Salmonella forms biofilm that increases resistance to disinfectants

A research study has shown that Salmonella forming biofilms increases the organisms ability to withstand disinfectants, especially as the biofilm ages. This study showed that 168 hour old biofilm increased the probability of survival against disinfectants compared to 48 hour old biofilms. They suggest that these biofilms can help Salmonella survive in facilities for long periods of time

Salmonella can be very difficult to remove from an establishment once it has become established. One study showed that a Salmonella strain survived for 10 years in a facility despite intensive cleaning and decommissioning of contaminated equipment. Two recent outbreaks in the US ultimately resulted in the shuttering of operations after those facilities were not able to eliminate Salmonella from the environment.

Biofilms may only be part of the answer. Aged bacterial cells may have increased resistance. We know that Salmonella has survived in products like peanut butter for months. We know that in dry products, Salmonella has increased heat resistance. For example, almonds roasted in oil require a process of 1.6 minutes at a temperature of 260ºF to achieve a 4 log kill.
Food processors beware: Salmonella biofilms incredibly resistant to powerful disinfectants

Phys.org.com 1/15/14
http://phys.org/news/2014-01-food-processors-beware-salmonella-biofilms.html#jCp

Once Salmonella bacteria get into a food processing facility and have an opportunity to form a biofilm on surfaces, it is likely to be extraordinarily difficult, if not impossible, to kill it, according to research published ahead of print in the journal Applied and Environmental Microbiology.

Researchers from National University of Ireland, Galway conducted a study in which they attempted to kill Salmonella biofilms on a variety of hard surfaces, using three types of disinfectant.

"We found that it was not possible to kill the Salmonella cells using any of the three disinfectants, if the biofilm was allowed to grow for seven days before the disinfectant was applied," says Mary Corcoran, a researcher on the study. Even soaking the biofilms in disinfectant for an hour and a half failed to kill them