Recurrent Post-Pericardiectomy Mediastinal Collection Due to Pasteurella Multocida

Pasteurella multocida is a zoonotic gram-negative coccobacillus that usually causes skin and soft-tissue infection after animal bites; deep postoperative mediastinal infection is rare. A 53-year-old man with prior pericardiectomy presented 5 years later with fever, dyspnea, and chest pressure after a cat bite. Computed tomography showed an 11-cm loculated mediastinal collection near the prior surgical site. Percutaneous drainage yielded purulent fluid with marked neutrophilic leukocytosis, and culture grew P. multocida . Blood cultures and fungal studies were negative. He improved after drainage and 6 weeks of intravenous ertapenem, but later developed recurrent enlarging collections and a chest wall abscess requiring repeated drainage. Subsequent cultures were negative, likely reflecting partially treated relapse. He was transitioned to indefinite amoxicillin–clavulanate and remained asymptomatic at 1-year follow-up. This case highlights P. multocida as a rare cause of late postoperative mediastinal infection in which source control, prolonged therapy, and chronic suppression may be required.