833. Accelerated Availability of Identification and Antimicrobial Susceptibility Results Using the KeyPath MRSA/MSSA Blood Culture Test
Session: Oral Abstract Session: Advances in Diagnostics
Saturday, October 22, 2011: 9:00 AM
Room: 151AB
Background: Improved patient outcomes for S. aureus bacteremia are associated with early adoption of appropriate antibiotic therapy.  The KeyPath MRSA/MSSA Blood Culture Test is capable of identifying S. aureus in positive blood cultures and determining phenotypic resistance or susceptibility to cefoxitin in 5 hours without the need for instrumentation.  We compared the time to availability of bacterial identification and antimicrobial susceptibility test (AST) results using this method to standard culture results in a multicenter clinical trial. 

Methods: The KeyPath MRSA/MSSA Blood Culture Test - BT was performed on positive BACTEC blood cultures according to the manufacturer’s protocol.  Site microbiology was performed according to each institutions standard protocol, and consisted of organism isolation followed by automated identification and AST on either a Microscan or Vitek II.  The times of blood culture positivity, Gram-stain results, KeyPath results and microbiology results were recorded.  Apparent transcription errors (eg., Gram-stain results before blood culture positivity results) were excluded, and the data were analyzed for means, medians and variation.

Results: The median time to availability of 708 KeyPath ID/AST results was 16.9 hours after Gram-stain, with 95% of results available in the interval 4.7 – 29.3 hours.  The range of medians between sites was 13.4 – 20.9 hours. The median time to availability of 706 standard microbiology ID/AST results was 46.9 hours after Gram-stain, with 95% of results available in the interval 11.5 – 131.7 hours.  The range of medians between sites was 21.8 – 67.3 hours.

Conclusion: The KeyPath MRSA/MSSA Blood Culture Test – BT has been shown to be >99% accurate in determining methicillin resistance or susceptibility among positive S. aureus blood cultures.  Despite the limitation of being run on a single shift, vs 2 or 3 shifts for standard culture work-up, the KeyPath Test was able to return actionable identification and AST results a median of 30 hours sooner than conventional methods.  The accelerated availability of these results should decrease the time required to institute appropriate antibiotic therapy, possibly resulting in better patient outcomes and reduced length of stay.



Subject Category: D. Diagnostic microbiology

Thomas Kirn, MD PhD1, Tanaya Bhowmick, MD1, Stanley Mirrett, MS2, Connie Price, MD3,4, Barth Reller, MD2, Drew Smith, PhD5 and Melvin Weinstein, MD, FIDSA1, (1)Robert Wood Johnson Medical School, New Brunswick, NJ, (2)Duke University Medical Center, Durham, NC, (3)Denver Health Medical Center, Denver, CO, (4)University of Colorado Health Sciences Center, Denver, CO, (5)MicroPhage Inc, Longmont, CO

Disclosures:

T. Kirn, MicroPhage Inc: Grant Investigator, Research support

T. Bhowmick, None

S. Mirrett, MicroPhage Inc: Investigator, Research support

C. Price, MicroPhage Inc: Investigator, Research support

B. Reller, MicroPhage Inc: Investigator, Research support

D. Smith, MicroPhage Inc: Employee, Salary

M. Weinstein, MicroPhage Inc: Investigator, Research support

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.