Streamlined Treatment of Pulmonary Exacerbations in Pediatrics Pilot Study

STOP PEDS is a pilot study of children with CF ages 6-18 across 10 sites in North America. The primary goal is to assess the acceptability and feasibility of a multicenter randomized trial comparing immediate antibiotics versus tailored therapy for pulmonary exacerbation (PEx) treatment in this population. The primary endpoint is the proportion of participants in the tailored arm who did not take any oral antibiotics in the 28 days following randomization. Ultimately, we want to learn: * What is the best way to treat pulmonary exacerbations? * Should everyone with a pulmonary exacerbation take antibiotics? * Do the benefits of starting antibiotics at the first signs of illness outweigh the possible risks, like side effects and antibiotic resistance? This pilot study is designed to determine if an interventional study to help answer these questions is feasible. Up to 120 participants will be enrolled and followed through their well state of health, then for 28 days following their first randomized exacerbation. Enrollment will stop after 80 pulmonary exacerbation events have been randomized, even if this does not require 120 participants. Due to the nature of the study, the identity of treatment assignment will be known to investigators, research staff, and patients (ie, not blinded). Total duration of this pilot study is expected to be approximately 18 months: 6 months for participant recruitment and 12 months for follow up. Participants could be monitored for up to 18 months if they do not have an exacerbation. However, it is anticipated that the majority of participants will experience a randomizable PEx event and therefore have a shorter follow up period.