The application of metagenomic next-generation sequencing in diagnosing Chlamydia psittaci pneumonia: a report of five cases

BACKGROUND: Chlamydia psittaci pneumonia is a zoonotic infectious disease caused by Chlamydia psittaci. Diagnostic tools, including culture, serologic test and PCR-based methods, are available but prone to false negative results. CASE PRESENTATION: This report included five cases of Chlamydia psittaci pneumonia. Symptoms and signs common to all 5 cases included fever, coughing, generalized muscle ache, and most notably, inflammatory infiltration of the lungs upon chest CT and X-ray. Metagenomic next-generation sequencing (mNGS) revealed the presence of Chlamydia psittaci in biopsy lung tissue in 3 cases and bronchoalveolar lavage fluid in the remaining 2 cases. Three patients responded to doxycycline plus moxifloxacin; two patients responded to moxifloxacin alone. CONCLUSIONS: mNGS could be used to diagnose Chlamydia psittaci pneumonia.