Final answer:
Breast infections are most commonly caused by bacteria, particularly when concerning breastfeeding women. Prompt identification and treatment are essential.
Step-by-step explanation:
Breast infections, commonly known as mastitis, are usually caused by bacteria. The infection typically occurs in breastfeeding women, often due to Staphylococcus aureus entering the breast through a cracked or sore nipple.
This bacteria is part of the normal skin flora but can cause infection if it enters the body. While fungi, viruses, and parasites can also cause infections, bacterial pathogens are the most common cause of breast infections. Identification and treatment of these infections are important to prevent complications.