Pathogens causing recurrent and difficult-to-treat acute otitis media, 2003-2006.

This study sought to determine the microbiology of recurrent acute otitis media (AOM) and AOM treatment failure (AOMTF) in the context of widespread use of heptavalent pneumococcal conjugate vaccine (PCV7). In this retrospective cohort study, 244 AOM isolates obtained by tympanocentesis during 3 respiratory seasons--2003-2004 (n = 126), 2004-2005 (n = 52), 2005-2006 (n = 66)--from three geographically diverse pediatric populations were compared. Most isolates were from children less than 2 years old, who had received PCV7. For the 3 seasons the proportion of Streptococcus pneumoniae isolates was 35%, 35%, and 46% and for Haemophilus influenzae was 55%, 58%, and 39%, respectively (change in trend, P = .09). A total of 37%, 39%, and 50% of S. pneumoniae were penicillin nonsusceptible (PNSP) and 48%, 67%, and 50% of H. influenzae produced beta-lactamase, respectively. Although H. influenzae remains the most frequently isolated pathogen in children with AOMTF or recurrent AOM, S. pneumoniae that are PNSP are reemerging as important organisms.