AZithromycin Therapy in Preschoolers With a Severe Wheezing Episode Diagnosed at the Emergency Department

This Phase III trial is designed as a parallel group, placebo-controlled, double-blind, randomized, multi-center evaluation of AZ for the treatment of acute wheezing episodes. The study will recruit eligible patients from an estimated six EDs and enroll up to 2,000 patients. We will test two primary hypotheses: 1) AZ (12 mg/Kg/day) given for 5 days to preschool children with severe acute wheezing and harboring any of three specific pathogenic bacteria (H influenzae, M catarrhalis, or S pneumonia) in their nasopharynx will decrease the severity of the acute episode; and 2) AZ given on an identical schedule and dose will decrease the severity of wheezing episodes in children who do not harbor any of these three pathogenic bacteria in their nasopharynx. We will also explore whether variants in the genes encoding for Cadherin Related Family Member 3 (CDHR3), Interleukin-8 (IL-8) and in the 17q asthma-related gene cluster predict response to AZ. This short-term study has three planned visits. All enrolled patients will participate on the Day 0 visit for screening, the informed consent process, enrollment, randomization, treatment initiation and dispensing drug. A sub-group of 370 randomly selected patients will participate in two follow-up visits on Day 5 - 8 and Day 14 - 21 where they will be tested for antibiotic resistance. The primary outcome will be the sum of the Asthma Flare-up Diary for Young Children (ADYC) score, a validated instrument completed by the parent or guardian of the enrolled children during the 5-day treatment period. Secondary outcomes will include (1) ED length of stay (2) hospital length of stay, and (3) return ED visits or hospitalizations within 72 hours after randomization.