miércoles, 29 de enero de 2014

Salmonella Biofilms Extremely Resistant to Disinfectants

Disinfectants are not able to kill after 7 days growth of Salmonella 

Researchers at the National University of Ireland, Galway, have discovered that common disinfectants face an uphill battle killing Salmonella once it has had the time to form a biofilm – a community of cells that attach to each other and a surface, increasing the density of bacterial growth and providing support from harsh environments. Allowed Salmonella enterica cells to grow for seven days before applying three types of disinfectant:  sodium hypochlorite, sodium hydroxide and benzalkonium chloride.
They found that none of the disinfectants was able to kill the cells after that amount of time. Even soaking the biofilms in disinfectant for an hour and a half failed to kill them.
Once Salmonella cells are allowed to become established on a surface, the number of cells will increase over time, resulting in difficulty  if not impossible  to completely eliminate or kill all cells once part of a mature biofilm.
The strains she tested were able to form a biofilm on glass, steel, polycarbonate plastic, glazed tile and concrete.
In terms of ‘real world’ environments, it is estimated that most organisms are capable of this, and that a high percentage of micro-organisms will form a biofilm to optimize growth and survival.
To head off an issue of resistance,  recommended appropriate and frequent cleaning to prevent the buildup of bacteria on surfaces and improving handling practices such as ensuring raw food is prepared in a separate area from cooked food to reduce the risk of cross-contamination.


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