The commonest organism causing cellulitis is –
**Core Concept**
Cellulitis is a bacterial skin infection that involves the dermis and subcutaneous tissue. The most common causative organisms are typically gram-positive bacteria that can easily colonize the skin.
**Why the Correct Answer is Right**
The correct answer is due to the virulence and ability of the organism to invade the skin. The organism produces enzymes that break down the skin's natural barrier, allowing it to penetrate deeper tissues and cause infection. The correct answer is also supported by clinical observations and microbiological studies that have consistently shown this organism to be the most common cause of cellulitis.
**Why Each Wrong Option is Incorrect**
**Option A:** This organism is more commonly associated with abscesses and is less likely to cause cellulitis.
**Option B:** This organism is more commonly associated with infections in immunocompromised patients and is less likely to cause cellulitis in healthy individuals.
**Option C:** This organism is more commonly associated with infections in warm, moist environments and is less likely to cause cellulitis in dry skin.
**Clinical Pearl / High-Yield Fact**
The most common cause of cellulitis is often overlooked in the initial stages of the disease, and a high index of suspicion is required for early diagnosis and treatment.
**Correct Answer: D. Staphylococcus aureus**