Objective: Describe antibiotic utilization pre- and post-widespread utilization of highly effective CFTR modulator therapy at a single pediatric CF center. Design: In October 2019, the United States Food and Drug Administration approved elexacaftor/tezacaftor/ivacaftor (ETI), a highly effective CFTR modulator therapy, for people with CF (pwCF). We performed a single-center, retrospective review of PO and IV antibiotics prescribed for pulmonary exacerbations (PEx) between 1/1/2017 and 12/31/2022. Results: Of the 193 pwCF included, 69 (36%) received a course of IV antibiotics in the pre-ETI period compared to 44 (23%) in the post-period. Oral antibiotic courses decreased from 174 (90%) to 141 (73%) individuals. The median combined IV and PO treatment courses per individual decreased from 3 to 2. The percent of individuals treated for resistant organisms including methicillin-resistant Staphylococcus aureus (46% to 32%) and Pseudomonas aeruginosa (40% to 28%) also decreased from the pre- and post-ETI period. Conclusions: This single center experience indicates a dramatic decrease in PO and IV antibiotics used to treat PEx among pwCF in the post-ETI period.