Figure 4
Automated eQUANT workflow and performance. The eQUANT method & instrument were used for automated eMcF generation from 23 positive blood cultures spiked with seven different species—E. coli (ECo), E. cloacae (ECl), K. pneumoniae (KPn), K. oxytoca (KOx), C. freundii (CFr), S. marcescens (SMa), and K. aerogenes (KAe). (A) Illustration of the eQUANT workflow. An aliquot of a PBC is diluted 1:30 in growth media, transferred into the eTube and inserted into the eQUANT instrument. The organism ID is selected from the menu, and the species-specific algorithm is used for eMcF generation. The resulting standardized inoculum is then used for inoculation of conventional AST (e.g. automated AST platforms, Kirby-Bauer Disk Diffusion). (B) Photo of the eTube consumable with integrated ORP sensor, unfilled with cap removed (left) and filled with a diluted positive blood culture sample (right). (C) The resulting eMcF samples were plated and colonies were counted to determine the bacterial concentration. The dotted lines represent the error ranges of the targeted 1.5 × 108 CFU/mL concentration for all species tested (± 0.2log, ± 0.3log, ± 0.4log). (D) Time to eMcF for all samples were recorded and ranged from 40 to 149 min with an average time of 106 ± 28 min. (e) Time to eMcF was plotted as a function of PBC colony counts for each species, and a Pearson Correlation was performed (dotted line). The resulting Pearson coefficient of -0.65 indicates a moderate negative correlation between time to eMcF and PBC starting concentration.
