Impact of Achromobacter xylosoxidans isolation on the respiratory function of adult patients with cystic fibrosis

Abstract

BackgroundThe prevalence of Achromobacter xylosoxidans lung isolation in cystic fibrosis (CF) patients has increased, but the impact on lung function is controversial. The aim of this study was to evaluate the long-term effects of A. xylosoxidans isolation on respiratory function of adult patients with CF in the first 3 years after identification of A. xylosoxidans isolation.MethodsThis was a case–control retrospective study performed at a single CF centre in Lille, France. Data for 36 patients with CF who had at least one sputum culture positive for A. xylosoxidans (Ax+) were evaluated and compared with control CF patients uninfected by A. xylosoxidans (Ax−). Respiratory function and exacerbation frequency were evaluated between 1 year prior to and 3 years after A. xylosoxidans isolation.ResultsCompared with the Ax− group, the Ax+ group had a lower forced expiratory volume in 1 s (FEV1) at baseline (median (interquartile range): 55.2% (50.6–59.8%) versus 73.8% (67.2–80.4%); p=0.005), a greater decline in FEV1 (±se) in the first year after A. xylosoxidans identification (−153.6±16.1 mL·year−1versus −63.8±18.5 mL·year−1; p=0.0003), and more exacerbations in the first 3 years after A. xylosoxidans identification (9 (7–12) versus 7 (5–10); p=0.03). Ax+ patients co-colonised with Pseudomonas aeruginosa (n=27, 75%) had a greater FEV1 decline (p=0.003) and more exacerbations in the year after A. xylosoxidans identification (p=0.037) compared with patients colonised with A. xylosoxidans alone. Patients with chronic A. xylosoxidans isolation (n=23, 64%) had more exacerbations than intermittently colonised patients in the 3 years after A. xylosoxidans identification (p=0.012).ConclusionA. xylosoxidans isolation is associated with a decline in respiratory function in patients with CF. Chronic A. xylosoxidans isolation and P. aeruginosa co-isolation may be markers of more severe respiratory disease in Ax+ patients.