Effectiveness of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening for Reduction of Vancomycin Use for Pneumonia

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization has been a well-established risk for developing MRSA pneumonia. In previous studies, the MRSA nasal screening test has shown an excellent negative predictive value (NPV) for MRSA pneumonia in patients without exclusion criteria such as mechanical ventilation, hemodynamic instability, cavitary lesions, and underlying pulmonary disease. MRSA nasal screening can be used as a stewardship tool to de-escalate broad antibiotic coverage, such as vancomycin. Objective: The purpose of this study was to determine whether implementation of a MRSA nasal screening questionnaire improves de-escalation of vancomycin for patients with pneumonia. Methods: A retrospective review was performed on 250 patients from October 2018 to January 2019 who received MRSA nasal screening due to their prescriber choosing only “respiratory” on the vancomycin dosing consult form. Data obtained included demographics and clinical outcomes. Statistical analyses were performed, and P < .05 was considered significant. Results: Of the 250 patients screened, only 19 patients (8%) were positive for MRSA. Moreover, 40% of patients met exclusion criteria. In 149 patients without exclusion criteria, the MRSA nasal swab had a 98% NPV. Although not statistically significant, vancomycin days of therapy (DOT) based on MRSA nasal swab result was 1 day shorter in those with negative swabs (3.49 days negative vs 4.58 days positive; P = .22). Vancomycin DOT was significantly reduced in pneumonia patients without exclusion criteria (3.17 days “no” vs 4.17 days “yes”; P = .037). Conclusions: The implementation of an electronic MRSA nasal screening questionnaire resulted in reduced vancomycin DOT in pneumonia patients at UAB Hospital. The MRSA nasal swab is an effective screening tool for antibiotic de-escalation based on its 98% NPV for MRSA pneumonia if utilized in the correct patient population.

Funding: None

Disclosures: Rachael Anne Lee reports a speaker honoraria from Prime Education, LLC.