SELECTED ARTICLES FROM THE RECENT LITERATURE 2007

10/15/07

New England Journal Article - Relationship Between Bacterial Colonization of the Hypopharynx in Neonates and the Risk of Developing Asthma in Childhood

Summary
The October 11, 2007, issue of the New England Journal contained an article by Bisgaard, et al., and a related editorial by von Mutius exploring the relationship between bacterial colonization of the hypopharynx in neonates and the risk of developing asthma in childhood. Bisgaard, et al., cultured the hypopharyngeal region of asymptomatic one-month old infants for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Hypopharyngeal samples were cultured from 300 neonates. The results in brief were that colonization with one or more of these organisms (with the exception of S. aureus) was associated with persistent wheeze, acute exacerbation of wheeze, hospitalization for wheeze, and perhaps most importantly for blood eosinophilia and total IgE at 4 years of age. Colonization did not correlate with specific IgE. The authors concluded that such colonization places an infant at increased risk for "recurrent wheeze and asthma early in life."

These results are somewhat unexpected in view of the "hygiene hypothesis" which proposes that bacterial exposure in early life diminishes the risk for atopic disease. Von Mutius postulated that the association between colonization with these bacteria and asthma was perhaps not one of cause and effect, but rather, bacterial colonization was a marker for an immune deficit which itself was related to the development of asthma. She cited studies that identified immune deficits in early life in children at risk for the development of asthma. She postulated that this immune defect might be a component of innate immunity, Toll receptor 2, which is the receptor for the bacteria noted above.

These results are somewhat are perhaps somewhat at odds with the "hygiene hypothesis" which states that increased exposure to bacterial products during infancy and childhood development diminishes the risk of atopic disease.

Thus the verdict at this time is "still out." Obviously, one way to test the significance of Bisgaard's, et al., observation would be to treat at risk infants during early life with antibiotics.

There should be more to come regarding the relationship between early bacterial exposure and the development of atopy.

Reference

  1. Bisgaard, et al. Childhood asthma after bacterial colonization of the airway in neonates. N Engl J of Med 2007; 357:1487-1495.
  2. von Mutius E. Asthma and the microbial world. N Engl J of Med 2007; 357:1545-1546.

 

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