Clinical Characteristics of Chlamydia psittaci Pneumonia Infection in Central South China

Chlamydia psittaci pneumonia has been a global public health hotspot in recent years. Although some scattered cases of C. psittaci pneumonia have been reported, there is a lack of large case studies worldwide.

In this multicenter, observational study, we recruited all consecutive patients with confirmed C. psittaci pneumonia from October 4, 2018, to October 23, 2020, in nine tertiary general hospitals in Central-South China. Epidemiologic and clinical data from patients' electronic medical records were collected and analyzed.

One hundred and sixteen patients with C. psittaci pneumonia were included in the study. The mean age was 59.7 years. Fever (96.6%) and cough (65.5%) were the most common clinical symptoms. Most patients presented with an increase in the proportion of neutrophils, neutrophil to lymphocyte ratio, LDH, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and a significant decrease in lymphocytes. The main CT lung findings were consolidation (81%) and pleural effusion (35.3%), and bilateral lung consolidation was mainly found in severe patients. Chlamydia psittaci DNA was detected in BALF (bronchoalveolar lavage fluid) or blood samples by metagenomic next-generation sequencing (mNGS) in all patients. Use of quinolone was associated with shorter length of hospital stay and fever duration after antibiotic use. Multivariate logistic regression analysis indicated that respiratory support was associated with both severe pneumonia and in-hospital death.

The clinical phenotype of C. psittaci pneumonia is complex and variable. mNGS is helpful in the diagnosis and treatment of C. psittaci pneumonia, and early treatment with quinolone may benefit patients.