title: The influence of metallo-beta-lactamase production on mortality in nosocomial Pseudomonas aeruginosa infections.
abstract: OBJECTIVE
  To assess the effect of metallo-beta-lactamase (MBL) production on Pseudomonas aeruginosa nosocomial infection mortality and to identify the determinants of such effect.
  
  
  METHODS
  A cohort study of patients with P. aeruginosa nosocomial infections was conducted at two teaching hospitals. MBL was detected by ceftazidime/2-mercaptopropionic disc approximation test and selected isolates were submitted to PCR using bla(SPM-1) primer. Molecular typing was performed by DNA macrorestriction. To evaluate the influence of MBL on mortality a Cox proportional hazards model was performed using a hierarchized framework of the variables.
  
  
  RESULTS
  A total of 298 patients with P. aeruginosa infections were included. Infections by MBL-carrying Pseudomonas aeruginosa (MBL-PA) resulted in higher in-hospital mortality than those by non-MBL-PA (51.2% versus 32.1%, respectively; relative risk 1.60, 95% CI 1.20-2.12) and higher mortality rates [17.3 per 1000 versus 11.8 per 1000 patient-days, respectively; hazard ratio (HR) 1.55, 95% CI 1.06-2.27]. In the final multivariate model, severe sepsis or septic shock [adjusted HR (AHR) 3.62, 95% CI 2.41-5.43], age (AHR 1.02, 95% CI 1.01-1.03) and use of appropriate therapy<or=72 h (AHR 0.49, 95% CI 0.32-0.76) were significantly associated with mortality. Fourteen MBL-PA tested carried the blaSPM-1 gene. Clonal dissemination was documented in both hospitals.
  
  
  CONCLUSIONS
  MBL-PA infections resulted in higher mortality rates most likely related to the severity of these infections and less frequent early institution of appropriate antimicrobial therapy. Empirical treatments should be reviewed at institutions with high prevalence of MBL.
authors.affiliation: Infectious Diseases Service, Hospital São Lucas da Pontifícia Universidade Católica do Rio Grande do Sul Porto Alegre, Brazil. apzavascki@terra.com.br
authors.forename: Alexandre Prehn
authors.initials: AP
authors.lastname: Zavascki
authors.forename: Afonso Luís
authors.initials: AL
authors.lastname: Barth
authors.forename: Ana Lúcia Saraiva
authors.initials: AL
authors.lastname: Gonçalves
authors.forename: Ana Lúcia Didonet
authors.initials: AL
authors.lastname: Moro
authors.forename: Juliana Fernandez
authors.initials: JF
authors.lastname: Fernandes
authors.forename: Andreza Francisco
authors.initials: AF
authors.lastname: Martins
authors.forename: Fabiano
authors.initials: F
authors.lastname: Ramos
authors.forename: Luciano Zubaran
authors.initials: LZ
authors.lastname: Goldani
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D003428:Cross Infection / Q000382:microbiology* / Q000401:mortality*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D007297:Inpatients; D008297:Male; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011552:Pseudomonas Infections / Q000382:microbiology* / Q000401:mortality*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D012307:Risk Factors; D018805:Sepsis / Q000401:mortality; D012772:Shock, Septic / Q000401:mortality; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D004269:DNA, Bacterial; D001618:beta-Lactamases