Scientists at the University of Liverpool have demonstrated how Salmonella’s ability to survive in amoeba is a huge advantage to its continued development as it may be more resistant to disinfectants and water treatment.
Salmonella are known to thrive in damp environments; in the recent salmonella peanut butter recall scare in the US, the Food and Drug Administration (FDA) found mould on the walls and ceiling as well as a leaky roof in the plant of the food manufacturer involved, the Peanut Corporation of America (PCA).
The Liverpool researchers said their findings, which were published in the journal Applied and Environmental Microbiology show for the first time how Salmonella survives so successfully in the environment through the use of a secretion system to protect themselves inside amoeba, a single-celled organism living on land and in the water.
Dr Paul Wigley, from the National Centre for Zoonosis Research at the University, said that the pathogen has managed to survive extremely successfully in the environment, finding its way into food and causing illness, despite the body's best efforts to fight it off.
He said that the next stage of the research is to find new ways of controlling amoeba in water supplied to animals to prevent it acting as a 'Trojan Horse' for Salmonella and other pathogens.
According to Wigley, Salmonella uses a system, called SP12 type III, which acts as a bacterial machine inside organisms and causes disease in humans, animals and plants.
He explained that the system employs a 'syringe-like' mechanism to inject bacteria into cells that would normally release compounds to rid the body of harmful substances, and that this system changes the structure of the cell and prevents these compounds from coming into contact with
“We found that it uses a system which operates in the human immune system as well as inside amoeba living in the environment. This system essentially protects Salmonella within cellular compartments, called phagosomes, where it can survive and multiply.”
Source: Applied and Environmental Microbiology
Published online ahead of print
The Salmonella Pathogenicity Island 2-Encoded Type III Secretion System Is Essential for the Survival of Salmonella enterica Serovar Typhimurium in Free-Living Amoebae
Authors: B Bleasdale, P J. Lott, A Jaganathan, M P Stevens, R J. Birtles, P Wigley.