Staphylococcus Aureus Carrier Status in Breastfeeding Mothers and Infants and the Risk of Lactation Mastitis: A Large Prospective Study

Lactation mastitis is an acute inflammation of the interlobular connective tissue within the mammary gland of a breastfeeding woman. It is a relatively common condition that causes pain and worry, and can lead to restriction in activity and increased risk of early weaning from breastfeeding. Staphylococcus aureus is the infectious agent most commonly implicated in lactation mastitis. It is well established that the anterior nares are the primary reservoir of S. aureus in humans and that approximately 20% of healthy individuals are "persistent carriers" of the organism. Carriage of Staphylococcus aureus has been identified as a significant risk factor for the development of infection including surgical wound infections. It has been suggested that maternal and infant nasal carriage of S. aureus may be associated with an increased risk of breast infection during lactation. We propose to prospectively study the relationship between the S. aureus carrier status of 500 healthy breastfeeding dyads and the rate of the subsequent development of lactational mastitis. Carrier status of mothers and infants will be determined through two nasal swabbings performed in the early post-partum period. The swabs will be analyzed with both traditional culture and through Polymerase chain reaction (PCR) amplification analysis. Mastitis rate will be determined via serial follow-up telephone interviews during the first two months post-partum.