Overwhelming Sepsis due to Capnocytophaga canimorsus in an Immunocompetent Individual: A Rare Case Study

Abstract

We report this rare case of fatal fulminant sepsis in a 42-year-old African American female who presented with a three-day history of generalized pain and an evolving rash all over her body. On presentation, the patient was tachycardic, borderline hypotensive, and febrile. Physical examination was significant for diffuse petechiae and ecchymoses over the extremities, torso, and the face, especially confluent over her thighs and lower abdomen. She was admitted to the ICU, and initial investigations revealed a normal leukocyte count and hemoglobin but severe thrombocytopenia, elevated creatinine, blood urea nitrogen (BUN), bilirubin, transaminases, and an elevated INR. She also had a high anion gap metabolic acidosis with elevated lactate. Chest and abdomen CT findings were nonspecific, demonstrating fluid surrounding both kidneys, a moderate amount of fluid in the pelvis, and alveolar opacities at the bases of both lungs. Initial working diagnoses were a septic shock, thrombotic thrombocytopenic purpura (TTP), and vasculitis. She was initiated on broad-spectrum antibiotic coverage with vancomycin, piperacillin/tazobactam, and doxycycline pending culture reports. After a few hours, she became progressively hypothermic, developed disseminated intravascular coagulation (DIC) and hemodynamic instability, and was intubated due to acute hypoxic and hypercapnic respiratory failure. She progressively worsened hemodynamically with multi-organ dysfunction, and ultimately was pronounced dead roughly 18 hours after initial presentation. Blood cultures grew a Gram-negative organism, initially reported as Shewanella putrefaciens, but subsequently confirmed as Capnocytophaga canimorsus.

Keywords: capnocytophaga canimorsus; sepsis; shewanella putrefaciens; thrombotic thrombocytopenic purpura.

Figure 1. CT abdomen and pelvis without contrast: showing fluid surrounding both the kidneys with moderate amounts of fluid in the pelvis. Gall bladder showed a filling defect, thought to be secondary to sludge/calculus.