Neonates colonized with pathogenic bacteria in the airways have a low‐grade systemic inflammation

Abstract Background and objectives The development of childhood asthma is associated with neonatal colonization with pathogenic bacteria in hypopharynx. Furthermore, established asthma is associated with systemic low‐grade inflammation. We here report on the association between neonatal colonization with pathogenic bacteria in hypopharynx and the development of systemic low‐grade inflammation. Methods Bacterial colonization of the hypopharynx with Moraxella catharralis, Haemophilus influenzae, and/or Streptococcus pneumoniae was assessed in asymptomatic children from the Copenhagen Prospective Studies on Asthma in Childhood 2000 ( COPSAC 2000 ) cohort at age 1 month by culturing technique (N = 238) and by quantitative polymerase chain reaction ( qPCR ) technique (N = 249) and in the COPSAC 2010 cohort by culturing at age 1 month (N = 622) and again at age 3 months (N = 613). Systemic low‐grade inflammation was determined in both cohorts at age 6 months by measuring plasma levels of high‐sensitivity C‐reactive protein (hs‐ CRP ), tumor necrosis factor‐α ( TNF ‐α), and interleukin‐6 ( lL ‐6). Results In both cohorts, bacterial colonization was associated with increased levels of hs‐ CRP : COPSAC 2000 , 1 month culturing (geometric mean ratio of colonized/noncolonized [95% CI ]), 1.39 [0.97‐2.01], P = .08; 1 month qPCR , 1.55 [1.14‐2.10], P < .01; COPSAC 2010 , 1 month, 1.52 [1.23‐1.87], P < .01; and 3 month, 1.57 [1.30‐1.90], P < .01. A multiparametric principal component analysis incorporating hs‐ CRP , TNF ‐α, and IL ‐6 confirmed a systemic inflammatory profile in children colonized with M. catharralis, H. influenzae . and/or S. pneumoniae in the hypopharynx compared to noncolonized children ( P ‐values < .05). Conclusion The composition of the upper airway microbiome in early life may cause systemic low‐grade inflammation.