Clinical Characteristics of Chlamydia psittaci Pneumonia Confirmed by Metagenomic Next-Generation Sequencing

Chlamydia psittaci pneumonia has atypical clinical manifestations and the diagnosis may be missed by traditional methods of microbiological diagnosis.

Twelve cases of Chlamydia psittaci pneumonia diagnosed by metagenomic next-generation sequencing (mNGS) in Huizhou Central People's Hospital in China between January 2020 and August 2021 were reviewed and analyzed, retrospectively, using hospital records, the clinical characteristics, treatment, and prognosis.

Ten of the 12 cases (83%) were associated with a definite history of bird/poultry contact. Common symptoms included high fever, cough, fatigue, anorexia (12/12, 100%), dyspnea (11/12, 92%), and changes in the level of consciousness and headache (5/12, 42%). There was a marked increase in C-reactive protein and D-dimer levels, but white blood cells and neutrophils were normal or slightly increased. Nine patients (75%) had liver enzyme abnormalities, and six (50%) had cardiac insufficiency and myocardial injury. There was no correlation between the mNGS sequence number of Chlamydia psittaci and the pneumonia severity. The chest imaging manifestations were mainly large areas of consolidation, predominantly in the lower lung lobes. Monotherapies or combinations of doxycycline, moxifloxacin/levofloxacin, and azithromycin were effective for treating Chlamydia psittaci pneumonia.

The use of mNGS increases the probability of diagnosing Chlamydia psittaci pneumonia, and good prognosis can be achieved with timely use of appropriate antibiotics.