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Chapter 5
5.5. Limitations of the study
The microtitre plate method has particular advantages such as it is more
suited to deal with large scale screening of isolates for biofilm capabilities
than other methods such as the CBR. It is also less time consuming and
more cost effective. Despite the notable advantages of high-throughput
analysis, there are certain limitations as briefly summarised here as
follows.
The range in repeated measure of OD 590 of stained biofilm for particular
strains was notably high. However, it would appear that other authors have
made comparisons of data with a similar variation in repeated measures,
with the use of standard error to indicate the amount of variation [56, 95].
Due to time constraints improving the repeatability through optimizing the
biofilm formation and measurement method was not examined more
closely. It was also not possible to read the optical density in a second plate
reader to assess if this extent of variation represented a problem with
performance of the plate reader used or an inherent issue with the method.
Previous authors have also used heat [159] or chemical fixation [165] in
order to increase reproducibility of reading optical density of biofilm
formed. However, this may result in an over estimation in the volume of
biofilm cells to the surface as it is likely that planktonic cells may also be
attached to the surface. It may have been of interest to investigate if the
use of acetic acid to resuspend the dye as this may have been more
effective than ethanol: acetone solution [111, 165].
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