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es s f c e ta markedly. In a recent patient safety project at 3 ma- sporadically occurring clones, and to disprove person-ternity units in the County of Jönköping, Sweden, we observed a 30 % S aureus colonization of infants who were delivered by mothers without S aureus carriage. This indicated a nosocomial cross colonization, despite the fact that the infants are roomed in with their mothers, and that health care workers are supposed to follow accurate hand disinfection routines in their care. Ideally, infants should receive their normal flora from their parents. Many hospital-acquired infections result from patient colonization with hospital flora, to-person transmission in hospitals.8-10 In this study, S aureus colonization of infants, their parents, and staff members at 3 maternity units was measured. Samples also were obtained from the envi-ronment. By using spa typing of S aureus isolates, we could show that transmission from staff members to infants is still of major concern. METHODS Study population and samples S aureus colonization of infants, their parents, and staff members was measured at 3 maternity units in the County of Jönköping (Sweden). Infants were routinely roomed in with their mothers, in rooms with 2 to 4 beds, and they shared diaper-changing tables. Participants gave their informed consent. New-born infants and their parents were sampled on 6 occasions during one year (2003-2004). Members of the staff (99 % women) were sampled at the first and sixth occasion. Samples were obtained from parents (n = 463) when entering the ward, with swabs from the nostrils, ears, and fingers. From infants (n = 218