TLR9 and infectious otitis media: We chose to study expression of Toll-like receptor (TLR) response cytokine genes that are likely to be activated by NTHi ligands binding to TLRs (e.g. TLR2, TLR4, TLR9) that are expressed by macrophages, monocytes and neutrophils (http://www.immgen.org) and are relevant to OM and AOM (Juhn et al., 2008; Kaur et al., 2015).