Which of the following is the cause of donovanosis?
**Core Concept**
Donovanosis, also known as granuloma inguinale, is a sexually transmitted infection characterized by the presence of granulomatous lesions in the genital area. It is caused by a specific bacterium that infects the skin and mucous membranes.
**Why the Correct Answer is Right**
Donovanosis is caused by Klebsiella granulomatis, formerly known as Calymmatobacterium granulomatis. This bacterium infects the skin and mucous membranes, leading to the formation of granulomatous lesions. The bacteria are typically ingested by macrophages, which then attempt to contain and eliminate the infection, resulting in the characteristic granulomatous response.
**Why Each Wrong Option is Incorrect**
**Option A:** Chlamydia trachomatis is the cause of lymphogranuloma venereum (LGV), another sexually transmitted infection, but it is not responsible for donovanosis.
**Option B:** Treponema pallidum is the bacterium that causes syphilis, a different sexually transmitted infection.
**Option C:** Haemophilus ducreyi causes chancroid, yet another sexually transmitted infection.
**Clinical Pearl / High-Yield Fact**
Donovanosis is characterized by painless, progressive ulcers that bleed easily, often accompanied by a foul odor. It is an important consideration in the differential diagnosis of genital ulcers, particularly in regions where the disease is endemic.
**Correct Answer: C. Haemophilus ducreyi is the cause of chancroid, not donovanosis.