The number of varieties of bacteria in the normal flora of the nasal cavity is small, but the character of the flora undergoes interesting alterations, some of which are related to age, as may be gathered from various reports.1 Bloomfieldlb and Kneeland and Daweslc reported that the human upper respiratory tract is sterile at birth but that by 8 months of age the infant has a nasal flora entirely comparable with that of adults. In general, investigators who have worked with adults have observed little change in the nasal flora during the common cold. On the other hand, when children were included in the study significant changes during colds were encountered more frequently.
Kneeland and Daweslc observed 50 infants, both clinically and bacteriologically, over a period of two years and noted a parallel rise in the carrier rate of pathogenic organisms in the nose during two
YANG HS. NASAL FLORA OF THE CHILDREN IN A DAY NURSERY. Am J Dis Child. 1941;61(2):262-272. doi:10.1001/archpedi.1941.02000080052007