Performance of nasal methicillin‐resistant Staphylococcus aureus screening for intra‐abdominal infections in critically ill adult patients

Abstract

Study Objective Intra‐abdominal infections (IAIs) are a common reason for intensive care unit (ICU) admissions, and methicillin‐resistant Staphylococcus aureus (MRSA) is an uncommon pathogen in IAIs. Although more data are available in the setting of non‐abdominal sources, there are limited data on the performance of nasal MRSA screening for MRSA IAIs. The primary objective of this study was to evaluate the performance of nasal MRSA screening for MRSA IAIs in critically ill adult patients. Design This was a multicenter, retrospective, cohort study. Setting A 14‐hospital healthcare system between January 1, 2014, and August 31, 2019. Patients Adult patients admitted to an ICU for at least 24 h with a diagnosis code for an IAI, a nasal MRSA surveillance screen within 30 days, and an intra‐abdominal culture were eligible for inclusion. Intervention The primary outcome was to evaluate the performance of nasal MRSA screening for MRSA IAIs by calculating the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Measurements and Main Results Out of 863 patients randomly screened, a total of 192 patients were included. The study population had a mean age of 60 (SD ±15) years, and 101 (53%) patients were male. Six (3.1%) patients were positive for an MRSA IAI, of which four (66.7%) demonstrated a positive nasal MRSA screen. A total of 186 (96.8%) patients were negative for a MRSA IAI, of which 19 (10.2%) were nasal MRSA‐positive and 167 (89.8%) were nasal MRSA‐negative. Nasal MRSA screening demonstrated the following performance: accuracy 89.1% (95% CI: 83.8%–93.1%), sensitivity 66.7% (95% CI: 22.3%–95.7%), specificity 89.8% (95% CI: 84.5%–93.7%), PPV 17.4% (95% CI: 9.4%–30.0%), and NPV 98.8% (95% CI: 96.4%–99.6%). There were no significant differences in clinical outcomes, including renal replacement‐free days, ICU and hospital length of stay, and in‐hospital mortality. Conclusions Among critically ill adult patients with IAIs, a negative nasal MRSA screen within 30 days may help to empirically exclude MRSA as a causative pathogen.

Performance of Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction Nasal Screening for Ruling Out MRSA Pneumonia in Hospitalized, Immunocompromised Patients

“…8,9,11 Immunocompromised patients were included in a study evaluating NPV for MRSA NaPCR in intra-abdominal infections and in pharmacistdriven MRSA surveillance protocols, although the criteria for immunocompromise in these studies were not defined, and the population was limited to less than 30 patients. [12][13][14] To optimize antimicrobial utilization in immunocompromised patients, a population that has increased risk for infections and sees frequent antibiotic use, it is crucial to better describe the NPV of MRSA NaPCR in this patient population. 15 The objective of this study was to determine the NPV of the MRSA NaPCR screening tool in hospitalized, immunocompromised patients for ruling out MRSA pneumonia.…”