AUTHOR=Liang Yueming , Dong Tingyan , Li Minjing , Zhang Peifang , Wei Xiaoqun , Chen Haitao , Wang Yongsi , Gao Xinglin 

TITLE=Clinical diagnosis and etiology of patients with Chlamydia psittaci pneumonia based on metagenomic next-generation sequencing

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.1006117

DOI=10.3389/fcimb.2022.1006117

ISSN=2235-2988

ABSTRACT=<p>The incidence of severe <italic>Chlamydia psittaci</italic> (<italic>C. psittaci</italic>) pneumonia and coinfections is increasing. Early detection of this condition is needed to prevent negative outcomes, along with detailed descriptions of its associated clinical characteristics. Our study contributes by undertaking etiological analysis of patients with <italic>C</italic>. <italic>psittaci</italic> pneumonia based on metagenomic next-generation sequencing (mNGS). A retrospective analysis of 30 patients with <italic>C. psittaci</italic> pneumonia was undertaken and confirmed by mNGS or polymerase chain reaction (PCR). Clinical manifestations of the severe and non-severe <italic>C. psittaci</italic> pneumonia groups were compared for clinical reference. Etiological analyses were also performed to comprehensively understand pathogeny and coinfection with other respiratory pathogens in <italic>C. psittaci</italic> patients. The absolute value of lymphocytes (LYM) in the severe group was lower than in the non-severe group. At the same time, neutrophil-to-lymphocyte ratio (NLR), procalcitonin (PCT), alanine aminotransferase (ALT), D-II polymer, brain natriuretic peptide (BNP), myoglobin (MYO), and cardiac troponin I (cTnI) were significantly higher (<italic>P</italic> &lt; 0.05) in the severe group. mNGS has a broader pathogen spectrum and can more sensitively detect <italic>C. psittaci</italic> and other low-abundance pathogens with a higher positive detection rate (100%, 13/13 vs. 46%, 6/13, <italic>P &lt;</italic>0.05) than conventional culture methods. mNGS detected the following dominant species associated with <italic>C. psittaci</italic> in patients: bacteria (53.2%, 39% gram-positive, 61% gram-negative), fungi (12.9%), and viruses (33.9%). A total of 73.3% (11/15) of patients had suspected coinfections, with a coinfection rate of 91.7% (11/12) in the severe group. No coinfection or death occurred in the non-severe group. Prognosis in the severe group was poor, with a mortality rate of 27.3% (3/11) for patients with coinfection. Eight of 11 patients with coinfections (72.7%) recovered. In conclusion, the clinical symptoms of severe <italic>C. psittaci</italic> pneumonia manifested as abnormal inflammatory indicators, impaired liver function, myocardial injury, coagulation, and relatively low immune responses. The higher proportion of patients with coinfections in our study supports the use of mNGS for comprehensive early detection of respiratory infections in patients with <italic>C. psittaci</italic> pneumonia. Simultaneous early identification of coinfections would further improve the clinical treatment of these patients.</p>