High-Dose Tigecycline for the Treatment of Progressive Pneumonia Caused by Chlamydia psittaci: Case Series and Literature Review

Purpose: To summarize the clinical characteristics of progressive pneumonia caused by Chlamydia psittaci (C. psittaci) and to explore the effect of high-dose tigecycline on severe C psittaci.Patients and Methods: We retrospectively analyzed the clinical characteristics, treatment, and outcomes of three progressive pneumonia patients caused by C. psittaci in our hospital in the past three years.Results: All three patients showed high fever and progressive dyspnea, and all of them were finally diagnosed by bronchoalveolar lavage fluid (BALF) of metagenomic next-generation sequencing (mNGS). Case 1 rapidly developed into multilobar infiltration after raising a parrot with a normal appearance one week before. Respiratory failure occurred despite the use of moxifloxacin, requiring non-invasive ventilator-assisted ventilation. Case 2 developed discomfort one day after sightseeing in the forest park. Moxifloxacin was ineffective for her and she quickly developed respiratory failure, requiring invasive ventilator-assisted ventilation. Case 3 kept chickens and ducks at home. Respiratory failure and renal failure still occurred rapidly despite the use of doxycycline, requiring invasive ventilator-assisted ventilation and continuous renal replacement therapy (CRRT). After adjusting the antibiotic to high-dose tigecycline (100mg, I.V., q12h), all three patients were treated effectively and no side effects occurred.Conclusion: C. psittaci pneumonia is one of the causes of progressive pneumonia. High-dose tigecycline is safe and effective for the treatment of severe C. psittaci.