Bacterial colonization of the nose and external ear canal in newborn infants.

The bacterial flora of the nose and external ear canal of 132 newborn infants, aged 3 days and 4 to 7 days, was examined. Cultures taken from the nose showed the following pattern of bacterial colonization: normal flora (39%); potentially pathologic gram-positive microorganisms (23%); gram-negative enteric rods (16%); and sterile cultures (22%). The most frequent bacterial cultures from nostrils were Staphylococcus epidermidis (39%); Staph. aureus (11%) and Escherichia coli (8%). The cultures from the external ear canal showed normal flora (37%); potentially pathologic gram-positive microorganisms (5%); gram-negative enteric rods (24%); and sterile cultures (34%). The most frequent bacteria cultured from the ear canal were: Staph. epidermidis (37%); E. coli (8%); and Klebsiella pneumoniae (7.5%). Of several factors studied, the type of delivery, Apgar score and the duration of hospitalization were found to have a significant influence on the pattern of bacterial colonization.