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Managing Complex Acute Otitis Media Infections
Most acute otitis media (AOM) infections resolve without complications, whether treated with antibiotics or observed under 'watchful waiting.' In recent years, these infections have been termed uncomplicated AOM. However, some children have more serious infections, and these infections have been termed complex AOM.
Michael E. Pichichero, MD
Children with complex AOM have become a focus of investigation by those doing research in the otitis media field, driven by the recognition that these children experience greater consequences from infections, and their medical management accounts for more than half the costs of care associated with AOM.
Complex AOM may be defined according to five differing clinical presentations: 1) recurrent AOM (defined as children with three AOM episodes within 6 months or = 4 AOM episodes within 12 months), ie, otitis prone; 2) treatment failure (second AOM episode occurring within 14 days from an initial AOM visit); 3) relapsed AOM (second AOM episode occurring > 2 weeks from the initial AOM visit but < 1 month from an initial otitis media episode; 4) eardrum rupture; and 5) AOM with local or systemic complications such as mastoiditis, intracranial abscess, or facial nerve palsy.
The frequency of the complex AOM types above are ranked from most to least frequent in the US and other high-income countries. In low- and middle-income countries — where AOM is infrequently diagnosed by clinicians — the frequency of presentation is quite different, with the more common being eardrum rupture and AOM with complications.
My group recently reported results of an 18-year longitudinal study of uncomplicated and complex AOM, spanning 2006-2023, during the 7-valent pneumococcal conjugate vaccine (PCV7) era and throughout the 13-valent PCV (PCV13) era. We enrolled 1537 children prospectively, usually at 6 months old, and followed them to 36 months.
When clinicians made the clinical diagnosis of AOM, tympanocentesis was performed for middle ear fluid culture in most cases. We used the electronic medical records retrospectively to identify uncomplicated AOM and complex AOM episodes. As an inclusion criterion, all children were required to receive the full primary series of PCV7 or PCV13 immunizations according to US Centers for Disease Control and Prevention schedule (doses at 2, 4, and 6, months; booster dose between 12 and 15 months).
Classification of complex AOM was made on an episode basis. If the child met the definition of recurrent AOM, all AOM episodes with middle ear fluid collection were included in the complex AOM group for analysis purposes. One hundred ninety-two children were vaccinated with PCV7 during 2006-2009. Children who received PCV13 immunizations were divided into two groups: 404 children in what we called the early PCV13 era (2010-2014), and 525 children in what we called the late PCV13 era ( 2015-2023).
Among the 1537 enrolled children, the first thing we found is that 591 never had an AOM episode (No OM group, 53%). In the 1980s, 80% of young children were said to have at least one AOM, compared to our new result of 53%. Whether the surprisingly low frequency of AOM was due to PCVs, or changes in the clinical diagnostic criteria for AOM promulgated by the American Academy of Pediatrics in their AOM guidelines, or because parents decreased the frequency of how often they sought care for ear pain in their children, is unknown.
Of the 530 children with at least one episode of AOM, we found that 53% had uncomplicated AOM, 34% had complex AOM, and 13% had both uncomplicated AOM and complex AOM. To our knowledge, this was the first comprehensive report from primary care practices in the US of this distribution of cases of uncomplicated vs complex AOM. Risk factors for complex AOM compared with uncomplicated AOM were male sex, family history of AOM, and daycare attendance.
We found that the frequency of isolating pneumococci from middle ear fluid in episodes of complex AOM decreased over time, between 2006 and 2023. The frequency of isolating Haemophilus influenzae and Moraxella catarrhalis did not change over time. Since pneumococci isolation went down and H influenzae isolation stayed the same, H influenzae became the predominant organism causing complex AOM throughout both PCV13 timespans we studied. Among uncomplicated episodes of AOM, pneumococcal isolation from middle ear fluid remained the same, whereas isolation of H influenzae went up and M catarrhalis went down. Isolation of H influenzae was 44% more likely in children with complex AOM vs uncomplicated AOM. This is consistent with the association between H influenzae and complex AOM, particularly recurrent AOM, as previously reported.
PCV13 significantly reduced the isolation from middle ear fluid strains of pneumococci-expressing various capsular polysaccharide serotypes, throughout the entire timespan that PCV13 was used. The result was consistent with our earlier report in Lancet Child and Adolescent Health , when we studied the effectiveness of PCV13 shortly after its introduction in 2010. However, consistent with a wide literature, over time, pneumococci-expressing PCV13 serotypes were replaced by organisms expressing other serotypes not in the vaccine, especially serotype 35B in the late PCV13 era.
In terms of antibiotic susceptibility, the odds of antibiotic nonsusceptibility of pneumococci to penicillin were 2.65 times higher in children with complex AOM compared to children experiencing uncomplicated AOM. The proportion of H influenzae that was beta lactamase-producing (amoxicillin resistant) increased during the PCV13 eras compared to the PCV7 era.
Key Points:
Risk factors for developing complex AOM and uncomplicated AOM are similar.
PCV13 significantly reduced complex AOM and penicillin nonsusceptibility associated with pneumococci driven by near complete elimination of strains expressing serotype 19A.
H influenzae is the dominant cause of complex AOM.
is the dominant cause of complex AOM. Although non-PCV13 pneumococcal serotypes emerged in the late PCV13 era, the lower level of complex AOM caused by pneumococci remained lower compared to the PCV7 era.
Rochester General Hospital Research Institute was the study sponsor/co-funder and Pfizer provided additional funding for the study analysis that resulted in this paper: N Fuji et al. Eighteen-year longitudinal study of uncomplicated and complex acute otitis media during the pneumococcal conjugate vaccine era, 2006-2023. The Journal of Infectious Diseases , 2025.
Funding was provided by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health and the Centers for Disease Control and Prevention for the collection of middle ear samples leading to the publication.
