1489 - Safety and Performance of a Pharmacist-Driven Nasal MRSA PCR Protocol for De-escalation of Empiric Vancomycin for Suspected Pneumonia at an Academic Medical Center

Background: Limited published data supports the de-escalation of empiric anti-methicillin resistant Staphylococcus aureus (MRSA) antibiotics for suspected pneumonia upon negative nasal MRSA screening.  Besides limited sample sizes, special populations, such as those who are immunocompromised and/or critically ill, have been underrepresented in these reports.  We describe real-world efficacy and safety of a pharmacist-driven nasal MRSA PCR testing protocol implemented at Stanford Health Care in May 2018 across a diverse patient population.

Methods: This was an observational cohort study of adult patients who received vancomycin for empiric pneumonia before (PRE) vs after (POST) implementation of a pharmacist-driven nasal MRSA PCR testing protocol (between 05/01/2017 - 08/31/2017 (PRE) and 5/7/2018 - 12/31/2019 (POST). The primary outcome measure was duration of vancomycin administration. Secondary outcomes included time to vancomycin discontinuation, frequency of restarting vancomycin for empiric pneumonia within 7 days, acute kidney injury (defined as “risk” by RIFLE criteria), and MRSA respiratory cultures. Statistical methods are described in Figure A.Figure A. Statistical methods


Results: Total of 610 patients were included in this study with 116 in the PRE group and 494 in the POST group. Over 40% were critically ill and approximately 37% were immunocompromised in both groups (Table 1).  For the primary outcome, median vancomycin duration was significantly shorter in the POST group (1.29 days; 95% CI 1.13-1.45) vs. PRE group (1.98 days; 95% CI 1.49-2.46) (p < 0.0005), a 34.8% reduction (Figure 1). Median vancomycin duration was lower in patients with a negative vs positive nasal MRSA PCR (1.20 days [95% CI 1.08-1.33] vs 2.53 days [95% CI 1.77-3.29], p < 0.0005), a 52.6% reduction (Figure 2). MRSA was recovered in respiratory cultures in 1.7% vs 1.4% in the PRE vs POST groups. One (0.002%) patient had a negative nasal MRSA PCR but culture-confirmed MRSA pneumonia and recovered after completing a treatment course. Secondary safety outcomes were similar between groups (Table 2).Tables 1 and 2: Baseline Characteristics and Secondary Outcomes
Figure 1. Primary Outcome: Kaplan–Meier Estimates of Cumulative Active Vancomycin Therapy Before and After Implementation of Nasal MRSA PCR protocol
Figure 2. Secondary Outcome: Figure 2. Kaplan–Meier Estimates of Cumulative Active Vancomycin Therapy in Patients with Negative vs Positive Nasal MRSA PCR


Conclusion: Pharmacist-driven nasal MRSA PCR testing is effective and safe in early de-escalation of empiric vancomycin used for pneumonia treatment in a diverse population including critically ill and immunocompromised patients.