Performance Evaluation of the Quantamatrix QMAC-dRAST System for Rapid Antibiotic Susceptibility Testing Directly from Blood Cultures

Abstract

Objectives: Rapid antibiotic susceptibility testing (AST) for positive blood cultures can improve patient clinical outcomes if the time to an effective antimicrobial therapy is shortened. In this study, we tested the Quantamatrix dRAST system (QMAC-dRAST), a rapid AST system based on time-lapse microscopic imagery of bacterial colony formation in agarose. Methods: Evaluation of the QMAC-dRAST was performed from 250 monobacterial blood cultures including 130 Enterobacterales, 20 non-fermentative Gram-negative bacteria, 69 staphylococci and 31 enterococci. Blood cultures were recovered from anonymous patients or from spiking experiments to enrich our study with bacterial species and resistant strains. Categorical agreement (CA), minor errors (me), major errors (ME) and very major errors (VME) were calculated in comparison to the results obtained from the BD Phoenix™ M50. Discrepancies between the Phoenix™ M50 and QMAC-dRAST results were investigated using the gradient strip method. The repeatability and reproducibility performance of the QMAC-dRAST was assessed for 16 strains, each strain being tested five times from a spiked blood culture. Results: The overall CAs for Enterobacterales, non-fermentative Gram-negative bacteria, staphylococci and enterococci were 95.1%, 91.2%, 93.4% and 94.5%, respectively. The VME percentage was below 4% for all the groups except for staphylococci, which showed a VME rate of 7%. The median time to result was 6.7 h (range: 4.7–7.9). Repeatability and reproducibility assays showed a high reliability of AST results with best and worst ratios of 98.8% and 99.6% and 95.0% and 98.3%, respectively. Conclusions: The QMAC-dRAST is a fast and reliable system to determine AST directly from monobacterial blood cultures with a major TAT reduction compared to conventional AST testing.

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

“…First, high ME rates were noted for cefepime, ceftazidime, and piperacillin–tazobactam, which were most evident in P. aeruginosa strains. These results are consistent with performances reported in previous studies [ 19 , 22 , 28 ]. Second, despite CAs exceeding 95%, Enterobacterales exhibited high VME rates for aminoglycosides, specifically amikacin and gentamicin, aligning with previous findings [ 14 , 17 , 21 ].…”

“…Although rapid phenotypic AST methods have not demonstrated a significant reduction in mortality in most studies [ 15 , 16 ], they have the potential to shorten the time to optimal therapy and improve antibiotic stewardship in patients with bloodstream infections [ 10 ]. The QMAC‐dRAST system provides rapid results and may be a promising alternative to conventional AST methods [ 7 , 17 , 18 , 19 , 20 , 21 ]. Previous versions of QMAC‐dRAST required 6 h of incubation, excluding the time for preincubation preparation, imaging, or reporting [ 18 , 22 ].…”

“…Lastly, the QMAC‐dRAST system exhibited a less favorable performance with carbapenems, resulting in a lower CA for meropenem, and most errors were classified as VMEs for ertapenem and imipenem. Despite previous studies evaluating the performance of QMAC‐dRAST for GNB, such findings have not yet been fully described, likely because these previous studies included minimum to no carbapenem‐resistant (CR) GNB [ 17 , 19 , 30 , 31 ]. The escalation in the global prevalence of CRGNB, including CPE, poses substantial threats to public health and emphasizes the importance of rapid and accurate detection of carbapenem resistance [ 32 , 33 , 34 ].…”

Antimicrobial Multidrug Resistance: Clinical Implications for Infection Management in Critically Ill Patients

“…One ongoing pre/post quasi-experimental study will evaluate its clinical impact on empirical antimicrobial therapy (NCT NCT05741424); in addition, one RCT will determine the benefit of the BCID2 associated with the REVEAL ® automated system for antimicrobial prescription and de-escalation (NCT05909683). dRAST Another rapid AST system, the dRAST system (QuantaMatrix Inc., Seoul, Korea), showed fast and reliable susceptibility testing directly on monobacterial blood cultures with a major turnaround time reduction (median turnaround time: 6.7 h (range: 4.7-7.9)) [88][89][90][91]. The technique is based on a microfluidic agarose channel system that immobilizes the bacteria in agarose-containing microfluidic chambers.…”

A multisite validation of a two hours antibiotic susceptibility flow cytometry assay directly from positive blood cultures

“…Recent approaches have been introduced with the capacity to detect early bacterial growth such as the Accelerate Pheno [ 14 ], the QuickMIC [ 15 ], ASTar system [ 16 ], Quantamatrix [ 17 ] or Specific Reveal [ 18 ] methods. All of them are growth-dependent like standard AST, taking in general 5–8 h to provide results, depending on the microorganism and/or phenotype; it is faster to determine resistance than susceptibility on those kind of growth-base assays.…”