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Purpose To determine the impact of a pharmacist-driven methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) screen on vancomycin duration in critically ill patients with suspected pneumonia. Methods This was a retrospective, quasi-experimental study at a 613-bed academic medical center with 67 intensive care beds. Adult patients admitted to the intensive care unit (ICU) between 2017 and 2019 for 24 hours or longer and empirically started on intravenous vancomycin for pneumonia were included. The primary intervention was the implementation of a MRSA nasal PCR screen protocol. The primary outcome was duration of empiric vancomycin therapy. Secondary outcomes included the rate of acute kidney injury (AKI), the number of vancomycin levels obtained, the rate of resumption of vancomycin for treatment of pneumonia, ICU length of stay, hospital length of stay, the rate of ICU readmission, and the rate of in-hospital mortality. Results A total of 418 patients were included in the final analysis. The median vancomycin duration was 2.59 days in the preprotocol group and 1.44 days in the postprotocol group, a reduction of approximately 1.00 day (P < 0.01). There were significantly fewer vancomycin levels measured in the postprotocol group than in the preprotocol group. Secondary outcomes were similar between the 2 groups, except that there was lower AKI and fewer vancomycin levels obtained in the postprotocol group (despite implementation of area under the curve–based vancomycin dosing) as compared to the preprotocol group. Conclusion The implementation of a pharmacist-driven MRSA nasal PCR screen was associated with a decrease in vancomycin duration and the number of vancomycin levels obtained in critically ill patients with suspected pneumonia.

A pharmacist-driven MRSA nasal PCR-based testing protocol with a 70% acceptance rate for vancomycin discontinuation within 24 hours of negative results significantly reduced unnecessary vancomycin use with an estimated cost avoidance of $40 per vancomycin course. We found high concordance (141/147, 96%) of culture-based vs PCR-based MRSA nasal screening.

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. Disclosures All Authors: No reported disclosures