Donovanosis is caused by –
**Core Concept**
Donovanosis, also known as granuloma inguinale, is a sexually transmitted infection characterized by genital ulcers and lesions. It is a bacterial infection caused by a specific species of Gram-negative bacteria.
**Why the Correct Answer is Right**
Donovanosis is caused by *Klebsiella granulomatis* (formerly known as *Calymmatobacterium granulomatis*), a bacterium that enters the body through mucous membranes or breaks in the skin during sexual contact. The bacteria then multiply and cause the characteristic ulcers and lesions. The infection can be diagnosed through direct fluorescent antibody testing or by demonstrating the presence of Donovan bodies, which are clusters of bacteria within histiocytes, in tissue samples.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Donovanosis is not caused by *Treponema pallidum*, the bacterium that causes syphilis. While both infections can cause genital ulcers, they have distinct clinical presentations and diagnostic criteria.
**Option B:** This option is incorrect because *Haemophilus ducreyi* causes chancroid, a different sexually transmitted infection that presents with painful genital ulcers.
**Option C:** This option is incorrect because *Neisseria gonorrhoeae* causes gonorrhea, a bacterial infection that can cause symptoms such as discharge and pain, but not typically ulcers or lesions characteristic of donovanosis.
**Clinical Pearl / High-Yield Fact**
Donovanosis is an important differential diagnosis for genital ulcers, particularly in patients with a history of sexual contact or exposure. It can be challenging to diagnose, so clinicians should consider ordering specific tests, such as direct fluorescent antibody testing or histopathological examination, to confirm the diagnosis.
**Correct Answer: D. Klebsiella granulomatis**