Detection of Pseudomonas aeruginosa in cystic fibrosis after initiation of CFTR modulators: a systematic review

Pseudomonas aeruginosa remains a major cause of morbidity in people with cystic fibrosis (pwCF). The advent of elexacaftor/tezacaftor/ivacaftor (ETI) has transformed clinical outcomes, but its impact on airway microbiology and diagnostic surveillance remains uncertain. We conducted a systematic review of PubMed and Embase (2019–2025) according to PRISMA guidelines, including studies comparing culture with molecular methods for P. aeruginosa detection in pwCF treated with ETI. Fourteen observational studies (n=2525 subjects) were identified. Chronic P. aeruginosa detection declined from 51.4% at baseline to 24.8% after ETI, with nearly half of colonized subjects achieving apparent clearance. Several studies applying molecular techniques reported persistent P. aeruginosa detection despite negative cultures. These findings indicate that ETI markedly reduces bacterial burden and sputum availability, which may limit the sensitivity of culture-based surveillance. However, the clinical and inflammatory significance of PCR+/culture- results remains uncertain. Combining molecular and culture-based surveillance may help guide infection monitoring in the modulator era.