Invasive Pasteurella multocida Infection With Cervical Abscess and Sternoclavicular Septic Arthritis Following a Cat Scratch in a Patient With Lymphedema: A Case Report.

Pasteurella multocida is a zoonotic pathogen transmitted through animal bites or scratches. Although most infections are localized, invasive disease may occur in vulnerable patients. An 86-year-old woman with metabolic syndrome and chronic right upper limb lymphedema developed fever and extensive inflammatory signs shortly after a superficial cat scratch. She had previously completed one course of amoxicillin with clavulanic acid and another of clindamycin without improvement. Blood cultures isolated Pasteurella multocida. Imaging revealed right upper-limb cellulitis, a cervical phlegmon, septic arthritis of the left sternoclavicular joint, a large anterior thoracic wall abscess and a posterior cervical abscess at the C4-C5 level. She received six weeks of intravenous ceftriaxone followed by six weeks of oral ciprofloxacin, with complete resolution. Minor animal-related injuries in patients with chronic lymphedema can evolve into severe invasive P. multocida infections. Early recognition, prompt imaging, and prolonged targeted antimicrobial therapy are essential when surgical drainage is not feasible or is associated with unacceptable risk.