilmArray, Luminex, etc.
  • Fast (1-2 hr)
  • Species-specific
  • Most sensitive
191.1.0.5.2 Serology
  • Paired sera 2-3 wk apart
  • 4-fold rise (limited utility for acute decision)
  • Microimmunofluorescence (MIF) gold standard but specialized labs
  • ELISA also available
191.1.0.5.3 Culture
  • BSL-3 — only specialty labs; not routine
191.1.0.5.4 Tissue / BAL
  • Severe cases: BAL with PCR

191.1.0.6 5⃣ Treatment Summary

Drug C. pneumoniae C. psittaci
Doxycycline 100 bid × 14d First-line First-line × 14-21d
Azithromycin Alt Alt (pregnancy)
Clarithromycin Alt Alt
Levofloxacin / Moxifloxacin Alt Alt
β-lactam No effect No effect