RESUMEN
BACKGROUND: Sepsis is a life-threatening condition that impacts 49 million people annually and causes 11 million deaths worldwide. Surviving bloodstream infections (BSIs) depends on the rapid administration of effective antimicrobial treatment, underscoring a need for rapid antimicrobial susceptibility testing (AST). AIM: To evaluate the performance of Quantamatrix's dRAST v2.5 system (Seoul South Korea) for AST directly from positive blood cultures as compared to the Disk-Diffusion (DD) and VITEK 2 methods. METHODS: The study included 191 positive blood cultures from clinical samples and spiked blood culture bottles. Following Gram staining and species-level identification, AST was performed by VITEK 2 and standard DD methods using CLSI (2021) interpretation. RESULTS: dRAST demonstrated very good AST performance for a Gram-negative isolate, and good performance for Gram-positive isolates, meeting CLSI criteria for the acceptance of a new method. Antimicrobials that were not considered verified compared to VITEK 2 and DD were cefazolin, ceftazidime, meropenem, and trimethoprim/sulfamethoxazole for Gram-negatives and clindamycin, erythromycin, penicillin, and oxacillin for Gram-positives. dRAST ESBL detection results were strongly correlated with the ESBL phenotypes obtained with other methods. Additional resistance mechanisms were in concordance with traditional tests. CONCLUSIONS: dRAST demonstrated good AST performance, meeting CLSI criteria for most relevant antibiotics. dRAST was associated with a significant reduction in time-to-results, labor, and the subjectivity of result analyses, making it a valuable addition to efforts supporting the treatment of patients with bacteremia. AST (antimicrobial susceptibility test), blood culture, dRAST, rapid methods, sepsis, turnaround time (TAT).
RESUMEN
The disc diffusion test is used for antimicrobial susceptibility testing worldwide. In this study, the performance of both Bio-Rad® antibiotic discs (as compared with Oxoid® discs) and the ADAGIO™ automated system for the reading of disc diffusion test results was evaluated with American Type Culture Collection (ATCC) quality control (QC) and wild strains of bacteria. Inhibition zones of both disc brands were read manually and through use of the ADAGIO™ system. Categorized interpretation of the results for each strain and antibiotic combination was summarized according to the Clinical Laboratory Standards Institute MS-100 (2017 update) manual and ADAGIO™ readings. Eight ATCC QC strains and 120 different wild strains were evaluated, to give a total of 1226 antibiotic/bacteria combinations and 2486 manual readings. One major error and four minor errors (0.08% and 0.34%, respectively) were detected via manual readings of the Bio-Rad® discs as compared with the Oxoid® discs. For the same number of antibiotic/bacteria combinations, five minor errors and one major error (0.42% and 0.08%, respectively) were detected with the Bio-Rad® discs read by the ADAGIO™ system. In addition, the number of times the automatic reading needed manual edition with Bio-Rad® discs was statistically lower than it did with Oxoid® discs (3.7% vs. 5.7%, p < 0.05). These findings support the hypothesis that Bio-Rad discs are not inferior to Oxoid® discs, and the performance of the ADAGIO™ system is comparable to that of manual readings with both disc brands.
