Clonal similarity of salivary and nasopharyngeal Fusobacterium nucleatum in infants with acute otitis media experience

The environment of an infant's nasopharynx during acute otitis media (AOM) favours the growth of anaerobic bacteria, which can be recovered frequently during infection, but hardly at all if the infant is healthy. The aim of this investigation was to identify the potential source and inoculation route of anaerobes that were present in the nasopharynx. Eleven Fusobacterium nucleatum isolates that were collected through the nasal cavity from the nasopharynx of eight infants with a history of AOM, and 161 F. nucleatum isolates from the saliva of the same infants, were typed to the clonal level by using arbitrarily primed PCR (AP-PCR). In five of the eight infants examined, identical AP-PCR types were found among nasopharyngeal and salivary isolates. As anaerobes seem to be present only transiently in the nasopharynx and salivary contamination of the nasopharyngeal samples can be excluded, this observation indicates that the source of nasopharyngeal anaerobes is the oral cavity and that saliva is their transmission vehicle.