Lung function in children with recurrent bronchitis

Genotype analysis and phenotypic manifestations of children with intermediate sweat chloride test results

STUDY OBJECTIVES

Cystic fibrosis (CF) is one of the most common inherited diseases among whites. Since the cloning of the CF transmembrane conductance regulator (CFTR) gene, a number of studies have focused on associations between the genotype and phenotype in CF. This had led to the progressive identification of new groups of patients, including those who have mild lung disease and those who have normal sweat chloride values (< 60 mEq/L). The aim of the present work was to provide information on the genotype and the phenotypic characteristics of children with intermediate-range sweat chloride test results.

PATIENTS AND RESULTS

We focused on children referred to the pulmonary department for various types of pulmonary disease and who had several sweat chloride test results with median values in the range of 40 to 60 mEq/L. Twenty-four patients over a 10-year period were enrolled (mean age, 4.8 years). Respiratory manifestations at initial evaluation included recurrent bronchitis, wheezing, chronic cough, and pneumonia. The duration of the follow-up ranged from 0.5 to 10.5 years. Sputum cultures revealed the presence of Haemophilus influenzae (10 children), Staphylococcus aureus (4 children), and Pseudomonas aeruginosa (3 children). Pancreatic insufficiency was found in two patients. Analysis of the entire coding sequence allowed identification of 16 known mutations in CFTR gene. Fifteen chromosomes (31.2%) carried a mutation in CFTR gene and one allele carried two mutations. Three patients were homozygous or double heterozygous (DeltaF508/DeltaF508, DeltaF508/3849 + 10 kb C-->T, S1235R/G551D). The 5-thymidine allele was identified in four children.

CONCLUSION

These results indicate an higher frequency of CFTR gene mutations in patients with borderline sweat chloride test results, compared to data reported in the general population. They lead to the recommendations for complete pulmonary and GI investigations in this group of patients, as well as assiduous care and medical follow-up.

Daycare attendance and risk of first infectious disease

The health hazards of daycare attendance for the development of upper and lower respiratory tract infections have been well documented; however the importance and the mechanism of this association have not been well defined. In order to ascertain the risk associated with the beginning of daycare (DC) attendance we conducted a survey on 1263 children aged from 3 months to 3 years; the analysis focused on the risk of developing an initial episode of common cold with fever, a first otitis and a first wheezy bronchitis (WB) within the 2 month period following admission to DC. For each 2 month period, the risk of a first infectious event was much higher in children who had just begun attending DC than in children who remained at home; the risk ratio varied from 1.7 to 2.4 for common cold, from 1.5 to 1.9 for otitis and from 1.8 to 3.2 for WB. Because age at onset of the first infectious event may be related to a higher risk of repeated events we consider that admission to DC under 12 months of age should be questioned.

The chronic bronchitis complex in children

In childhood, a clear definition, etiology, natural history, therapy, and prognosis have not been described for chronic bronchitis. In fact, its validity as a single disease entity is in question. This article offers a pragmatic approach by considering "chronic bronchitis" as a pathophysiologic description of a symptom complex that results from the interaction of both intrinsic and extrinsic factors. In this schema, the physician should rule out more specific diagnoses and prevent further airway disease by limiting exogenous causes of airway damage and treating identifiable endogenous ones.