Comparison of the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for routine antimicrobial disc diffusion susceptibility testing

Abstract

Objectives: This study investigated the agreement at the categorical level between the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for antimicrobial disc diffusion susceptibility testing. Methods: The 338 clinical strains (67 Pseudomonas aeruginosa, 19 methicillin-resistant Staphylococcus aureus, 75 methicillin-sensitive S. aureus and 177 Enterobacterales isolates) analysed in this study were non-duplicate isolates obtained from consecutive clinical samples referred to the clinical bacteriology laboratory at Geneva University Hospitals between June and August 2019. For the WASPLab the inoculum suspension was prepared in strict accordance with the manufacturer's instruction (Copan WASP srl, Brescia, Italy) by adding 2 mL of the 0.5 McFarland primary suspension used for the SIRscan analysis into a sterile tube filled with 4 mL of sterile saline (1:3 dilution). The inoculum (2 Â 30 mL loop/spreader) was spread over the entire surface of MuellereHinton agar plates according to the AST streaking pattern defined by Copan. The antibiotic discs were dispensed by the WASP and inoculated media were loaded on conveyors for transfer to the automatic incubators. The plates were incubated for 16 h, and several digital images were acquired. Inhibition zone diameters were automatically read by the WASPLab and were adjusted manually whenever necessary. For the SIRscan 2000 automatic, the antimicrobial disc diffusion susceptibility testing was performed according to the EUCAST guidelines. The gradient strip method was used to resolve discrepancies. Results: The overall categorical agreement between the compared methods reached 99.1% (797/804; 95% CI 98.2%e99.6%), 99.5% (1029/1034; 95% CI 98.9%e99.8%), and 98.8% (2798/2832; 95% CI 98.3%e99.1%) for P. aeruginosa, S. aureus and the Enterobacterales, respectively. Conclusions: WASPLab incorporating the BioRad expert system provides a fully automated solution for antimicrobial disc diffusion susceptibility testing with equal or better accuracy than other available phenotypic methods.

Recent Developments in Phenotypic and Molecular Diagnostic Methods for Antimicrobial Resistance Detection in Staphylococcus aureus: A Narrative Review

“…A VME occurs when the reference method reports resistance but the test method reports susceptibility. A major error (ME) is the opposite scenario; a mE occurs when one method reports intermediate resistance but the other reports either susceptibility or resistance [ 51 ].…”

“…One limitation of the study could be that the Copan should have been compared with more similar methods rather than with the VITEK 2 [ 39 ]. In the same group, the authors evaluated the performance of an earlier semiautomated version of the Copan, reaching a similar performance [ 51 ].…”

Performance of Fully Automated Antimicrobial Disk Diffusion Susceptibility Testing Using Copan WASP Colibri Coupled to the Radian In-Line Carousel and Expert System

“…The Colibri prepared the inocula of 10 strains within 21 min. Then, that inoculum (2 × 30 µl loop/spreader) was streaked by the WASP over the entire surface of round Mueller-Hinton E (MHE) agar plates (bioMérieux, Geneva, Switzerland) according to the AST streaking pattern defined by Copan, which was previously tested and validated in our previous report ( 7 ). The antibiotic disks are then dispensed by the Radian in-line carousel and the inoculated media are transferred by conveyors to the automated incubators ( Fig.…”

Mini Review: Clinical Routine Microbiology in the Era of Automation and Digital Health

“…For example, the Kiestra TLA combined with MALDI-TOF has been shown to shorten the incubation time required to identify microbial pathogens (Mutters et al, 2014). Unlike Kiestra TLA, WASPLab ™ offers an automated solution for antimicrobial disc diffusion susceptibility testing with equal or better accuracy than other available phenotypic methods (Cherkaoui et al, 2020b).…”