A researcher in Galway has discovered that if Salmonella bacteria get into a food processing facility, they are extremely difficult to kill.

Salmonella infection is a common bacterial disease affecting the intestinal tract. The most common source of infection is via contaminated water or food. Infection can lead to abdominal cramps, fever and diarrhoea. While most people will recover, infection among vulnerable people such as the elderly, can be more dangerous.

NUI Galway researcher and microbiologist, Dr Mary Corcoran, attempted to kill Salmonella found on a number of hard surfaces. She used three different types of disinfectant.

She found that once the bacteria had established themselves for seven days, the three disinfectants could not kill them, even if the Salmonella were soaked in disinfectant for 90 minutes.

There are a number of different types of Salmonella bacteria, however Dr Corcoran found that all were able to adapt to the surface they were on, including glass, stainless steel and concrete.

In fact, the bacteria appeared to become more dense over time and more firmly attached to the surface.

"Food processing facilities must take strict care to keep Salmonella out of the clean areas where cooked foods get further processed and packaged, and ask whether disinfectants that are promoted as killing various types of bacteria are really as effective as claimed," Dr Corcoran said.

Her research was prompted by a Europe-wide Salmonella outbreak in 2012, which affected over 160 people in 10 different countries. It was eventually traced to meat that had come from a major food processing facility.

"It seems that the outbreak entered into the environment in the part of the facility where meat that was already cooked was being handled, and it had survived and contaminated the cooked meat," she explained.

The three disinfectants tested by Dr Corcoran included household bleach.

"The research shows that a lot of the time, the disinfectant may add very little, if anything, to good cleaning and appropriate food handling practices and that there is a need for more research to define better methods for killing Salmonella," she added.

Details of these findings are to be published in the Journal of Applied and Environmental Microbiology.