Factors affecting the incidence of Stenotrophomonas maltophilia isolation in cystic fibrosis.
OBJECTIVE
To identify factors predisposing cystic fibrosis (CF) patients to Stenotrophomonas maltophilia infection and to determine whether coinfection with S maltophilia affects the clinical response to therapy with tobramycin solution for inhalation (TSI), 300 mg bid.


METHODS
Retrospective review of data collected from two identical, 6-month, randomized, placebo-controlled trials.


METHODS
Sixty-nine CF centers in the United States.


METHODS
Active drug administration of 300 mg TSI.


METHODS
Five hundred twenty CF patients with chronic Pseudomonas aeruginosa endobronchial infections.


RESULTS
A logistic regression analysis identified factors contributing to increased S maltophilia isolation frequency. In this multivariate analysis, the only significant predictors of S maltophilia isolation during the last month of the trial were the concomitant use of oral quinolones (primarily ciprofloxacin; p = 0.0015) and S maltophilia isolation prior to treatment (p < 0.0001). Treatment group, gender, age, use of systemic or inhaled steroids, use of oral sulfonamide, IV cephalosporins, or penicillin antibiotics, baseline FEV(1) percent predicted, and pretreatment Aspergillus isolation were not significant predictors of subsequent S maltophilia infection. In addition, S maltophilia-positive culture frequency was compared to the change in pulmonary function. Patients who either never had culture results positive for S maltophilia or who were positive at <25% of observations had greater clinical response to TSI at the final study visit compared to patients who were positive at > or = 25% of observations.


CONCLUSIONS
TSI therapy did not result in a greater risk for isolation of S maltophilia than standard care alone. In contrast, oral quinolone antibiotic use during the trial was associated with a 2.7-fold increased risk of having a culture positive for S maltophilia (p = 0.0015). The use of TSI to suppress P aeruginosa resulted in improved lung function, regardless of S maltophilia culture frequency. However, improvement was not as great among patients who were persistently coinfected with S maltophilia.
Graff
Gavin R
GR
Department of Child Health, University of Missouri-Columbia, Columbia, MO 65212, USA. graffg@health.missouri.edu
Burns
Jane L
JL
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D003550:Cystic Fibrosis / Q000150:complications*; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D015994:Incidence; D008297:Male; D012189:Retrospective Studies; D020615:Stenotrophomonas maltophilia / Q000302:isolation & purification*; D014031:Tobramycin / Q000008:administration & dosage*
D000900:Anti-Bacterial Agents; D014031:Tobramycin