Clinical evaluation of early acquisition of Staphylococcus aureus carriage by newborns

Background Little is known about neonatal Staphylococcus aureus carriage. Sites and clinical outcomes of S. aureus colonization during the first month of life were evaluated in this study. Methods A cohort of 279 infants born at term to 277 mothers was included. Maternal S. aureus colonization status was examined before labor. Newborns were screened for nasal, auricular, umbilical, and rectal colonization, one to three times within 100 h after birth, and infants of carrier mothers were re-screened at 1 month. Medical data were recorded from the medical charts at discharge and at the 1-month follow-up interview. Results Overall 43 out of 279 (15.4%) infants acquired S. aureus within the first days of life. The only two predictors of S. aureus carriage in the postnatal period were maternal S. aureus carriage (odds ratio 7.905, 95% confidence interval 3.182–19.638) and maternal antibiotic treatment during labor (odds ratio 0.121, 95% confidence interval 0.016–0.949). Among colonized children, the nose (56%) and rectum (40%) were more frequently colonized, while ear (26%) and umbilicus (16%) colonization were less common. Co-colonization at two sites was rare (4%), but always predicted carriage at 1 month of age. Maternal and neonatal characteristics, including neonatal outcomes, were similar between S. aureus carrier and non-carrier infants during the first month of life. Conclusions Maternal carriage is the major predictor of neonatal S. aureus carriage. The nose and rectum are the main sites of neonatal carriage. S. aureus carriage was not associated with neonatal complications throughout the first month of life. The long-term significance of early S. aureus carriage is yet to be determined.