An 87-year-old man had been treated with piperacillin (PIPC) for pneumonia at the previous hospital. He was admitted to our hospital because of massive pleural effusion in the left hemithorax with disturbance of consciousness. On admission, he was comatose (III-200 on the Japan Coma Scale). Chest radiograph and computed tomography (CT) showed a massive left pleural effusion with a mediastinal shift to the right. He was diagnosed with empyema due to white pleural effusion with a foul odor. The pleural effusion pH was 7.57, indicating that it was alkaline. A chest drain was placed, and the antibiotic was changed to ampicillin/sulbactam. Blood tests showed an increased ammonia level of 373μg/dL with normal liver function. On the third day, the blood ammonia level had decreased to 29μg/dL, and his consciousness levels improved. α-Streptococcus was detected from the pleural culture.
Cases of hyperammonemia with consciousness disturbance due to urinary tract infection are occasionally reported, but those due to empyema are rare.