A cluster of methicillin-sensitive Staphylococcus aureus colonization in a nursery

Background: Staphylococcus aureus is among the most important pathogens of bacteremia in hospitals. Colonizing strains may spread to other patients. Methods: Ninety-two mothers visiting delivery rooms were included in this study. From the mothers, specimens were obtained from the nares and vagina for the detection of S. aureus. From the babies, specimens were obtained from the nares and umbilicus within 24 h in the nursery. Results: The carriage rates of S. aureus were 25% in the parturient mothers and 30.9% in their babies. The majority (55 isolates, 94.8%) of the isolates were methicillin-sensitive S. aureus (MSSA). Of the 55 MSSA isolates, 11 genotypes were identified for isolates from the mothers and five genotypes for isolates from the infants. A major clone was identified and accounted for 82% of 34 isolates from the babies. Nine pairs of mothers and babies were colonized with MSSA; by molecular methods, the paired isolates were indistinguishable in two pairs. Conclusion: Newborn babies acquire S. aureus colonization soon after birth, partly from their mothers. Once S. aureus is introduced into a nursery, spread of the strain may occur if health-care workers do not execute infection control measures strictly.