**Core Concept**
Bacterial mastitis is an inflammatory condition of the breast tissue caused by bacterial infection, commonly Staphylococcus aureus. This condition often affects lactating women but can also occur in non-lactating individuals.

**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of bacterial mastitis, which involves the invasion of bacteria into the breast tissue. This leads to an inflammatory response characterized by the release of cytokines, chemokines, and other pro-inflammatory mediators. The infection can spread through the ductal system or directly into the parenchyma of the breast, causing pain, swelling, and redness.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because it does not specify the common causative organism of bacterial mastitis. While E. coli can cause urinary tract infections, it is not the primary cause of bacterial mastitis.

**Option B:**
This option is incorrect because it is a general term for breast inflammation and does not specifically indicate a bacterial cause. Other forms of mastitis, such as ductal ectasia or inflammatory breast cancer, do not involve bacterial infection.

**Option C:**
This option is incorrect because it refers to a condition that affects the nipple-areolar complex, often caused by a bacterial or fungal infection. While it can be painful, it is distinct from bacterial mastitis, which affects the underlying breast tissue.

**Clinical Pearl / High-Yield Fact**
Bacterial mastitis is more common in lactating women, especially those with cracked nipples or poor latching technique. It is essential to diagnose and treat bacterial mastitis promptly to prevent complications and promote healing.

**Correct Answer:** D.