title: Clinical utility of methicillin-resistant Staphylococcus aureus nasal polymerase chain reaction assay in critically ill patients with nosocomial pneumonia.
abstract: This study investigated the diagnostic performance characteristics of a methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction (PCR) assay in critically ill patients with nosocomial pneumonia.
  
  
  
  This retrospective, single-center study included adult patients admitted to an intensive care unit with suspected nosocomial pneumonia. Patients must have received an MRSA nasal PCR assay and respiratory culture within predetermined time intervals. The primary outcome included the diagnostic performance characteristics of the assay. Secondary outcomes included the change in negative predictive value (NPV) over time, rate of acute kidney injury, and cost avoidance associated with vancomycin and monitoring.
  
  
  
  In 400 patients meeting inclusion criteria, the prevalence of culture confirmed MRSA pneumonia was 9.3%. When compared to initial cultures, the PCR assay demonstrated 91.89% sensitivity and 84.3% specificity with a positive predictive value and NPV of 37.36% and 99.03%. The NPV decreased to 87.5% at 21.9 days. No difference was found in rates of acute kidney injury. A cost avoidance of $108 per patient was estimated in patients de-escalated based on negative results.
  
  
  
  In critically ill patients, an MRSA nasal PCR assay has a high NPV for nosocomial pneumonia and can be used to guide vancomycin de-escalation.
authors.affiliation: UF Health Jacksonville, Jacksonville, FL, 32209. Electronic address: mnsmith0204@gmail.com.
authors.forename: Melanie N
authors.initials: MN
authors.lastname: Smith
authors.affiliation: UF Health Jacksonville, Jacksonville, FL, 32209. Electronic address: michael.erdman@jax.ufl.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Erdman
authors.affiliation: UF Health Jacksonville, Jacksonville, FL, 32209. Electronic address: jason.ferreira@jax.ufl.edu.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Ferreira
authors.affiliation: UF Health Jacksonville, Jacksonville, FL, 32209. Electronic address: petra.aldridge@jax.ufl.edu.
authors.forename: Petra
authors.initials: P
authors.lastname: Aldridge
authors.affiliation: UF Health Jacksonville, Jacksonville, FL, 32209. Electronic address: christopher.jankowski@jax.ufl.edu.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Jankowski
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003422:Critical Care; D016638:Critical Illness; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D005431:Florida / Q000453:epidemiology; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobial stewardship; Critically ill; MRSA; Negative predictive value; Pneumonia; Polymerase chain reaction