Comparison of Methicillin-Resistant Staphylococcus aureus Nasal Screening Predictive Value in the Intensive Care Unit and General Ward

Abstract

Background: The clinical utility of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening appears promising for antimicrobial stewardship programs. However, a paucity of data remains on the diagnostic performance of culture-based MRSA screen in the intensive care unit (ICU) for pneumonia and bacteremia. Objective: The objective of this study was to compare the predictive value of culture-based MRSA nasal screening for pneumonia and bacteremia in ICU and general ward patients. Methods: This multicenter, retrospective study was conducted over a 23-month period. Adult patients with MRSA nasal screening ≤48 hours of collecting a respiratory and/or blood culture with concurrent initiation of anti-MRSA therapy were included. The primary endpoint was to compare the negative predictive value (NPV) associated with culture-based MRSA nasal screening between ICU and general ward patients with suspected pneumonia. Results: A total of 5106 patients representing the ICU (n = 2515) and general ward (n = 2591) were evaluated. The NPV of the MRSA nares for suspected pneumonia was not significantly different between ICU and general ward patient populations (98.3% and 97.6%, respectively; P = 0.41). The MRSA nares screening tool also had a high NPV for suspected bacteremia in ICU (99.8%) and general ward groups (99.7%) ( P = 0.56). The overall positive MRSA nares rates in the ICU and general ward patient populations were 9.1% and 8.2%, respectively ( P = 0.283). Moreover, MRSA-positive respiratory and blood cultures among ICU patients were 5.8% and 0.8%, respectively. Conclusion and Relevance: Our findings support the routine use of MRSA nasal screening using the culture-based method in ICU patients with pneumonia. Further research on the clinical performance for MRSA bacteremia in the ICU is warranted.

Swab Testing to Optimize Pneumonia treatment with empiric Vancomycin (STOP-Vanc): study protocol for a randomized controlled trial.

“…While this means a greater likelihood of unnecessary vancomycin use, it is also possible that there is greater hesitancy to discontinue vancomycin based on the results of the MRSA PCR testing alone. Retrospective studies looking at the use of nasal swab-based screening for MRSA colonization have found that the test maintains a high NPV in multiple ICU settings [28][29][30][31][32]. A prospective antibiotic de-escalation study found that an intervention based on negative MRSA nasal cultures decreased anti-MRSA antibiotic use in an ICU [22].…”