What is the most common cause of mastitis in breastfeeding women?

The most common cause of mastitis in breastfeeding women is Staphylococcus aureus. This bacterium is known to colonize the skin and can enter the breast tissue through irregularities in the nipple, such as cracks or fissures, which are not uncommon in lactating women. Once S. aureus enters the breast tissue, it can lead to inflammation and infection, resulting in the symptoms associated with mastitis, such as localized breast pain, swelling, and sometimes systemic symptoms like fever.

The other bacteria listed, while they can cause infections in different contexts, are not typically associated with mastitis in breastfeeding women. Escherichia coli is more commonly associated with urinary tract infections and gastrointestinal issues. Streptococcus pneumoniae primarily causes respiratory infections and meningitis, and Listeria monocytogenes is linked to foodborne illnesses, particularly in pregnant women, but is not a common cause of mastitis. Therefore, Staphylococcus aureus stands out as the prevalent infectious agent in cases of mastitis among breastfeeding women.