The application of metagenomic next-generation sequencing in diagnosing Chlamydia psittaci pneumonia: a report of five cases

Abstract

Background: Chlamydia psittaci pneumonia is a zoonotic infectious disease caused by Chlamydia psittaci. Diagnostic tools, including culture, serologic test and PCR-based methods, are available but prone to false negative results.

Case presentation: This report included five cases of Chlamydia psittaci pneumonia. Symptoms and signs common to all 5 cases included fever, coughing, generalized muscle ache, and most notably, inflammatory infiltration of the lungs upon chest CT and X-ray. Metagenomic next-generation sequencing (mNGS) revealed the presence of Chlamydia psittaci in biopsy lung tissue in 3 cases and bronchoalveolar lavage fluid in the remaining 2 cases. Three patients responded to doxycycline plus moxifloxacin; two patients responded to moxifloxacin alone.

Conclusions: mNGS could be used to diagnose Chlamydia psittaci pneumonia.

Keywords: Case report; Chlamydia psittaci; mNGS.

Fig. 1

Chest CT and X-ray of case 1: a, b On the day of admission, c, d 21 days after doxycycline treatment, and e Chest X ray of patient’s pet dog

Fig. 2

Chest CT of case 2: a On the 4th day of the onset, b On the 4th day of arrival to our hospital, c 7 days after treatment with doxycycline plus moxifloxacin, and d 3 weeks later after treatment with doxycycline plus moxifloxacin

Fig. 3

Chest CT of case 3: a, b On the day of admission, c, d 9 days after treatment with doxycycline plus moxifloxacin

Fig. 4

Chest CT of case 4: a, b On the day of admission, c Eight days after treatment with moxifloxacin, and dSixteen days after discontinuation

Fig. 5

Chest CT of case 5: a, b, c On the day of admission, d, e, f Eight days after treatment with moxifloxacin