Clinical Analysis of Metagenomic Next-Generation Sequencing Confirmed Chlamydia Psittaci Pneumonia: A Case Series and Literature Review

Introduction Chlamydia psittaci infection is a zoonotic infectious disease, which mainly inhaled through the lungs when exposed to the secretions of poultry that carry pathogenic bacteria. The traditional respiratory specimens or serological antibody testing is slow, and the false-negative rate is high. Metagenomic next-generation sequencing (mNGS) gives a promising rapid diagnosis tool. Methods We retrospectively summarized the clinical characteristics of five C. psittaci pneumonia patients diagnosed by mNGS, conducted a literature review summarizing the clinical characteristics of patients with C. psittaci pneumonia reported since 2010. Results Five C. psittaci pneumonia patients confirmed by mNGS aged from 36 to 66 years with three males. About 60% of patients had a history of contact with avian or poultry. All patients had a high fever over 38.5 °C, cough, hypodynamia, hypoxemia, and dyspnea on admission. Two patients had invasive ventilator support and extracorporeal membrane oxygenation support. Inflammatory index levels on admission and follow-up were all higher than normal values. Doxycycline or moxifloxacin and their combination therapy were used in patients. Four patients improved and were discharged, and one patient died due to multiple organ failures and disseminated intravascular coagulation. We summarized 19 articles including 69 C. psittaci pneumonia patients and patients in 11 publications were identified by mNGS, and most patients are treated with tetracycline and quinolone with good outcomes. Conclusion mNGS is a promising rapid diagnosis tool, which may increase the detection rate and shorten the diagnosis time of C. psittaci pneumonia. Further case-control studies are needed to confirm.