While "T. whipplei" is categorized with the Gram-positiveActinomycetota, the organism is commonly found to be Gram-positive or Gram-indeterminate when stained in the laboratory.[1]Whipple himself probably observed the organisms as rod-shaped structures with silver stain in his original case.[4]
No name was given to the organism until 1991, when the name "Tropheryma whippelii" was proposed after sections of the bacterial genome were sequenced.[5][6] The name was changed to "Tropheryma whipplei" in 2001 (correcting the spelling of Whipple's name) when the organism was deposited in bacterial collections.[1]
As of 2008, the species, genus, and family name are considered to be invalid due to irregularities in the deposition of type material, and are thus styled in quotation marks.[7]
Several strains of "T. whipplei" have been sequenced.[8][9]
Genomes of intracellular or parasitic bacteria undergo massive reduction compared to their free-living relatives. With a genome size of less than 1 Mb, "T. whipplei" is a prime example of genome reduction among Actinomycetota. Other such examples include Mycoplasma for Bacillota (the low G+C content Gram-positive), Rickettsia for Alphaproteobacteria, and Wigglesworthia and Buchnera for Gammaproteobacteria.[8]
^Whipple GH. (1907). "A hitherto undescribed disease characterized anatomically by deposits of fat and fatty acids in the intestinal and mesenteric lymphatic tissues". Johns Hopkins Hospital Bulletin. 18: 382–91.
