C A Hogan1, N Watz2, I Budvytiene2, N Banaei3. 1. Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA; Clinical Microbiology Laboratory, Stanford University Medical Center, Palo Alto, CA, USA. 2. Clinical Microbiology Laboratory, Stanford University Medical Center, Palo Alto, CA, USA. 3. Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA; Clinical Microbiology Laboratory, Stanford University Medical Center, Palo Alto, CA, USA; Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. Electronic address: nbanaei@stanford.edu.
Abstract
OBJECTIVE: Optimizing therapy for bacteremia is currently limited by the 1-2-day turnaround time required for antimicrobial susceptibility testing (AST). Here, we assess a rapid AST method with VITEK®2 (bioMérieux, France) directly from positive blood cultures. METHODS: Patient-derived positive blood cultures with Gram-negative rods identified as Enterobacteriaceae and Pseudomonas aeruginosa were prospectively tested, and other blood culture bottles were spiked with carbapenem-resistant Enterobacteriaceae (CRE). Positive cultures were subjected to red blood cell lysis and centrifugation, and setup on VITEK®2. RESULTS: A total of 109 patient blood cultures and 52 spiked blood cultures were tested. Overall, essential agreement was 97.7% [95% confidence interval (CI) 96.4-99.0], and categorical agreement was 96.8% (95% CI 95.0-98.6). Mean turnaround time from setup to susceptibility results for Enterobacteriaceae in the clinical cultures was 9.0 (±1.3) h. CONCLUSIONS: Direct susceptibility testing of blood cultures by VITEK®2 for Enterobacteriaceae is an accurate, practical, and inexpensive diagnostic strategy for rapid automated AST.
OBJECTIVE: Optimizing therapy for bacteremia is currently limited by the 1-2-day turnaround time required for antimicrobial susceptibility testing (AST). Here, we assess a rapid AST method with VITEK®2 (bioMérieux, France) directly from positive blood cultures. METHODS:Patient-derived positive blood cultures with Gram-negative rods identified as Enterobacteriaceae and Pseudomonas aeruginosa were prospectively tested, and other blood culture bottles were spiked with carbapenem-resistant Enterobacteriaceae (CRE). Positive cultures were subjected to red blood cell lysis and centrifugation, and setup on VITEK®2. RESULTS: A total of 109 patient blood cultures and 52 spiked blood cultures were tested. Overall, essential agreement was 97.7% [95% confidence interval (CI) 96.4-99.0], and categorical agreement was 96.8% (95% CI 95.0-98.6). Mean turnaround time from setup to susceptibility results for Enterobacteriaceae in the clinical cultures was 9.0 (±1.3) h. CONCLUSIONS: Direct susceptibility testing of blood cultures by VITEK®2 for Enterobacteriaceae is an accurate, practical, and inexpensive diagnostic strategy for rapid automated AST.
Authors: Alyssa B Christensen; Brent Footer; Tobias Pusch; Kim Heath; Maha Iqbal; Lian Wang; Gregory Tallman; Cameron Cover; Jennifer Marfori; Brian Kendall; Nick Stucky; Meagan Greckel; Ivor L Thomas; Katelynn Tran; Salena Yip; Margret Oethinger Journal: Open Forum Infect Dis Date: 2022-07-22 Impact factor: 4.423