Evaluation of Salmonella and Listeria monocytogenes Contamination on Leafy Green Vegetables

Abstract

The objective of this study was to monitor Salmonella and Listeria monocytogenes contamination of leafy green vegetables produced in urban and periurban agricultural fields with natural water irrigation. A total of 164 samples comprising of different leafy green vegetables (8 basils, 15 dills, 20 garden cresses, 16 kales, 12 lettuces, 19 mints, 19 parsleys, 18 purslanes, 1 radish, 20 rockets, 14 scallions and 2 spinaches) were randomly collected from nearby agricultural fields in the close vicinity of Ankara Stream over an 8-month period between April 2007 and November 2007. Samples were examined for Salmonella and L. monocytogenes using ISO methods with immunomagnetic separation (IMS) and then polymerase chain reaction (PCR). No Salmonella and L. monocytogenes was detected from the 25-g radish, spinach and scallion samples tested. However, 23 samples (1 basil, 2 dills, 1 garden cress, 1 kale, 2 lettuces, 4 mints, 3 parsleys, 5 purslanes and 4 rockets) were positive for Salmonella and 14 samples (3 basils, 1 dill, 1 garden cress, 2 kales, 1 lettuce, 1 mint, 2 parsleys, 1 purslane and 2 rockets) were positive for L. monocytogenes. Overall, important contamination of leafy green vegetables by Salmonella and L. monocytogenes was observed. Therefore, this study will draw attention to the production of freshly consumed leafy green vegetables and so will aid in the development of control measures for these pathogens before harvesting and will highlight the importance of their intake which may cause a communicable disease and so pose a serious threat to both environment and human health.