Application of metagenomic next-generation sequencing in the diagnosis of severe pneumonia caused by Chlamydia psittaci

Abstract

Purpose Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci (C. psittaci) from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases are treated without diagnostic testing, and the importance of Chlamydia psittaci infection as a cause of CAP is therefore unclear. Diagnostic tools, including culture, serologic test, and PCR-based methods, are available but prone to false negative results. Metagenomic next-generation sequencing (mNGS) has been increasingly used in the diagnosis of infectious diseases, particularly when conventional diagnostic approaches have limitation. Detection of nucleic acid sequence of C. psittaci in respiratory tract samples by metagenomic next-generation sequencing (mNGS) is effective for early diagnosis of severe C. psittaci pneumonia. Timely treatment based on tetracycline can reduce unnecessary use of antibiotics and improve prognosis of patients with severe C. psittaci pneumonia. Methods Clinical data of thirteen patients with severe C. psittaci pneumonia diagnosed by mNGS were collected. Clinical manifestations, treatment and prognosis of patients were summarized. Results The typical symptoms of pneumonia caused by C. psittaci include fever, headache, myalgia, cough, and dyspnea. In the current study, all patients met the criteria for severe C. psittaci pneumonia and received mechanical ventilation, including noninvasive mechanical ventilation (five/thirteen) and invasive mechanical ventilation (eight/thirteen). The findings showed that patients with C. psittaci pneumonia presented with normal or slightly increased leucocytes and procalcitonin, and high C-reactive protein levels. Computed tomography manifestations included consolidation of lung parenchyma, with air bronchogram and pleural effusion in some patients. mNGS analysis results were obtained within 48–72 h. Eleven patients fully recovered after targeted treatment, however, two patients died from secondary multidrug-resistant Pseudomonas aeruginosa infection. Conclusions The findings of the current study show that mNGS is effective in diagnosis of C. psittaci pneumonia, and has significant diagnosis value in patients with severe infection. Patients responds well to the timely use of appropriate antibiotics.

Clinical, radiological and pathological characteristics of moderate to fulminant psittacosis pneumonia

“…Increased pH values and reduced PaCO2 and PaO2 may be associated with fever, increased RR, and severe pneumonia. Increased NE ratio, CRP, ESR, and PCT levels were discovered in most of patients, consistent with the previous study [ 17 , 18 ], suggesting these inflammatory biomarkers may contribute to assessing the infection of C . psittaci .…”

A Case of Chlamydia Psittacosis with Severe Pneumonia Combined with Acute Hepatitis B and Literature Review

“…The mortality rate of Chlamydia psittaci infection in foreign countries is less than 1% (Macfarlane JT & Macrae AD., 1983). However, two recent retrospective studies in our country showed that 4 out of 27 patients died due to secondary infection (Yang F, Li J, Qi B & et al, 2021), and 2 out of 13 patients died (Wu HH, Feng LF & Fang SY., 2021). In some other countries, psittacosis is a notifiable disease and must be reported within 48 hours (DE Boeck C, Dehollogne C, Dumont A & et al, 2016).…”

Tigecycline in the treatment of severe pneumonia caused by Chlamydia psittaci: A case report and literature review

“…Wen et al ( 28 ) reported a case of severe C. psittaci pneumonia in which tigecycline was used for treatment, but the treatment effect was not described in detail. Wu et al ( 29 ) reported that three patients received carbapenems, linezolid, or tigecycline in addition to doxycycline treatment after diagnosis, but the outcomes were not stated. Kong et al ( 30 ) reported that two patients with severe C. psittaci pneumonia were not effective in initial treatment with moxifloxacin and were improved after using tigecycline.…”