"Tropheryma"

"Tropheryma whipplei" is a bacterium that is the causative organism of Whipple's disease, and rarely, endocarditis.

While "T. whipplei" is categorized with the Gram-positive Actinomycetota, the organism is commonly found to be Gram-positive or Gram-indeterminate when stained in the laboratory. Whipple himself probably observed the organisms as rod-shaped structures with silver stain in his original case.