M.M. Klerks: “Human pathogenic Salmonella in association with lettuce”

Salmonella closely associated with lettuce

Salmonella is one of the most commonly known bacterial pathogens to cause human illness. During the last decades there has been an increase of outbreaks caused by human pathogenic bacteria originating from fresh produce. The use of manure for production of vegetables, e.g. lettuce, contributes significantly to the risk of contamination of fresh produce.
This research has focused on the development of methods for quantitative detection of Salmonella enterica and Escherichia coli O157:H7 with high sensitivity, accuracy and precision, applicable in routine screening in the food production chain. Using these methods the test time of food products can be reduced to two days compared to five days required for the standard procedures.
The physiological and molecular interactions between Salmonella serovars and lettuce cultivars were also investigated. Salmonella was able to actively move towards lettuce roots and colonize the plant. A plant defense mechanism was activated upon colonization, but no physiological differences were observed between healthy and contaminated lettuce plants grown on soil. Salmonella was able to colonize lettuce both epiphytically (on the plant) and endophytically (in the plant). Endophytic contamination may increase the risk of human illness, especially when contaminated lettuce is cut and bagged for fresh consumption.

Title thesis: "Quantitative detection of salmonella enterica and the specific interaction wsith Lactuca sativa"