Rapid Identification and Susceptibility Testing of Pathogens From Blood Cultures

Difference between the date and time of the antibiotic start order (or Gram stain-positive blood culture, if antibiotics were started prior to the positive culture result) and the date and time of the antibiotic stop order. Shorter duration of broad spectrum antibiotics and longer duration of narrow-spectrum antibiotics were considered favorable outcomes.

From positive Gram stain to start of active antibiotic among patients not on active therapy at enrollment; excludes subjects with contaminated blood cultures.

De-escalation included discontinuation of 1 or more antibiotics and/or switching from a broad- to a narrow spectrum antibiotic. Escalation included initiation of 1 or more antibiotics and/or switching from a narrow- to a broad-spectrum antibiotic.

Contaminated blood cultures were defined as growth of organisms such as coagulase-negative staphylococci from a single blood culture set when greater than or equal to 2 blood culture sets were collected, except among subjects suspected to have true bacteremia associated with central venous catheters or devices.

If records of death were incomplete, mortality was determined using Accurint (LexisNexis, Philadelphia, PA), an internet research and location service.

This included all adverse events that occurred within 2 weeks following enrollment and were documented in the medical record.

Costs were calculated using a standardized inflation-adjusted estimate of costs for each service or procedure performed in constant dollars. This approach adjusts for hospital-billed charges with Medicare Cost Report department-level cost-to-charge ratios. Physician services were proxied with Medicare reimbursement rates based on Current Procedure Terminology (CPT)-4 codes using the Medicare Fee Schedule. We did not include the cost of the stewardship program in the cost analysis, as it is not a billed service. As there was no Medicare reimbursement rate for the rmPCR test at the time of the study, test cost was proxied using the FilmArray respiratory panel. These costs were varied in sensitivity analysis with rmPCR test cost ranging from a 50% decrease to a 300% increase.

Multidrug-resistant organisms included vancomycin-resistant enterococci, methicillin-resistant Staphylococcus aureus, extended-spectrum cephalosporin-resistant Enterobacteriaceae, and Pseudomonas aeruginosa and Acinetobacter species resistant to greater than or equal to 3 antibiotic classes.