Co-Infection of Chlamydia psittaci and Methicillin-Resistant Staphylococcus aureus in Community-Acquired Pneumonia - A Case Report

This study presents a rare case of community-acquired pneumonia (CAP) caused by a co-infection of Chlamydia psittaci and Methicillin-resistant Staphylococcus aureus (MRSA), confirmed by targeted next-generation sequencing (tNGS). The patient had a history of diabetes mellitus and hypertension. He developed fever, fatigue, myalgia and poor appetite two days before admission. He had watched someone slaughter a chicken two days prior to the onset of symptoms. The chest CT revealed consolidative changes. We suspected that the patient might have Chlamydia psittaci infection. Given the low sensitivity and time-consuming nature of conventional microbial culture, tNGS was utilized in this case to improve diagnostic accuracy and reduce detection time. Targeted next-generation sequencing (tNGS) identified a co-infection with Chlamydia psittaci and methicillin-resistant Staphylococcus aureus (MRSA). Recovery was achieved after treatment with omadacycline and linezolid. The Chlamydia psittaci was likely transmitted from the chicken, and the patient’s diabetes mellitus increased susceptibility to MRSA. This case highlights the risk of polymicrobial infections in diabetic individuals and the diagnostic value of tNGS.