Streamlined Treatment of Pulmonary Exacerbations in Pediatrics

The STOP PEDS pilot study demonstrated that a randomized trial of treatment strategies for mild pulmonary exacerbations (PEx) in children with CF was feasible and that assignment to a tailored therapy arm (defined below) may reduce antibiotic exposure. Based on the research priorities identified by CF families and clinicians and the results of the pilot study, the STOP PEDS RCT is a multicenter, parallel, open label randomized controlled trial evaluating the long-term (one year) and short-term safety and efficacy of two antibiotic treatment strategies for the management of outpatient PEx in the pediatric CF population. The two treatment arms are immediate antibiotics and tailored therapy. In both arms, participants will be instructed to increase airway clearance at the onset of an eligible PEx. In the immediate antibiotics arm, they will also begin 14 days of oral antibiotics preselected by their primary CF providers, while in the tailored therapy they will only begin antibiotics if prespecified criteria for worsening symptoms or failure to improve are met. The STOP PEDS study will enroll three cohorts. In the main cohort, children ages 6-18 on highly effective modulator therapy (HEMT) will be enrolled when well and followed for 12 months. Participants will be randomly assigned to a treatment arm and maintain that treatment assignment for all subsequent eligible PEx during their 12-month enrollment period. Two additional pilot cohorts, the preschool cohort (children ages 3 to 5 on HEMT) and the non-HEMT cohort (children ages 6-18 not eligible for HEMT), will be enrolled in parallel pilot studies. Participants will enroll when well and be followed through one randomized PEx. Participants in the STOP PEDS RCT at selected sites will have the opportunity to enroll in optional substudies if eligible. These substudies include: * Clinic throat swab substudy * Home throat and nasal swab substudy * Remote monitoring substudy (Home monitoring of lung function, vital signs, activity and sleep)