Inflammation-associated cytokine analysis identifies presence of respiratory bacterial pathogens in the nasopharynx

We sought to determine if inflammatory cytokines are induced during asymptomatic nasopharyngeal (NP) colonization by the common respiratory bacteria Streptococcus pneumoniae (Spn), non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mcat). 85 serum samples were studied from 85 children 6-36 months of age when children were healthy and potentially NP colonized with Spn, NTHi or Mcat. Immunoassays were used to quantitate serum sICAM-1, IL-10 and S100A12 levels. Logistic regression was used to develop a predictive model for NP colonization probability for causative bacterial pathogen presence. Serum levels of sICAM-1, IL-10 and S100A12 increased during asymptomatic NP colonization by Spn, NTHi and Mcat. In a statistical model using risk scoring, we found high positive predictive and negative value, sensitivity and specificity when using these three cytokines to identify the presence of Spn, NTHi and Mcat in the NP. For the first time, we show that inflammatory cytokines are induced in serum during asymptomatic NP colonization by Spn, NTHi and Mcat.