Bacterial colonization of newborn infants in a neonatal intensive care unit.

The bacterial colonization of the nose, umbilicus, perineum and faeces in 85 newborns was studied during one period of high and one of low occupancy in a neonatal intensive care unit. Cultures were taken on admission, at three days, at one week of age, and then weekly during the stay in the unit. Colonization took place early and potential pathogens were responsible for a significant part of the spectrum. At one week of age, more than 50% of the infants had Staphylococcus aureus in the nose and umbilicus, 25% had E. coli and/or Klebsiella enterobacter in the umbilicus, and 60% had Klebsiella enterobacter in the perineum. Neither the occupancy rate in the unit nor the clinical state of the infant seemed to influence the colonization pattern significantly. Changes in flora were frequent in the individual infant. However, the bacterial spectrum remained essentially the same with increasing age during the stay in the unit and during the two periods. Only on two occasions was the same phage type of Staphylococcus aureus found in two infants at the same time. Two cases of septicemia occurred in the 85 infants during the three months of the study. Both infants were colonized beforehand with the causative organism. The results may indicate that the clinical state of the infant is of greater importance for risk of septicemia than the pattern of the bacterial colonization.