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 <i>P. multocida</i> infections. Early recognition, prompt imaging, and prolonged targeted antimicrobial therapy are essential when surgical drainage is not feasible or is associated with unacceptable risk.