Prediction of pre-operative nasal carriage of meticillin-resistant Staphylococcus aureus in an outpatient evaluation clinic by using a simple questionnaire

Abstract number: P1763

Schuermans A.M.R.F.R., Nuyttens R., Vandermeulen E., Degeest I., Cossey V.

Objectives: To develop a questionnaire based on known risk factors for nasal carriage of Meticillin resistant Staphylococcus aureus (MRSA) and to test this instrument for sensitivity, specificity positive predictive value (PPV) and negative predictive value (NPV) in a preoperative outpatient evaluation clinic at the University Hospitals Leuven. This questionnaire would allow a more selective screening for MRSA carriage, the recovery rate of the systematic nasal screening for MRSA being only 1.36% at that moment.

Methods: As a standard of care, all patients presenting at the preoperative outpatient clinic are screened for nasal carriage of MRSA. A questionnaire including 7 questions (prior hospitalisation in the last year, resident of a long term care facility, antibiotic use in the last 6 months, presence of a chronic wound, presence of diabetes, healthcare worker or professional contact with animals and prior carriage of MRSA?) was developed.

During February 2007, all patients were asked to answer the questionnaire. Sensitivity, specificity, PPV, NPV, and likelihood ratio of a positive and negative test result (LR+ and LR-) were calculated, both when patients answered positive on 1 of the 7 questions (cut-off value of 1) and on 2 of the 7 questions (cut-off value of 2). No difference was made between the questions.

Results: 680 patients answered the questionnaire.

At a cut-off value of 1, a sensitivity of 100% and a specificity of 40% was measured (PPV 2.2% and NPV 100%, LR+1.6 and LR-0).

By using a cut-off value of 2 instead of 1, the sensitivity dropped to 67% and the specificity rose to 74% (PPV 3.3% and NPV 99%, LR+2.5 and LR-0.4).

Conclusion: By using a simple questionnaire with a limited number of questions and a cut-off value of 1, all MRSA positive patients were identified and a reduction of 40% of the microbiological analysises was possible. This reduction in the number of screening samples has a considerable financial impact and no consequences on the recovery rate of MRSA positive patients in our preoperative outpatient evaluation clinic.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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