Evaluation of the QMAC‐dRAST System Version 2.5 for Rapid Antimicrobial Susceptibility Testing of Gram‐Negative Bacteria From Positive Blood Culture Broth and Subcultured Colony Isolates

• Published in: Journal of clinical laboratory analysis Vol. 38; no. 9; pp. e25043 - n/a
• Main Authors: Kim, Tae Yeul, Kang, Minhee, Shim, Hyang Jin, Kang, On‐Kyun, Huh, Hee Jae, Lee, Nam Yong
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.05.2024; John Wiley and Sons Inc
• Subjects: Agreements; Anti-Bacterial Agents - pharmacology; Antibiotics; Antimicrobial agents; Antimicrobial resistance; antimicrobial susceptibility testing; Automation; Bacteria; Blood culture; Blood Culture - methods; bloodstream infections; broth microdilution; Carbapenemase; Carbapenems; Clinical isolates; Clinical outcomes; Colonies; Data analysis; E coli; Gram-negative bacteria; Gram-Negative Bacteria - drug effects; Gram-Negative Bacteria - isolation & purification; Gram‐negative; Humans; Microbial Sensitivity Tests - methods; Microfluidics; Performance evaluation; positive blood culture broth; QMAC‐dRAST; Sepsis; Test methods; VITEK 2; VITEK 2; bloodstream infections; antimicrobial susceptibility testing; Gram‐negative; broth microdilution; antimicrobial resistance; QMAC‐dRAST; positive blood culture broth
• ISSN: 0887-8013; 1098-2825; 1098-2825
• DOI: 10.1002/jcla.25043

ABSTRACT Background Rapid antimicrobial susceptibility testing (AST) for bloodstream infections (BSIs) facilitates the optimization of antimicrobial therapy, preventing antimicrobial resistance and improving patient outcomes. QMAC‐dRAST (QuantaMatrix Inc., Korea) is a rapid AST platform based on microfluidic chip technology that performs AST directly using positive blood culture broth (PBCB). This study evaluated the performance of QMAC‐dRAST for Gram‐negative bacteria using PBCB and subcultured colony isolates, comparing it with that of VITEK 2 (bioMérieux, France) using broth microdilution (BMD) as the reference method. Methods We included 141 Gram‐negative blood culture isolates from patients with BSI and 12 carbapenemase‐producing clinical isolates of Enterobacterales spiked into blood culture bottles. QMAC‐dRAST performance was evaluated using PBCB and colony isolates, whereas VITEK 2 and BMD were tested only on colony isolates. Results For PBCB, QMAC‐dRAST achieved 92.1% categorical agreement (CA), 95.3% essential agreement (EA), with 1.8% very major errors (VMEs), 3.5% major errors (MEs), and 5.2% minor errors (mEs). With colony isolates, it exhibited 92.5% CA and 95.1% EA, with 2.0% VMEs, 3.2% MEs, and 4.8% mEs. VITEK 2 showed 94.1% CA and 96.0% EA, with 4.3% VMEs, 0.4% MEs, and 4.3% mEs. QMAC‐dRAST yielded elevated error rates for specific antimicrobial agents, with high VMEs for carbapenems and aminoglycosides. The median time to result for QMAC‐dRAST was 5.9 h for PBCB samples and 6.1 h for subcultured colony isolates. Conclusions The QMAC‐dRAST system demonstrated considerable strengths and comparable performance to the VITEK 2 system; however, challenges were discerned with specific antimicrobial agents, underlining a necessity for improvement. The flowchart depicting the performance evaluation of QMAC‐dRAST version 2.5 in our study. BMD, broth microdilution; CA, categorical agreement; EA, essential agreement; ME, major error; mE, minor error; PBCB, positive blood culture broth; VME, very major error.