Improving efficiency in active surveillance for Methicillin-Resistant Staphylococcus aureus or Vancomycin-resistant Enterococcus at hospital admission

Background: Currently, VA mandates active surveillance culturing of all patients admitted to VA acute care hospitals. This effort is likely cost-inefficient and could be improved. Clinical prediction rules have been used to efficiently identify patients at high risk of colonization with Methicillin-Resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE).

Objective: Examine if high-risk patients can be identified using a simple prediction rule and targeted for MRSA (and also VRE) screening, and if this might be cost-effective. We aimed to determine the clinical efficacy of such prediction rules in a Veterans Hospital.

Methods: We conducted a prospective cohort study of all adult inpatients admitted to the medical and surgical wards (non-ICU) of a tertiary-care Veterans Affairs hospital. In the first 48 hours of admission, patients were approached for consent, administered a 44-item questionnaire and received nasal culture for MRSA, and a subset received perirectal culture for VRE.

Results: Out of the initial 608 patients enrolled, 594 underwent nasal cultures and 241 underwent perirectal cultures. Overall, 10.6% were MRSA positive and 7% were VRE positive. Patient self-report of having received antibiotics in the past year was the most sensitive single predictor for MRSA (76%); specificity was 45% (relative risk (RR)= 2.4 (95%CI 1.4 - 4.2), p=0.01). This rule had a sensitivity of 81% for VRE (RR=3.7 (95% CI 1.1 – 12.6), p=0.04). Use of this predictor would require swabbing only 57% of admissions. A prediction rule using self-report of hospitalization in the past year would have identified 67% and 88% of patients colonized with MRSA or VRE, respectively and require swabbing only 55% of admissions. A prediction rule combining self-report of hospitalization and having received antibiotics would have identified 86% and 94% of patients colonized with MRSA and VRE, respectively; requiring swabs in 73% of admissions.

Conclusions: Patient self-report of receiving antibiotics within the past year identifies a group of patients at high-risk for colonization with MRSA or VRE in our VA acute care population that could be considered for targeted active surveillance culturing. This approach has the potential for significant cost-savings compared to the current practice of universal active surveillance and should be validated at other VA hospitals.