Campylobacter and Helicobacter pylori

All of the following are characteristic features of Campylobacter jejuni EXCEPT:

A 42-year-old woman from Delhi presents with a 6-month history of recurrent epigastric pain, early satiety, and occasional hematemesis. Upper endoscopy reveals a gastric ulcer with a clean base. Rapid urease test on antral biopsy is positive. Which of the following best describes the pathogenic mechanism and the rationale for triple therapy in this patient?

A 28-year-old man from rural India presents with acute diarrhea, abdominal cramps, and fever for 3 days following consumption of undercooked chicken. Stool culture reveals a gram-negative, microaerophilic, spiral-shaped bacterium that is oxidase-positive and grows at 42°C. What is the most common Campylobacter species responsible for this presentation?

A 45-year-old man from Delhi with a 2-year history of recurrent epigastric pain and nausea undergoes upper endoscopy, which reveals antral gastritis with intestinal metaplasia. Rapid urease test on antral biopsy is positive. Which is the most common site of Helicobacter pylori colonization in the stomach?

A 32-year-old man from rural India presents with a 3-week history of bloody diarrhea, abdominal cramps, and fever. Stool culture on selective media (Campy food agar) grows oxidase-positive, curved gram-negative rods. Which investigation is most appropriate to confirm the organism as Campylobacter jejuni?