A 28-year-old man from rural Maharashtra presents with a 5-day history of crampy abdominal pain and bloody diarrhea. He reports consuming undercooked chicken at a wedding 3 days prior. On examination, he is afebrile with mild abdominal tenderness. Stool microscopy shows motile, curved gram-negative rods. Culture on selective media (Campy food agar at 42°C, microaerophilic conditions) yields oxidase-positive colonies. Which is the most likely organism and its key virulence mechanism?