Chronic Stenotrophomonas maltophilia infection and exacerbation outcomes in cystic fibrosis.

Background: Chronic Stenotrophomonas maltophilia infection is a risk factor for pulmonary exacerbation in cystic fibrosis (CF) but its impact on subsequent clinical outcomes is unknown. The aim of this study was to determine the effect of chronic S. maltophilia infection and associated antimicrobial therapy on the recovery of forced expiratory lung volume in 1s (FEV(1)) following pulmonary exacerbation.

Methods: This was a retrospective cohort study of patients with CF followed at The Hospital for Sick Children and St. Michael's Hospital from 1997 to 2008. The primary outcome was the difference in FEV(1) percent predicted from baseline to follow up after a pulmonary exacerbation. Secondary outcomes for the effect of antimicrobial therapy included time to subsequent exacerbation.

Results: There were 1667 pulmonary exacerbations in 440 CF patients. Patients with chronic S. maltophilia infection did not recover their baseline FEV(1) following 31% of exacerbations and had an overall mean FEV(1) decline of 1.84% predicted after exacerbation. Older (p=0.02), female (p=0.02) patients with lower BMI z score (p=0.002) and Burkholderia cepacia complex infection (p=0.005), but not chronic S. maltophilia infection (p=0.86), had a greater decrease in follow up FEV(1)% pred compared to baseline. The number of days of antibiotic therapy against S. maltophilia during a pulmonary exacerbation was not associated with a significant difference in the FEV(1) recovery (p=0.69) or with a longer time to subsequent pulmonary exacerbation (p=0.56).

Conclusions: Although CF patients experience a significant decline in lung function following exacerbation, chronic S. maltophilia infection and associated antimicrobial therapy do not affect subsequent lung function recovery.