Nasopharyngeal carriage of anaerobes during health and acute otitis media by two years of age.

The nasopharyngeal acquisition of anaerobic bacteria was longitudinally examined among a homogeneous group of Caucasian infants by 2 years of age. Nasopharyngeal swab (NP) samples were collected at scheduled healthy visits at 2, 6, 12, 18, and 24 months of age, and nasopharyngeal aspirates (NPA) during every visit for acute otitis media (AOM). The infants were divided into 4 groups according to the number (0, 1, 2-3, and > 3) of AOM episodes experienced by 2 years of age. At 2 years, the cumulative carriage rates of anaerobic species in these infant groups were 29%, 62%, 89%, and 89%, respectively. Anaerobic species were found in 15/220 (6.8%) of the NP samples and in 34/71 (47.9%) of the NPA samples. Our present results indicate that anaerobic species do not belong to the indigenous nasopharyngeal microflora but only transiently colonize the nasopharynx during AOM.