The pathogenic organism responsible for causation of Donovaniasis is-
**Core Concept**
Donovaniasis, also known as granuloma inguinale, is a bacterial infection caused by a gram-negative bacterium. This condition primarily affects the genital area, causing ulcers and lesions.
**Why the Correct Answer is Right**
The pathogenic organism responsible for Donovaniasis is *Klebsiella granulomatis* (formerly known as Calymmatobacterium granulomatis). This bacterium is transmitted through sexual contact, and its infection leads to the formation of granulomatous lesions in the affected area. The bacterium's ability to evade the host's immune response and produce granulomas is a key aspect of its pathogenicity.
**Why Each Wrong Option is Incorrect**
* **Option A:** *Treponema pallidum*, the causative agent of syphilis, is a different bacterium that causes a distinct disease. While both conditions can affect the genital area, they have different clinical presentations and transmission modes.
* **Option B:** *Haemophilus ducreyi* is responsible for chancroid, another sexually transmitted infection, but it is not the causative agent of Donovaniasis.
* **Option C:** *Neisseria gonorrhoeae* causes gonorrhea, a bacterial infection that can affect the genital area, but it is not related to Donovaniasis.
**Clinical Pearl / High-Yield Fact**
Donovaniasis is a notifiable disease in many countries, and its diagnosis relies on the identification of the bacterium in tissue samples or discharge from the affected area. A characteristic histopathological feature of Donovaniasis is the presence of Donovan bodies, which are intracellular inclusions of the bacterium.
**Correct Answer:** C. *Klebsiella granulomatis*