Clinical Characteristics of Six Patients with Chlamydia psittaci Infection Diagnosed by Metagenomic Next-Generation Sequencing: A Case Series

Abstract

The incidence of psittacosis infection has gradually increased in recent years. Metagenomic next-generation sequencing (mNGS) can be used to comprehensively identify the total DNA and RNA content of the microbiome, as well as identify both known and unexpected pathogens within 24 hours. We diagnosed and treated six patients with psittacosis infection using mNGS, two of whom developed severe disease and most of whom presented with pulmonary symptoms. One of the young female patients also presented with irregular vaginal bleeding and myocarditis. Patients with underlying gastric disorders first showed gastrointestinal symptoms, which is a rare manifestation in patients with psittacosis. Older patients with underlying disease usually showed more severe symptoms. However, rare complications can also occur in immunocompetent young people and develop into severe disease. All patients showed significant congestion at bronchial lumen lesions, which may be associated with a severe inflammatory response to mucosal Chlamydia psittaci ( C. psittaci ) infection. Overall, mNGS is a rapid and effective tool for the clinical diagnosis of psittacosis caused by C. psittaci , and early diagnosis and treatment can prevent psittacosis from developing into a serious illness.

Psittacosis: An Underappreciated and Often Undiagnosed Disease

“…Similar to PCR, metagenomic data from next generation sequencing (mNGS) has higher sensitivity and is faster than culture [ 53 ]. Metagenomics data has successfully been used to identify C. psittaci cases within 24 h [ 78 ]. Given the potential ability to find evidence of C. psittaci infection from NGS versus a negative serological test, NGS use has been referred to as ‘hypothesis-free pathogen detection’ [ 79 ].…”

Chlamydia psittaci Pneumonia: Diagnosis, Treatment, and Challenges in the Context of COVID-19

“…The clinical features of Chlamydia psittaci infection are generally nonspecific. However, there have been reports of yellow-white sputum production in a minority of cases of Chlamydia psittaci pneumonia [ 3 – 5 ]. Research has demonstrated that the color of sputum can serve as a significant predictor of potentially pathogenic microorganisms.…”

Whole genome sequencing characteristics of Chlamydia psittaci caprine AMK-16 strain, a promising killed whole cell veterinary vaccine candidate against chlamydia infection

“…Initially, these bacteria were associated with only avian psittacosis [4][5][6]. However, since then it has been clearly proven that C. psittaci is also responsible for airway inflammation and reproductive disorders in cattle, small ruminants, domestic animals and humans [7][8][9][10][11][12][13]. C. psittaci (ovis), which is now re-classified to Chlamydia abortus, is responsible for abortion, stillbirth or fetal loss in ruminants worldwide.…”

“…However, since then it has been clearly proven that C . psittaci is also responsible for airway inflammation and reproductive disorders in cattle, small ruminants, domestic animals and humans [ 7 – 13 ]. C .…”