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●● The Normalized version of each algorithm (Norm) is com-
puted in the same way as the respective algorithm but the
value of the first image is subtracted from the subsequent
ones to build the growth/growth inhibition curve.
●● Once the algorithms for image analysis have been chosen,
press “Start” to start the time-lapse AST experiment.- Real-time growth/growth inhibition curves (“Growth Kinetics
Analysis”) and image data (“Acquire”) can be monitored dur-
ing the AST experiment in the “Current scan” tab. Notes
about the experiment can be added in the “Job overview” tab,
whereas the “Saved images” tab shows all the images that have
already been acquired for each scan area as either images or
time-lapse videos. In the same tab, curves for different scan
areas can be compared by (a) selecting “All items” from the
“Select scan area” drop down list and (b) ticking the scan areas
of interest in the list to the right of the displayed graph. Each
curve can be inspected in combination with the corresponding
time-lapse video by ticking the box “Show video.” - Export growth/growth inhibition curves and image data.
Press the “Export” button and select “Export chart,” “Export
image,” or “Export video” to export graphs as PNG files,
images as BMP files and time-lapse videos in the AVI format.
To export growth/growth inhibition values as Excel files or in
the CSV format, press the “Export” button and select “Export
to Excel” or “Export to CSV,” respectively.
4 Notes
- When analyzing samples with few and/or small bacteria, it may
be beneficial to add polystyrene beads of an appropriate size
(e.g., 3K/4K series particle counter standards, Thermo
Scientific) to facilitate the focusing process [ 19 ]. During the
analysis, the segmentation algorithm will be able to ignore the
beads. - The full list of compatible plate formats is reported in the
oCelloScope user manual. The oCelloScope is also compatible
with microscope slides using the specific slide holder. - When preparing multiple samples in a microtiter plate, it is
recommended to add the same volume to each well. This
allows the same settings for illumination and focus to be
applied to all wells. - The recommended total volume of bacterial suspension and
antibiotic solution to use is 50–200 μL. Smaller volumes can
Chiara Canali et al.