medwireNews: Research shows that high serum levels of interleukin (IL)-10 indicate that the likely cause of acute otitis media (AOM) is infection with Streptococcus pneumoniae, as opposed to Haemophilus influenzae or Moraxella catarrhalis.

Michael Pichichero (Rochester General Hospital Research Institute, New York, USA) and colleagues hope IL-10 will provide physicians with a biomarker for early diagnosis of S. pneumoniae infection in children with AOM, as infections with this organism compared with other bacteria can result in more severe symptoms and an increased risk for systemic infections.

Based on the premise that infection with S. pneumoniae is associated with greater levels of inflammation than infection with H. influenzae or M. catarrhalis, Pichichero and team collected data from 54 children who were participating in a study supported by the National Institute of Deafness and Communication Disorders to evaluate the potential of IL-10 as a biomarker for S. pneumoniae infection.

The children had serum samples taken at 6, 9, 12, 15, 18, 24, and 30 months of age, which allowed comparison of IL-10 levels when healthy, prior to, and during AOM infection, and during upper respiratory but not AOM infection. Tympanocentesis was used to confirm causative bacteria for AOM.

As reported in The Laryngoscope, the investigators found that AOM caused by S. pneumoniae resulted in serum levels of IL-10 that were 10-fold higher than in the serum of children with AOM caused by other bacteria during but not after the infection. Indeed, levels of IL-10 in the serum of children with H. influenzae or M. catarrhalis infections were not significantly raised over normal levels.

Notably, other inflammatory markers such as IL-4, interferon-γ, and tumor necrosis factor-α did not exhibit similar increases to IL-10 in children with AOM caused by S. pneumoniae.

"Differences in elevation of IL-10 in children at onset of AOM caused by S. pneumoniae infection are consistent with the known role of IL-10 in dampening the innate and adaptive immune response in order to avoid inflammatory damage to tissues," write the authors.

"This result suggests that IL-10 may be a useful biomarker to assist in diagnosis of AOM caused by S. pneumoniae in young children," they conclude.

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