RESEARCH ARTICLE
Performance of QMAC-dRASTTM (Direct Rapid Antimicrobial Susceptibility Testing) - a Newcomer in Phenotypic Automatic AST
Jens J. Christensen1, 2, *, Hanne Junker1, Connie B. Madsen1, Camilla F. Christiansen1, Tina Kristensen1, Tine K. Lund1, Majbritt Fallesen1, Rie Kjølsen1, Bodil Hansen1, Pia K. Hansen1, Ulrich S. Jensen1
Article Information
Identifiers and Pagination:
Year: 2021Volume: 15
First Page: 43
Last Page: 50
Publisher ID: TOMICROJ-15-43
DOI: 10.2174/1874285802115010043
Article History:
Received Date: 22/9/2020Revision Received Date: 31/1/2021
Acceptance Date: 04/2/2021
Electronic publication date: 19/04/2021
Collection year: 2021
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Objective:
QMAC-dRASTTM is a phenotypic automatized Antibiotic Susceptibility Testing (AST) system based on microfluidic chip technology enabling observation of changes in a single bacterial cell under antibiotic treatment conditions. The 96 wells plate with dried antibiotics comprises 19 and 17 antibiotics for the Gram-Negatives (GNs) and Gram-Positives (GPs), respectively. Categorical (Sensitive, Intermediate or Resistant) results were compared to results obtained by our laboratory standard susceptibility testing procedure and given as Categorical Agreement (CA).
Methods:
In a 3-month period (2019/2020), blood cultures detected positive were included. Excluded were known off-panel strains of QMAC-dRASTTM, such as Gram-positive bacilli, Streptococcus and Candida species. Percentages of CA (CA, %) between QMAC-dRASTTM and routine testing methods used in the laboratory (EUCAST disc diffusion and/or etest/Broth Micro Dilution MIC), were calculated.
Results:
255 positive blood cultures from as many patients were examined. Of the positive blood culture strains, 144 were GNs, and 111 were GPs. An overall combined CA,% of 96.3 (2410 of 2502 determinations) was obtained, and discrepancies were noted in 92 of 2502 test results (3.7%). The percentage of very major errors (VMEs) was 0.7% for GNs and 2.2% for GPs. For 87% of blood culture specimens examined, susceptibility reports were available within 6-7 hours.
Conclusion:
The high CA,% for as well GNs as GPs are promising. The presented time to report data obtained by QMAC-dRASTTM in this study being of 3-8 hours for blood culture specimens examined strongly support a further possible improvement in the workflow for handling blood stream infections.
