Microbiological Quality of Leafy Vegetables Irrigated with Wastewater in Harar Town Vegetable Farm, Eastern Ethiopia

摘要

Food safety issues are of growing concern to consumers globally because of the risks associated with consumption of foods contaminated with pathogenic microbes. Harar town vegetable farm is known to produce vegetables irrigated with wastewater. To what extent these vegetables are contaminated with pathogenic microbes was not known. The study was aimed to examine the extent of microbial contamination of vegetables. Thus, a laboratory based cross sectional study was conducted from October 2016 to January 2017. Accordingly, a total of 72 samples from four leafy vegetables namely lettuce (Lactuca sativa), spinach (Spinacea oleracea), kale (Brassica carinata) and cabbage (Brassica oleracea) were examined. The results revealed that the mean values in all vegetables were 9.5x10 7 CFU/g for total aerobic mesophilic bacterial count, 4.3x10 6 CFU/g for total coliform and 4.6x10 5 CFU/g for fecal coliform count. All the mean values exceeded the International Commission on Microbiological Specifications for Foods recommended levels for leafy vegetables. These leafy vegetables were also examined for some pathogenic bacteria (Salmonella, Shigella and Campylobacter species) and infective parasitic stages (Ascaris lumbricoides eggs, Entamoeba histolytica and Giardia lamblia cysts). Salmonella, Shigella and Campylobacter species were isolated in 12.5%, 9.7% and 2.8%, respectively, of all vegetables. Ascaris lumbricoides eggs was the predominant (43.5%) intestinal parasitic stage detected in the present study, followed by Entamoeba histolytica (25%) and Giardia lamblia cysts (15.3%). The findings of this study have important information on the implications of public health by transmission of pathogenic bacteria and infective parasitic stages among vegetable consumers of Harar town and the surroundings. Thus, it is recommended that the concerned public health authorities need to create awareness in the community and discouraging the use of untreated wastewater for cultivating vegetables.