- Non-typeable Haemophilus influenzae and Streptococcus pneumoniae (Pnc) are frequently isolated from the nasopharynx (NP) of young healthy children. Colonization of the NP may be detected in early infancy with peaks toward the second year of life. NP carriage of Pnc and especially of antibiotic-resistant Pnc is common and plays an important role in its spread in children, its prevalence increases in those coming into close contact, such as children attending day-care facilities. Several studies show that the presence of older siblings, antibiotic treatment during the month preceding the culture and the attendance at a large day-care center are associated with carriage of drug-resistant Pnc. Significant changes may occur early during antibiotic treatment, and these changes may vary with the use of different antibiotics. Also new strains of Pnc not detected initially emerge, and newly detected organisms are most often resistant to the administered drug. Nasopharyngeal colonization with resistant bacteria was shown to be associated with an increased incidence of acute otitis media with resistant organisms and growing incidence of unresolved otitis media. Preliminary studies show that conjugate pneumococcal vaccine might reduce the nasopharyngeal pneumococcal carriage in general, and of resistant organisms in particular.