The Impact of MRSA PCR Screening on Vancomycin De-escalation in Critically Ill Surgical Patients

Author(s):
Hannah Megison; Jared Robinson; Lillian Bellfi; Juan Duchesne; Patrick McGrew; John P Hunt; Lance E Stuke MD, MPH Stuke MD, MPH; Patrick Greiffenstein; Jonathan Schoen; Alan Marr; Alison Smith

Background:

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in the healthcare setting represents a significant healthcare risk for critically ill patients. Vancomycin is the empiric treatment for MRSA and entails significant toxicity. Polymerase chain reaction (PCR) nares swabs offer a rapid, high negative predictive value allowing for expedited de-escalation of vancomycin. The utility of this screening tool remains unexplored in critically ill surgical patients, which are highly susceptible to hospital-acquired infections. The objective of this study was to assess the impact of empiric MRSA PCR nares screening on vancomycin therapy de-escalation in this vulnerable population.

Hypothesis:

The implementation of rapid PCR screening for MRSA colonization in the nares of critically ill surgical patients admitted to the intensive care unit (ICU) will lead to a significant reduction in the duration of empiric vancomycin therapy, without adversely affecting patient outcomes including ICU/hospital length of stay (LOS) and mortality.

Methods:

A single-center pre-post observational cohort study at a Level I trauma center was performed over a one-year period. Adult patients admitted to the surgical ICU receiving empiric vancomycin were included. Patients were categorized into pre-cohort and post-cohort, representing hospital admission dates that occurred six month before and six months after the implementation of rapid MRSA PCR nares screening, respectively. Descriptive statistics, non-parametric Wilcoxon two-sample tests, and Chi-square analyses were performed. The primary outcome was vancomycin therapy duration. Secondary outcomes included ICU/hospital LOS and mortality.

Results:

A total of 239 patients were analyzed with 132 in the pre-cohort and 107 in the post-cohort. Baseline demographics were comparable (p>0.05). There was a decrease in vancomycin days in the post-cohort group compared to the pre-cohort group (2.84 vs. 4 days, p<0.05). MRSA PCRs were ordered in 74% of post-cohort patients versus 19% in the pre-cohort (p<0.05). No significant differences were found in ICU/hospital LOS or mortality (p>0.05).

Conclusions:

The study demonstrates a marked reduction in vancomycin therapy duration post-MRSA PCR implementation. These results highlight the utility of MRSA PCR in optimizing antibiotic stewardship, mitigating vancomycin-associated toxicity, and addressing antibiotic resistance in critical care surgical patients. Further research is needed to explore long-term implications and integrate PCR-based strategies into antibiotic stewardship initiatives in larger cohorts.