Nasopharyngeal bacterial colonization during the first wheezing episode is associated with longer duration of hospitalization and higher risk of relapse in young children.

The purpose of this study was to examine the association between bacterial colonization/infection and respiratory outcomes in children younger than 3 years old who were hospitalized for their first wheezing episode. This was an observational study. The primary outcome was hospitalization time and the secondary outcomes included relapses within 2 months and time to recurrent wheezing (i.e. three physician confirmed wheezing episodes) within 12 months. Bacterial antibody assays for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae and Chlamydia pneumoniae were studied as well as nasopharyngeal bacterial culture for the three former and urine pneumococcal antigen. Nasopharyngeal bacterial culture was positive in 31/52 (60%) children, serologic evidence of bacterial infection was found in 17/96 (18%) children, urine pneumococcal antigen was positive in 24/101 (24%), and any bacterial detection method was positive in 53/106 (50%) children. The children with positive nasopharyngeal bacterial culture had longer duration of hospitalization (hazard ratio 2.4) and more often relapsed within two months than those with negative culture (odds ratio 7.3). In this study, half of the first time wheezing children had bacterial colonization or symptomatic or asymptomatic bacterial infection. The bacterial colonization (i.e. positive nasopharyngeal bacterial culture) was associated with longer duration of hospitalization and higher risk of recurrent wheezing.