**Question:** Most common cause of cellulitis of face is

A. Streptococcal infection
B. Staphylococcal infection
C. Viral infection
D. Unknown

**Core Concept:** Cellulitis is an inflammation of the dermis and subcutaneous tissue, typically caused by bacterial infections. The most common pathogens associated with cellulitis are streptococci and staphylococci.

**Why the Correct Answer is Right:** Staphylococcal infections are the second most common cause of cellulitis, particularly Staphylococcus aureus. Staphylococcal cellulitis usually presents as rapidly spreading, painful edematous skin inflammation, often with purulent discharge. In contrast, streptococcal cellulitis tends to present as a more insidious onset, with less severe pain and purulent discharge.

**Why Each Wrong Option is Incorrect:** Streptococcal infections are the most common cause of cellulitis, particularly Streptococcus pyogenes. Viral infections, such as herpes simplex and varicella-zoster, are typically associated with vesicular lesions and are unlikely to cause cellulitis.

**Clinical Pearl:** A thorough history-taking and physical examination are crucial in differentiating between the various etiologies of cellulitis.

**Why Staphylococcal Infection is the Correct Answer:** Staphylococcal infections, particularly Staphylococcus aureus, are the second most common cause of cellulitis. Staphylococcal cellulitis presents with rapidly spreading, painful edematous skin inflammation and often with purulent discharge.

**Why Viral Infections are Incorrect:** Viral infections, such as herpes simplex and varicella-zoster, are typically associated with vesicular lesions and are less likely to cause cellulitis.

**Why Streptococcal Infections are Incorrect:** Streptococcal infections, particularly Streptococcus pyogenes, are the most common cause of cellulitis. The correct answer is not Streptococcus pyogenes, but Staphylococcus aureus, which is the second most common cause.

**Why Unknown (D) is Incorrect:** The question specifically asks for the most common causes, which are streptococcal and staphylococcal infections. Unknown (D) answers are typically not relevant to the question and should be avoided.

**Correct Answer Explanation:** Staphylococcal cellulitis is characterized by rapidly spreading, painful edematous skin inflammation and often with purulent discharge. A thorough history-taking and physical examination are essential for differentiating between the various etiologies of cellulitis, including viral and unknown causes.