How Do You Get Mastitis?

The breast is made up from 12-20 lobes; each lobe is made up from lobules, which are glandular structures (glands) that produce milk. The lobes and lobules are connected by lactiferous ducts, which carry the milk. Multiple lactiferous ducts connect together and form an ampulla near the nipple and opens up at the nipple. Below the nipple the lactiferous ducts form a reservoir for milk, which is called the lactiferous sinuses. In-between the glandular tissue and ducts, there are fatty tissues. There are no muscles in the breast. During puberty and pregnancy the breast size increase, the size increase during pregnancy is more uniformed.

Lactating/Postpartum Mastitis

Mastitis is caused by a blocked milk duct where the milk and secretions are not cleared. This milk and secretions can back flow to the nearby breast tissue and irritate the tissue causing inflammation. This inflammation is known as mastitis. If microorganism (bacteria) has access to this breast tissue then an infection can develop.

The lining of the lactiferous duct can undergo epidermalization (transformation of glandular or mucosal tissue to stratified squamous tissue) and keratin production. This can cause plugging of ducts. Plugged ducts can block the milk drainage in lactating women. Then, the milk can back flow and cause inflammation of the breast tissue. Postpartum mastitis is seen usually during the 2nd or 3rd week of postpartum (period after pregnancy and delivery).

The organisms can enter the breast through nipple cracks or fissures or sore nipples. Usually Staphylococcus aureus is the organism that commonly cause mastitis, but Staphylococcus epidermidis and Streptococci species also can cause mastitis. Nipple sores, fissures are caused by poor breast attachment and technique during breastfeeding. Infrequent feeding and missed feeds can aggravate the infection. Mastitis can occur in one breast or it can occur in both breasts.

Non-Lactating Mastitis

Mastitis also occur in non-lactating women/peri-menopausal women due to the changes in the breast tissue and reduction of estrogen which leads to duct ectasia. Duct ectasia is widening and shortening of a milk duct in the breast, the thickness of the duct walls increase and ducts secrete a fluid which is thick and sticky. This fluid and blocks the duct. Periductal mastitis (PDM) is also a type of duct ectasia, the milk ducts under the nipple becomes widen and fill with a thick fluid and cause obstruction of the duct. The fluid buildup in duct ectasia and periductal mastitis can irritate the surrounding tissue, which leads to inflammation of the breast tissue.

Smoking is seen in most of the women presenting with duct ectasia and periductal mastitis and it is said that the toxic substances in cigarette smoke directly or indirectly damages the walls of the milk ducts, which leads to inflammation of the ducts. Additionally nipple cracks, fissure or piercing can create a door for the organisms to get inside the breast tissue and cause an infection on top of the inflammation.

Summary

Postpartum/lactating mastitis is caused by a blocked milk duct where the milk and secretions are not cleared. This milk and secretions can back flow to the nearby breast tissue and irritate the tissue causing inflammation. This inflammation is known as mastitis. If microorganism (bacteria) has access to this breast tissue through cracked nipples, fissure or sore nipples, then an infection can develop. Usually Staphylococcus aureus, is the organism that commonly cause mastitis, but Staphylococcus epidermidis and Streptococci species also can cause mastitis. Mastitis also occur in non-lactating women / peri-menopausal women due to the changes in the breast tissue and reduction of estrogen which leads to duct ectasia, and periductal mastitis (PDM). PDM is also a type of duct ectasia. In duct ectasia and PDM, ducts under the nipple becomes widen and fill with a thick fluid and cause obstruction of the duct which leads to inflammation and infection if there are nipple cracks, sores or nipple piercing.

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How Do You Get Mastitis?