PLE-3482

A 21-year-old female complains of fever, crampy abdominal pain with voluminous stools occasionally being grossly bloody. Lab tests were done, which showed the following: Gram stain revealed gram-negative rods, catalase and oxidase positive. Growth in broth showed that the bacteria were mostly found near the top but not at the topmost, and optimal growth was at 42 °C. What is the most likely organism isolated?