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Chapter 4
hours instead of the standardised 48 hour biofilm in order to investigate
the impact of time on bacterial resistance to disinfectant treatment. As
demonstrated in this research, it is also important to consider biofilm
development over an extended period of time.
The work presented in this chapter indicates that sodium hydroxide was
effective at eradicating a standard 48 hour Salmonella biofilm however; the
same concentration of sodium hydroxide was not effective at eradicating
all viable cells. This finding also highlights the importance of examining the
efficacy of disinfectant agents against a biofilm formed over an extensive
period of time.
Although sodium hypochlorite and benzalkonium chloride resulted in a
reduction of viable cells directly after exposure neither of the disinfectants
was effective at eliminating all viable cells from the 48 hour or 168 hour
biofilm. Moreover, the cells continued to grow after contact with the two
disinfectants for up to 90 minutes. As a results studies should also
investigate if any remaining cells may be able to recover and grow after
treatment. This emphasizes the need for complete elimination of all viable
cells from surfaces as opposed to a 4 or 5 log 10 reduction as it is otherwise
possible for cells to continue to grow on the surfaces.
All of these findings may be of critical significance to the food industry, as
the results demonstrate the importance of preventing Salmonella from
becoming established on a food producing campus, as once established in
a biofilm, Salmonella may be extremely difficult to eradicate.
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