Ecthyma gangrenosum is caused by?
**Ecthyma Gangrenosum**
**Core Concept**
Ecthyma gangrenosum is a rare, life-threatening skin condition characterized by necrotizing lesions, typically seen in immunocompromised patients. It is caused by a bacterial infection that leads to severe tissue damage and gangrene.
**Why the Correct Answer is Right**
Ecthyma gangrenosum is primarily caused by *Pseudomonas aeruginosa*, a gram-negative bacterium. The bacteria produce exotoxin A, which inhibits protein synthesis and leads to tissue necrosis. The condition is often seen in patients with compromised immune systems, such as those with neutropenia or cancer.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because *Staphylococcus aureus* is a common cause of skin infections, but it is not associated with ecthyma gangrenosum.
**Option B:** This option is incorrect because *Escherichia coli* can cause various infections, but it is not typically linked to ecthyma gangrenosum.
**Option C:** This option is incorrect because *Candida albicans* is a common fungal pathogen, but it is not associated with ecthyma gangrenosum.
**Clinical Pearl / High-Yield Fact**
Ecthyma gangrenosum is a medical emergency that requires prompt recognition and treatment. Early diagnosis and initiation of antibiotic therapy, typically with a broad-spectrum antibiotic such as ceftazidime or meropenem, are crucial in preventing mortality.
**Correct Answer:** D. *Pseudomonas aeruginosa*