Asthma Healing

A new prospective study has linked bacteria in the digestive tract in infancy to possible asthma later in life.

Investigators showed that early colonization with the bacteria at 3 weeks of age is significantly associated with a positive Asthma Predictive Index (API), a marker used to predict which children will develop persistent asthma.

"Early colonization with Bacteroides fragilis was more often found in recurrent wheezing children at risk of developing persistent asthma at school age," write Carl Vael (University of Antwerp, Belgium) and colleagues in the journal BMC Pulmonary Medicine. "Differences in feeding or use of antibiotics cannot explain the findings."

Intestinal microbial flora have been hypothesized as postnatal regulators of the immune response, particularly the Th1 and Th2 balance, and previous studies have shown differences in the intestinal flora of healthy infants compared with allergic infants.

In this prospective study, the Belgian researchers evaluated the intestinal flora in infants aged 3 weeks, as collected in stool samples by the parents, and followed them up to age 3 years. For follow-up, parents were sent questionnaires every 6 months to collect data on respiratory symptoms and risk factors for asthma.

Of the 117 children participating in the study, 26 (22%) were classified as having a positive API. The presence of colonization with Bacteroides fragilis at 3 weeks was higher in the API-positive children than in the API-negative children (64% vs 34%, p<0.05). In multivariate analysis, colonization with the bacteria was associated with a 4.4-fold increased risk for having a positive API.

"This [API] index was chosen as the outcome parameter for the study since it is at present the best tool for prediction of asthma at school age," comment the researchers.

It is, however, only an approximation to predict which children will develop asthma so further follow-up is needed to determine whether the relationship between early Bacteroides fragilis colonization and API leads to childhood respiratory problems.