Demonstration of mother-to-infant transmission of Staphylococcus aureus by pulsed-field gel electrophoresis

We assessed mother-to-infant transmission of Staphylococcus aureus. Anterior nares swabs of 466 pregnant women, vaginal swabs of 305 of these women and anterior nares swabs of 305 6-day-old infants were examined for the presence of S. aureus. The results showed that 7.5% of the vaginal swabs from the pregnant women and 10.1% of the anterior nares swabs from the infants were positive for S. nca-eus. Six of the 466 pregnant women (1.3%) and 12 of the 305 infants (3.9%) carried methicillin-resistant S. aureus (MRSA) in the anterior nares site, but none of the vaginal specimens were positive for MRSA. Analysis of SmaI digested chromosomal DNA analysis using pulsed-field gel electrophoresis (PFGE) showed that methicillin-sensitive S. aureus (MSSA) strains obtained from four pairs of pregnant women and their infants were completely identical, which strongly suggesting mother-to-infant transmission of S. aureus. Conclusion This study elucidated the. prevalence of S. aureus carriage among pregnant women and new-born infants. Mother-to-infant infection of S. aureus was demonstrated phenotypically and genetically. PFGE is a useful tool to det tectinfecfion routes including mother-to-infant-infection.