Copyright © 2018 American Academy of Pediatrics. From: Escherichia coli and Other Gram-Negative Bacilli Red Book® 2015, 2015 Figure Legend: Proteus vulgaris on blood agar. Due to its motility, Proteus spp will often appear to be swarming on chocolate and blood agar plates, as in this photograph. It may sometimes have the odor of chocolate cake. Courtesy of Julia Rosebush, DO, Robert Jerris, PhD, Theresa Stanley M(ASCP) Date of download: 1/3/2018 Copyright © 2018 American Academy of Pediatrics. All rights reserved.