Factors Influencing the Establishment of the Neonatal Bacterial Flora

Abstract

Environmental factors, especially seasonal, played an important role in the establishment of the neonatal bacterial flora. Staphylococcus aureus colonization decreased and anhemolytic streptococci increased in the autumn. During the summer, Escherichia coli prevalence reached a peak, as did overall colonization. Additional humidity enhanced nasal colonization of Pseudomonas and E. coli. Topical antibacterial agents reduced umbilical colonization of S aureus and S epidermidis but were associated with a "re-bound" or increase in nasal colonization of E coli and Enterobacter. Among premature infants, systemic antibiotics were associated with reduced nasal colonization of S aureus, anhemolytic streptococci, E coli and "other bacilli" and decreased prevalence of S epidermidis and "other bacilli" on the skin. Environmental factors, especially seasonal, should be considered in evaluating bacteriological studies in newborns.