title: Determination of risk factors associated with isolation of linezolid-resistant strains of vancomycin-resistant Enterococcus.
abstract: OBJECTIVE
  To identify independent risk factors associated with isolation of linezolid-resistant, vancomycin-resistant Enterococcus (VRE).
  
  
  METHODS
  A retrospective, case-case-control study.
  
  
  METHODS
  A tertiary care, academic medical center.Methods. VRE isolates from clinical cultures were retrospectively analyzed for linezolid resistance during our 18-month study period. Clinical data were obtained from electronic patient records, and the risk factors associated with isolation of linezolid-resistant VRE were determined by comparison of 2 case groups with a control group.
  
  
  RESULTS
  A total of 20% of the VRE isolates analyzed during the study period were linezolid resistant, and resistant isolates were most commonly recovered from the urine (40% of resistant isolates). Risk factors found to be associated with isolation of linezolid-resistant VRE were peripheral vascular disease and/or the receipt of a solid organ transplant, total parenteral nutrition, piperacillin-tazobactam, and/or cefepime. Only 25% of patients from whom linezolid-resistant VRE was isolated had previous linezolid exposure, and in the multivariate model this was not found to be a risk factor associated with the isolation of linezolid-resistant VRE.
  
  
  CONCLUSIONS
  The results of this analysis suggest that there is horizontal transmission of linezolid-resistant VRE in our institution and highlight the need for improved infection control measures. Furthermore, the high incidence of linezolid-resistant VRE demands a reassessment of our empirical antibiotic selection for patients infected with VRE.
authors.affiliation: Department of Pharmacy and Therapeutics, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Pogue
authors.forename: David L
authors.initials: DL
authors.lastname: Paterson
authors.forename: A William
authors.initials: AW
authors.lastname: Pasculle
authors.forename: Brian A
authors.initials: BA
authors.lastname: Potoski
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016022:Case-Control Studies; D003428:Cross Infection / Q000188:drug therapy / Q000209:etiology*; D018562:Disease Transmission, Infectious; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D016983:Enterococcus / Q000187:drug effects* / Q000302:isolation & purification; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000635:transmission; D006785:Hospitals, University; D006801:Humans; D000069349:Linezolid; D008297:Male; D008875:Middle Aged; D023303:Oxazolidinones / Q000494:pharmacology*; D010289:Parenteral Nutrition, Total / Q000009:adverse effects; D016491:Peripheral Vascular Diseases / Q000150:complications; D012189:Retrospective Studies; D012307:Risk Factors; D019737:Transplants / Q000009:adverse effects; D020713:Vancomycin Resistance / Q000187:drug effects*
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D000069349:Linezolid