title: Improving the assessment of vancomycin-resistant enterococci by routine screening.
abstract: BACKGROUND
  As infection with vancomycin-resistant enterococci (VRE) increases in hospitals, knowledge about VRE reservoirs and improved accuracy of epidemiologic measures are needed. Many assessments underestimate incidence by including prevalent carriers in at-risk populations. Routine surveillance cultures can substantially improve prevalence and incidence estimates, and assessing the range of improvement across diverse units is important.
  
  
  METHODS
  We performed a retrospective cohort study using accurate at-risk populations to evaluate the range of benefit of admission and weekly surveillance cultures in detecting unrecognized VRE in 14 patient-care units.
  
  
  RESULTS
  We assessed 165 unit-months. The admission prevalence of VRE was 2.2%-27.2%, with admission surveillance providing 2.2-17-fold increased detection. Medical units were significantly more likely to admit VRE carriers than were surgical units. Monthly incidence was 0.8%-9.7%, with weekly surveillance providing 3.3-15.4-fold increased detection. The common practice of reporting incidence using the total number of patients, rather than patients at risk, underestimated incidence by one-third. Overall, routine surveillance prevented the misclassification of 43.0% (unit range, 0%-85.7%) of "incident" carriers on the basis of clinical cultures alone and increased VRE precaution days by 2.4-fold (unit range, 2.0-2.6-fold).
  
  
  CONCLUSIONS
  Routine surveillance markedly increases the detection of VRE, despite variability across patient-care units. Correct denominators prevent the substantial underestimation of incidence.
authors.affiliation: Brigham and Women's Hospital, Channing Laboratory and Department of Infection Control, Harvard Medical School, and Harvard Pilgrim Health Care, Boston, MA 02115, USA. sshuang@partners.org
authors.forename: Susan S
authors.initials: SS
authors.lastname: Huang
authors.forename: Sheryl L
authors.initials: SL
authors.lastname: Rifas-Shiman
authors.forename: Jean M
authors.initials: JM
authors.lastname: Pottinger
authors.forename: Loreen A
authors.initials: LA
authors.lastname: Herwaldt
authors.forename: Teresa R
authors.initials: TR
authors.lastname: Zembower
authors.forename: Gary A
authors.initials: GA
authors.lastname: Noskin
authors.forename: Sara E
authors.initials: SE
authors.lastname: Cosgrove
authors.forename: Trish M
authors.initials: TM
authors.lastname: Perl
authors.forename: Amy B
authors.initials: AB
authors.lastname: Curtis
authors.forename: Jerome L
authors.initials: JL
authors.lastname: Tokars
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Diekema
authors.forename: John A
authors.initials: JA
authors.lastname: Jernigan
authors.forename: Virginia L
authors.initials: VL
authors.lastname: Hinrichsen
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Yokoe
authors.forename: Richard
authors.initials: R
authors.lastname: Platt
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002353:Carrier State / Q000175:diagnosis / Q000517:prevention & control*; D015331:Cohort Studies; D003955:Diagnostic Tests, Routine / Q000592:standards*; D018563:Disease Notification / Q000592:standards; D016983:Enterococcus / Q000187:drug effects* / Q000302:isolation & purification*; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D018802:Patient-Centered Care; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin