Stenotrophomonas maltophilia in patients with bronchiectasis: An analysis of the US bronchiectasis and NTM Research Registry.

Introduction: Little information is available about Stenotrophomonas maltophilia in patients with bronchiectasis. We analyzed data from the US Bronchiectasis and NTM Research Registry to determine its prevalence and association with patient characteristics and severity of disease.

Methods: Baseline and follow-up data were entered into a central web-based database. Patients were grouped into four cohorts based on their baseline cultures: 1) S. maltophilia, no Pseudomonas aeruginsosa, 2) P. aeruginosa, no S. maltophilia, 3) No pathogens, 4) Pathogens other than P. aeruginosa and S. maltophilia. The association between S. maltophilia, demographic characteristics, pulmonary function, exacerbations and hospitalizations was assessed at baseline and one year follow-up.

Results: Among 2659 patients, 134 (5.0%) had grown S. maltophilia at baseline. The prior exacerbation rate at baseline was similar in patients with S. maltophilia and P. aeruginosa, but significantly higher than the other two groups. Hospitalizations were more frequent in patients with S. maltophilia or P. aeruginosa. Pre-bronchodilator FEV1 among S. maltophilia patients was between that of Pseudomonas patients and patients without either organism, but was not significantly different from any of the other groups. For all risk-adjusted one-year outcomes, patients with S. maltophilia had a non-significant trend towards worse outcomes compared to patients without P. aeruginosa, but were more similar to patients with P aeruginosa.

Discussion: Bronchiectasis patients with S. maltophilia may have worse outcomes than patients without this organism or without P. aeruginosa; further study is needed to determine if the non-significant trends we note are clinically significant.