Assessment of bacteriological contaminants of some vegetables irrigated with Awash River water in selected farms around Adama town, Ethiopia

Food safety issues are of growing concern to consumers globally because of the risk associated with consumption of foods contaminated with pathogens in irrigated vegetables. The study was conducted to assess the extent of bacterial contamination of vegetables due to irrigation with polluted Awash River water. Three leafy vegetable samples, namely, cabbage (Brassica oleracea L. var. capitata), lettuce (Lactuca sativa L. longifolia) and spinach (Spinacea oleracea) from both farms were examined for bacterial contaminants. The results show that spinach was found to be the most heavily contaminated vegetable in both farms by aerobic bacteria. The aerobic mesophilic bacterial count on this vegetable was 2.2×108 and 2.0×108 CFU/g, for spinach sampled from Melka Hida and Wonji Gefersa vegetable farms, respectively. The highest total coliform count (6.6×106) was also recorded from lettuce in Melka Hida vegetable farm. The mean fecal coliform values of all the three vegetable samples exceed the International Commission on Microbiological Specifications for Foods (ICMSF) recommended level. The highest faecal coliform count (5.7×105) was recorded in cabbage sampled from Wonji Gefersa. The high microbial contamination rates associated with these vegetable samples indicated poor water quality for irrigation employed in the overall production of vegetables in the study area.    Key words: Indicator bacteria, pathogen, vegetables.