Upregulation of genes for pattern recognition receptors that signal upstream of NF-κB activation (for example, Nod1, Nod2, Tlr2, Tlr4, Tlr6, Tlr7, Tlr9, Nlrp3), cytoplasmic signaling molecules that signal downstream of these receptors (Pycard, Casp1), and mRNAs coding for proteins that interact with NF-κB subunits to regulate activation (Nfkbia, Nfkbib, Nfkbie) indicate complex regulation of and by NF-κB in neutrophils during S. pneumoniae-induced pneumonia. This evidence concerns the gene TLR9 and susceptibility to pneumonia measurement.