title: Stenotrophomonas maltophilia ventilator-associated pneumonia. A retrospective matched case-control study.
abstract: BACKGROUND
  Stenotrophomonas maltophilia is increasingly identified in critically ill patients, but it is considered a pathogen with limited pathogenicity and it is therefore infrequently targeted. This study explores whether S. maltophilia may cause ventilator-associated pneumonia (VAP) and whether it affects intensive care unit (ICU) mortality and 28-day mortality when compared to VAP caused by other Gram-negative bacilli.
  
  
  METHODS
  Retrospective analysis of a 19-year prospectively collected database. Stenotrophomonas maltophilia as a cause was considered in VAP-suspected cases when S. maltophilia growth of ≥10(4) cfu/ml was detected in bronchoalveolar lavage fluid analysis. Cases were matched on hospital, gender, age and acute physiology and chronic health evaluation II score in a 1:3 ratio with controls from the same database suffering from VAP caused by other Gram-negative bacilli.
  
  
  RESULTS
  Eight cases met the inclusion criteria, of which three were labelled as 'probable' SM-VAP and three as 'possible' SM-VAP. These six patients constitute 1.8% of all VAPs in the studied period. No significant differences in baseline characteristics and duration of mechanical ventilation (p = 0.68), length of stay in the ICU (p = 0.55) and hospital (p = 0.84) between cases and controls were identified between cases and controls. Intensive care unit mortality odds ratio was 1.7 (p = 0.55; 95% CI 0.3-10.5) and 28-day mortality odds ratio was 1.4 (p = 0.70; 95% CI 0.2-9.1).
  
  
  CONCLUSIONS
  Stenotrophomonas maltophilia is a possible, yet infrequent cause of VAP. No outcome differences were found when compared to matched VAP caused by other Gram-negative bacilli.
authors.affiliation: a Department of Intensive Care Medicine , Luzerner Kantonspital , Luzern , Switzerland ;|b Department of Intensive Care Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Johannes B J
authors.initials: JB
authors.lastname: Scholte
authors.affiliation: b Department of Intensive Care Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Tan Lai
authors.initials: TL
authors.lastname: Zhou
authors.affiliation: b Department of Intensive Care Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Dennis C J J
authors.initials: DC
authors.lastname: Bergmans
authors.affiliation: c Department of Respiratory Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Gernot G U
authors.initials: GG
authors.lastname: Rohde
authors.affiliation: d Department of Methodology and Statistics , Maastricht University, School for Public Health and Primary Care (CAPHRI) , Maastricht , The Netherlands ;
authors.forename: Bjorn
authors.initials: B
authors.lastname: Winkens
authors.affiliation: e Department of Medical Microbiology , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Helke A
authors.initials: HA
authors.lastname: Van Dessel
authors.affiliation: f Department of Intensive Care Medicine and Internal Medicine , Zuyderland Medical Centre , Heerlen , The Netherlands ;
authors.forename: Tom P J
authors.initials: TP
authors.lastname: Dormans
authors.affiliation: g Department of Medical Microbiology , Zuyderland Medical Centre , Heerlen , The Netherlands ;
authors.forename: Catharina F M
authors.initials: CF
authors.lastname: Linssen
authors.affiliation: b Department of Intensive Care Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Paul M H J
authors.initials: PM
authors.lastname: Roekaerts
authors.affiliation: e Department of Medical Microbiology , Maastricht University Medical Centre , Maastricht , The Netherlands ;|h Department of Medical Microbiology & Infection Control , VU University Medical Centre , Amsterdam , The Netherlands.
authors.forename: Paul H M
authors.initials: PH
authors.lastname: Savelkoul
authors.affiliation: b Department of Intensive Care Medicine , Maastricht University Medical Centre , Maastricht , The Netherlands ;
authors.forename: Walther N K A
authors.initials: WN
authors.lastname: van Mook
mesh_terms: D000368:Aged; D058491:Bacterial Load; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D016022:Case-Control Studies; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality / Q000473:pathology; D006801:Humans; D008297:Male; D053717:Pneumonia, Ventilator-Associated / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality / Q000473:pathology; D015995:Prevalence; D012189:Retrospective Studies; D020615:Stenotrophomonas maltophilia / Q000302:isolation & purification*; D016019:Survival Analysis
keywords: Intensive care unit; Stenotrophomonas maltophilia; mechanical ventilation; mortality; multidrug-resistant; ventilator-associated pneumonia