Longitudinal study of Stenotrophomonas maltophilia antibody levels and outcomes in cystic fibrosis patients

Background: Previous studies have shown an association between higher Stenotrophomonas maltophilia antibody levels and decreased lung function in patients with cystic fibrosis (CF). The purpose of this study was to assess the serologic response to S. maltophilia over time and to determine whether changes in antibody levels could predict clinical outcomes. Methods: Changes in S. maltophilia antibody levels in adult and pediatric patients with CF from 2008 to 2014 were assessed between groups of infection patterns. Regression models accounting for repeated measures were used to assess whether antibody levels could predict subsequent S. maltophilia microbiological status, and whether they are associated with lung function and subsequent pulmonary exacerbation. Results: A total of 409 S. maltophilia antibody samples from 135 CF patients showed that antibody levels did not change significantly between study visits, regardless of infection group. Higher antibody levels were independently associated with future culture positivity (OR 1.62; 95% CI 1.09, 2.41; p = 0.02). While higher antibody levels were not independently associated with decreases in FEV1% predicted, they were associated with an increased hazard ratio for subsequent pulmonary exacerbation (HR 1.3; 95% CI 1.1, 1.6; p < 0.001). Conclusions: S. maltophilia antibody levels may be helpful to identify individuals at risk of exacerbation who may benefit from earlier antimicrobial treatment. (C) 2016 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.