Bacterial flora in the nasopharynx and nasal cavity of healthy young men.

The bacterial flora of the nose and nasopharynx was studied in 86 healthy young men. Common pathogens (Haemophilus influenzae and Streptococcus pneumoniae) were isolated from only 6% of all 172 nasal cavities. The same pathogens were isolated from 27% of 86 nasopharyngeal samples. H. influenzae dominated over S. pneumoniae both in the nose and the nasopharynx. No culture either from the nose or nasopharynx grew Streptococcus pyogenes. Potentially pathogenic bacteria, non-group-A hemolytic streptococci and various groups of Neisseria meningitidis were isolated from the nasopharynx in 20% of the subjects. According to the present study healthy adults do not carry group-A hemolytic streptococci in the nose and seldom if ever in the pharynx. Thus, isolation of S. pyogenes by bacterial culture is suggestive of a bacterial infection by this agent at these sites. Isolation of hemolytic streptococci other than group A from the pharynx does not necessarily indicate bacterial infection, and the same holds true for H. influenzae and S. pneumoniae.