There was little information known on Stenotrophomonas maltophilia in bronchiectasis patients. For a study, researchers examined data from the US Bronchiectasis and NTM Research Registry to see how common it was and how it related to patient characteristics and illness severity. Data from the baseline and follow-up assessments were put into a centralized web-based database. Based on their baseline cultures, patients were divided into four groups: Pseudomonas aeruginosa, no S. maltophilia, P. aeruginosa, no S. maltophilia, No pathogens, and Pathogens other than P. aeruginosa, and S. maltophilia. At baseline and one year later, the connection between S. maltophilia, demographic parameters, pulmonary function, exacerbations, and hospitalizations was examined.

At baseline, 134 (5.0%) of the 2,659 patients had developed S. maltophilia. At baseline, the past exacerbation rate in patients with S. maltophilia and P. aeruginosa was comparable but substantially higher than in the other two groups. Patients with S. maltophilia or P. aeruginosa had a higher rate of hospitalization. Pre-bronchodilator FEV1 in S. maltophilia patients was comparable to that in Pseudomonas patients and those without either bacterium, but not substantially different from the other groups. Patients with S. maltophilia exhibited a non-significant tendency towards poorer outcomes compared to individuals without P. aeruginosa but were more comparable to patients with P aeruginosa for all risk-adjusted one-year outcomes. Individuals with bronchiectasis who have S. maltophilia may have poorer outcomes than patients who do not have the organism or who do not have P. aeruginosa; further research was needed to evaluate whether the non-significant patterns seen were clinically meaningful.