Background: Methicillin- resistant Staphylococcus aureus (MRSA) nasal Polymerase Chain Reaction (PCR) screening is an evidenced based diagnostic tool that can guide decisions regarding the need for anti-MRSA therapy. This evaluation aims to assess the correlation between positive nasal PCR results and culture confirmed Staphylococcus aureus infections. The utility of this screening method will be assessed for skin and soft tissue infections (SSTIs), bacteremia, wound, and urine cultures. These findings may help determine if the use of nasal PCR can be expanded beyond pneumonia to serve as a tool for guiding antimicrobial therapy in suspected MRSA infections at our institution.
Methods: This is a single-center, retrospective study conducted at a 312-bed academic teaching hospital. Hospitalized patients 18 years of age and older who had a positive nasal PCR screening with a corresponding blood, urine, and wound culture outcomes. The primary outcome is to evaluate whether nasal PCR screening demonstrates a predictive value in relation to culture-confirmed Staphylococcus aureus infections. The data will be grouped for each set of cultures and will determine a negative predictive value. The study protocol is designated exempt from review by the Hospital Corporation of America (HCA) Institutional Review Board (IRB).
Results: Based on the blood, urine, and wound culture data, the wound data had the greatest negative predictive value. Overall, 1000 patients were screened, 495 patients were excluded due to the lack of additional body sources. Out of the 505 patients, 52 were excluded due to lacking a blood, urine, or wound culture. There were 453 patients that were then included overall in the data collection. Blood cultures had a negative predictive value of 68.5%, urine cultures 66.1%, and wound cultures 76.2%.
Conclusion: Based on the results from our institution there is correlation that having a negative MRSA Nasal PCR would likely result in negative MRSA/MSSA blood, wound, or urine cultures. The highest NPV was for wound cultures at 76.2%. Further research is needed to assess a larger population and potential impact of antimicrobial agents initiated prior to MRSA Nasal PCR for future studies.
