The nasopharyngeal culture in acute otitis media. A reappraisal of its usefulness.

Simultaneous cultures of the nasopharynx and middle ear exudate (obtained by tympanocentesis) were obtained from 225 children (mean age, 34 months; median age, 41 months) with suppurative otitis media. A 72% prediction rate for middle ear pathogens was obtained by examining the nasopharyngeal cultures after the strict observance of two essential prerequisites: (1) the nasopharyngeal culture was immediately plated on appropriate solid agar and (2) a semiquantitative method for bacterial enumeration was employed in the reading of the nasopharyngeal culture plates. The technique was most valuable where 2+ (greater than 25% up to 50% of total number of colonies was a single pathogen) or greater of a single pathogen was recovered from the nasopharynx. In only one instance, the semiquantitative nasopharyngeal culture incorrectly predicted the middle ear pathogen if one was recovered. Quantitative nasopharyngeal cultures were particularly useful in predicting the presence of ampicillin-resistant Haemophilus influenzae and group A streptococci as causative agents in otitis media.