Improving the Assessment of Vancomycin-Resistant Enterococci by Routine Screening

• Published in: The Journal of infectious diseases Vol. 195; no. 3; pp. 339 - 346
• Main Authors: Huang, Susan S., Rifas-Shiman, Sheryl L., Pottinger, Jean M., Herwaldt, Loreen A., Zembower, Teresa R., Noskin, Gary A., Cosgrove, Sara E., Perl, Trish M., Curtis, Amy B., Tokars, Jerome L., Diekema, Daniel J., Jernigan, John A., Hinrichsen, Virginia L., Yokoe, Deborah S., Platt, Richard
• Format: Journal Article
• Language: English
• Published: United States The University of Chicago Press 01-02-2007; University of Chicago Press
• Subjects: Academic Medical Centers; Adult; Anti-Bacterial Agents - pharmacology; Bacteria; Carrier State - diagnosis; Carrier State - prevention & control; Cohort Studies; Density; Diagnostic Tests, Routine - standards; Disease Notification - standards; Enterococcus; Enterococcus - drug effects; Enterococcus - isolation & purification; Epidemiology; Gram-Positive Bacterial Infections - diagnosis; Gram-Positive Bacterial Infections - prevention & control; Hospital admissions; Humans; Incidence; Infection control; Infections; Intensive care units; Patient surveillance; Patient-Centered Care; Preventive medicine; Retrospective Studies; Staphylococcus aureus; Surveillance; United States - epidemiology; Vancomycin - pharmacology; Vancomycin Resistance; United States
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1086/510624

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.