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Chapter 1
formation of two strains commonly associated with biofilm formation
Pseudomonas aeruginosa and Staphylococcus aureus [117].
The methods applied by Buckingham-Meyer et al. varied quite significantly
in relation to fluid shear and operation system (batch or continuous flow
system). The CDC reactor (as previously described) and the drip flow
reactor biofilm (coupons into reactor vessel with flow on inoculated
medium passing through the reactor system) were used [117]. Other
methods included a dehydrated biofilm system (coupons taken out of CDC
reactor and dried in accordance to ASTM standards) and the dried surface
method (heavy inoculum of test organism allowed dry onto the surface for
2 hours in accordance to the ASTM standards). There was a significant
difference in density of biofilm formed on the surfaces and the reduction of
viable cells after treatment with disinfectant agents, which is discussed
further in chapters 2 and 4 of this thesis. The results suggested that
incorporating a number of variables into a reactor model, such as a high
shear environment, with continuous flow and mixing of nutrients may be
essential for testing the efficacy of disinfectants against a biofilm, that may
represent the most rigorous assessment of disinfectant activity against
biofilm [117].
Differences between biofilm grown in different reactors have also been
published elsewhere. Nailis et al. compared the phenotypic differences
between Candida albicans biofilm when grown in the biofilm surface
models (CDC biofilm reactor, microtitre based model) and biofilm animal
models (subcutaneous rat model and reconstructed human epithelial
model) [121]. Not only were there differences between the surface models
and the biofilm animal models, but there were major differences between
the CDC and the microtitre based model despite both growing the biofilm
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