# P-800. Pharmacist-driven Methicillin-resistant Staphylococcus aureus Nasal Polymerase Chain Reaction (PCR) Screening in Multi-hospital System Reduced Resistant Gram-positive Antibiotics Use and Standardized Antimicrobial Administration Ratio (SAAR)

## TL;DR

Pharmacists ordering MRSA PCR tests helped reduce antibiotic use for resistant infections in a multi-hospital system.

## Contribution

Pharmacist-led MRSA PCR screening significantly reduced antibiotic use for resistant gram-positive infections in a multi-hospital system.

## Key findings

- SAAR for resistant gram-positive agents decreased by 20.2% after implementing pharmacist-driven MRSA PCR screening.
- DOTs/1000 days present for resistant gram-positive agents dropped from 88 to 63 following the intervention.
- ICU SAARs decreased by 31.2% after the program was implemented.

## Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) testing, with known high specificity and negative predictive value, is particularly effective in ruling out MRSA pneumonia. There is significant potential to enhance antimicrobial stewardship efforts and optimize use of antibiotics for resistant gram-positive infections, especially when implemented and monitored in an evidence-based, comprehensive manner. In early 2023, health-system hospitals in Southeast Michigan authorized pharmacists to order MRSA nasal PCR swabs per protocol. This study aimed to investigate the impact of MRSA nasal PCR introduction combined with pharmacist active monitoring and intervention on the utilization of antibiotics for resistant gram-positive infections.Figure 1.Resistant Gram-positive Agent Standardized Antimicrobial Administration RatiosBar graph comparing Standardized Antimicrobial Administration Ratios (SAARs) for resistant gram-positive agents pre- and post-initiation of pharmacy-driven MRSA PCR nasal screening

Resistant Gram-positive Agent Standardized Antimicrobial Administration Ratios

Bar graph comparing Standardized Antimicrobial Administration Ratios (SAARs) for resistant gram-positive agents pre- and post-initiation of pharmacy-driven MRSA PCR nasal screening

This multi-center, retrospective pre-post, cohort study evaluated utilization of antibiotics for resistant gram-positive infections in a multi-hospital health-system in Michigan. Cohorts were compared prior to (January 2021 to December 2022) and following MRSA PCR testing rollout (January 2023 to December 2024). Changes in resistant gram-positive agent days of therapy (DOTs) per 1,000 days present and Standardized Antimicrobial Administration Ratio (SAAR) data were evaluated between cohorts at the facility and patient care unit levels.

There was a significant decrease in resistant gram-positive agent utilization between cohorts demonstrated by a 20.2% decrease in SAAR (0.893 vs. 0.697; P < 0.001) (Figure 1). This resulted in a reduction of 8,124 DOTs over predicted historical use. Similarly, DOTs/1,000 days present decreased (88 DOTs/1000 days present vs. 63 DOTs/1000 days present; P < 0.001). All hospitals showed significant SAAR reductions and seventeen of 23 patient care units across all hospitals demonstrated significant SAAR decreases. This included a 31.2% decrease in SAARs in the intensive care units (0.988 vs. 0.68; P < 0.001).

MRSA nasal PCR introduction combined with pharmacist active monitoring and intervention significantly improved utilization of resistant gram-positive agents across a multi-hospital health-system.

All Authors: No reported disclosures