All the following statements about Listeria are true, EXCEPT:

Listeria monocytogenes is a sho coccoid, gram positive, catalase positive non spore forming rod with a tendency to occur in chains. They show tumbling motility at 20 - 25 degree centigrade and is non motile at 37 degree. The major virulence factors are invasion associated surface proteins called internalin and a pore-forming cytotoxin, listeriolysin O (LLO). Ref: Sherris Medical Microbiology By Kenneth J. Ryan, 5th Edition, Chapter 26 ; Textbook of Microbiology By Ananthanarayan and Panicker, 8th Edition, Page 395