Antibiotic de-escalation in pneumonia with pharmacist education and ordering of methicillin-resistant Staphylococcus aureus nasal swabs.

Introduction: When methicillin-resistant Staphylococcus aureus (MRSA) is the causative pathogen in pneumonia, in-hospital mortality rate is approximately 31.2%. However, the occurrence of MRSA pneumonia is uncommon, with a reported incidence of approximately 4.2%. Vancomycin is often empirically used for MRSA pneumonia coverage, but can lead to serious harm. The purpose of this study was to measure the impact of a pharmacy-driven MRSA nares testing protocol on vancomycin and linezolid prescribing patterns and clinical outcomes in patients diagnosed with pneumonia after removal of immediate educational intervention.

Methods: This single-centre, quasi-experimental study evaluated the use of a MRSA nasal swab on patients diagnosed with community-acquired pneumonia, hospital-acquired pneumonia and ventilator-associated pneumonia. This study consisted of three phases, the preimplementation phase, the active/educational phase and the postimplementation phase. The primary outcome was intravenous anti-MRSA antibiotic duration of therapy. Secondary outcomes included the occurrence of acute kidney injury, duration of hospital stay, number of vancomycin levels obtained, the number of MRSA nares swabs ordered and time points in the MRSA nares collection process.

Results: The preimplementation phase (n=39), the active phase (n=45) and the postimplementation phase (n=26) demonstrated similar baseline characteristics. The primary outcome for duration of anti-MRSA therapy 0-72 hours was 61.5% vs 77.8% vs 76.9% (p=0.19). Acute kidney injury was decreased throughout the study at 25.6%, 24.4% and 16.7% (p=0.32). The number of MRSA nares swabs ordered were 23.1%, 60% and 30.8% in each of the phases, respectively (p=0.49).

Discussion: Our novel approach to measuring the impact of pharmacist education and ordering of MRSA nasal swabs has demonstrated benefits that were sustained for a short period after the intervention was removed. Additional study is required to determine the long-term impact.

Conclusion: The implementation of a hospital-wide anti-MRSA protocol in patients with confirmed or suspected pneumonia indicated sustained changes for at least 3 months after direct intervention.