Evaluation of nasopharyngeal cultures for bacteriologic assessment of acute otitis media in children

Background. The recent emergence of penicillin-resistant Streptococcus pneumoniae, particularly in acute otitis media (AOM), has increased interest in the development of noninvasive procedures that might help to predict the bacterial etiology of this condition. We conducted an open multicenter study to evaluate the predictive value of the nasopharyngeal (NP) sampling in children with AOM by comparing the bacteriologic results of NP cultures with those of pus collected by myringotomy in the same patients. Methods. The NP secretions and the pus obtained by myringotomy were collected concomitantly in 354 children younger than 6 years of age with clinical signs of AOM. The clinical usefulness of NP culture was determined by calculating its sensitivity and specificity, and especially its positive and negative predictive values for the three main pathogens responsible for AOM. Haemophilus influenzae S. pneumoniae and Moraxella catarrhalis. Results. A positive NP culture was found to have little predictive value for H. influenzae (52%), S. pneumoniae (43%) and M. catarrhalis (19%). In contrast the negative predictive value of NP cultures was much greater and was accompanied by negative middle ear fluid cultures in more than 95% of children, especially for S. pneumoniae. Furthermore the incidence of betalactamase-producing strains of H. influenzae at both sampling sites was similar (30 and 35%, respectively), as was the incidence of penicillin-resistant S. pneumoniae (50 and 54%). Conclusion. It appears that the correlation between results of NP and middle ear fluid cultures in children with AOM is too weak to allow NP culture to be recommended for the bacteriologic documentation of this disease. However, these results should not overshadow the considerable epidemiologic value of NP cultures, particularly with reference to the monitoring of pneumococcal susceptibility in children. The collection of NP cultures should therefore be promoted for their collective epidemiologic value.