Transmission of Staphylococcus aureus between healthy, lactating mothers and their infants by breastfeeding.

The authors have investigated Staphylococcus aureus transmission between healthy, lactating mothers without mastitis and their infants by breastfeeding using both bacteriological and molecular-epidemiological methods. They studied 8 healthy, lactating mothers without clinical signs of mastitis and their infants who were less than 3 months old. They collected samples of breast milk, swabs of the mothers' nipples, the infants' nares, and the infants' oral cavities. There was a 50% transmission rate between the pairs. As the result of 12 antibiotics' susceptibility, Methicillin-resistant S. aureus was isolated from 2 of the 4 pairs. Using pulsed-field gel electrophoresis, the authors determined chromosomal DNA restriction patterns of the S. aureus isolated from 4 mother-infant pairs. The DNA fragment patterns of the organism within a given mother-infant pair were indistinguishable or closely related. The results suggest that methicillin-resistant S. aureus or methicillin-sensitive S. aureus may be transmitted between healthy, lactating mothers without mastitis and their infants by breastfeeding.