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Chapter 5
5.3.6. Examining the efficacy of disinfectant products against an
established biofilm using the microtitre plate based system
Sodium hypochlorite (500mg/L), sodium hydroxide (1M) and benzalkonium
chloride (0.02%) were not effective in eliminating all viable cells from the
surface of the microtiter plate after an established biofilm was formed for
48 hour or 168 hour biofilm at 22°C and 37°C. The results presented in
Table 5.8 summarises all conditions (2 temperatures and 2 durations).
Despite the use of contact times of 10-, 45- and 90-minutes with the
disinfectants, the turbidity of the sterile broth increased when incubated
for an additional 24 hours (both at 22°C and 37°C), indicating that the cells
associated with the biofilm remained viable and were capable of
withstanding disinfectant treatment.
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