Several people from a picnic came down with a gastrointestinal disturbance, and public health officials suspected a case of food poisoning. The food was cultured, and after 24 hours of incubation the hot dogs yielded growth on SBA of small, round, smooth, translucent colonies surrounded by a narrow zone of β -hemolysis. A Gram stain showed gram-positive coccobacilli. Motility medium was inoculated and an umbrella pattern of motility was observed at room temperature. What organism was isolated as the cause of the illness?
A) Listeria monocytogenes B) Rhodococcus equi C) Rothia dentocariosa D) Corynebacterium diphtheriae