Donovan bodies are associated with donovanosis; the causative organism cannot be cultured on routine media. Which organism is this?

• A. Treponema pallidum
• B. Calymmatobacterium granulomatis
• C. Mycobacterium leprae
• D. Francisella tularensis

Answer: (B)

Donovanosis is caused by Calymmatobacterium granulomatis, now reclassified as Klebsiella granulomatis. In tissue from lesions, macrophages contain Donovan bodies—intracytoplasmic, safety-pin–shaped inclusions that stain with Giemsa or Wright and are diagnostic for this infection. This organism is notoriously not cultivable on routine artificial media, which fits the clue about growth in standard labs. The other organisms listed cause different diseases and do not produce Donovan bodies in lesions: for example, Treponema pallidum causes syphilis and isn’t associated with these inclusions; Mycobacterium leprae causes leprosy and is also difficult to culture but lacks Donovan bodies; Francisella tularensis causes tularemia and has its own distinct culture characteristics.