Chanchroid is caused by?
**Core Concept**
Chanchroid is a sexually transmitted infection caused by a specific type of bacteria. It primarily affects the genital area, causing painful ulcers and swollen lymph nodes.
**Why the Correct Answer is Right**
Chanchroid is caused by Haemophilus ducreyi, a gram-negative coccobacillus. The bacteria invade the skin and mucous membranes, leading to the formation of painful ulcers and swollen lymph nodes. The infection is typically transmitted through direct contact with an infected person's genital or anal area. Haemophilus ducreyi requires V-factor (NAD+) and X-factor (hemin) for growth, which is why it is often cultured on specialized agar.
**Why Each Wrong Option is Incorrect**
**Option A:** Treponema pallidum, the causative agent of syphilis, is a different type of bacteria that causes a different set of symptoms, including a painless chancre and systemic manifestations.
**Option B:** Neisseria gonorrhoeae, the causative agent of gonorrhea, typically causes a purulent discharge and urethritis, but not the characteristic painful ulcers of chanchroid.
**Option C:** Herpes simplex virus (HSV) can cause painful ulcers, but it is a viral infection, not a bacterial one, and has different transmission and treatment characteristics.
**Clinical Pearl / High-Yield Fact**
Remember that chanchroid is a notifiable disease in many countries, requiring prompt reporting and treatment to prevent further transmission.
**Correct Answer: C. Haemophilus ducreyi.