Chlamydia psittaci Pneumonia Complicated with Lower Extremity Atherosclerotic Occlusive Disease

Chlamydia is a zoonotic pathogen that mainly infects poultry and pet birds. This Gram-negative obligate intracellular parasite also causes human psittacosis, the severity of which varies from mild flu-like symptoms to life-threatening severe pneumonia, including sepsis, acute respiratory distress syndrome, and multiple organ failure. Inhalation of aerosols from contaminated bird excreta through the respiratory tract is the main route of transmission to humans. Here, we present a case of Chlamydia psittaci pneumonia accompanied by lower extremity atherosclerotic occlusive disease. A 48-year-old man was admitted to the emergency department with a four-day history of cough and dyspnea. A detailed history revealed his contact with domestic pigeons. The results of metagenomic next-generation sequencing of bronchoalveolar lavage fluid suggested C. psittaci infection. Antibacterial agents were switched to targeted doxycycline, but in the next week, skin examination revealed acrocyanosis of both lower extremities, and the remarkable palpable purpura progressively worsened. Re-examination of the lower extremity vascular ultrasound suggested left dorsalis pedis artery occlusion and right peroneal vein thrombosis, which resulted in the amputation of both legs. This case is the first report of C. psittaci pneumonia combined with arterioocclusive sclerosis of both lower extremities.