Pathogen-targeted quick multiplex PCR identification of Chlamydia psittaci and Haemophilus influenzae coinfection in pneumonia: a case report

This study describes a rare case of pneumonia induced by coinfection with Chlamydia psittaci (C. psittaci) and Haemophilus influenzae (H. influenzae). The patient had a history of chronic nephritis and long-term pigeon breeding. The initial manifestation was slurred speech, followed by rapid progression to high fever and respiratory failure. Chest computed tomography revealed bilateral interstitial pneumonia, predominantly in the right lung. Pathogen-targeted quick multiplex polymerase chain reaction (pt-qPCR) confirmed the pathogens as C. psittaci and H. influenzae, and metagenomic next-generation sequencing (mNGS) further verified consistent results. After 7-days of combination therapy with doxycycline and azithromycin, the treatment was switched to doxycycline combined with moxifloxacin for an additional 8-days. The patient achieved complete recovery and was discharged from the hospital. This case suggests that pt-qPCR may facilitate early identification of mixed infections in patients with severe pneumonia and a history of avian exposure, thereby providing valuable information to guide clinical decision-making.