In-vivo Effect of Probiotics on Escherichia coli O157:H7 Isolated from Salad Vegetables

This study was undertaken to isolate Escherichia coli O157:H7 from salad vegetables, determine its pathogenicity and effect on the gastrointestinal tract of mice and sensitivity to probiotics; Lactobacillus lactis ATCC12315 and Lactobacillus acidophilus ATCC4356 in-vivo. Twenty seven samples made up of eight different types of salad vegetables which includes carrot, cabbage, cucumber, lettuce, peas, green pepper, green beans and spring onions were collected from different locations; markets, farm and street vendors in Lagos, Nigeria. Sampling was done between 13th October 2009 and 17th March 2010. In all experiments with mice the protocol for care of animal was carried out according to National Institute of Health (NIH). The mice given only E. coli O157:H7 developed diarrhea which led to loss of body weight and death of majority of them. On the other hand mice that were not given any microbial suspension (control), those given only probiotics, combination of E. coli O157:H7 and probiotics showed no symptom of diarrhea and there was increase in their body weight. The histopathology of the intestines of this group of mice showed that their intestines were not damaged, while those given only E. coli O157:H7 showed lymphoid hyperplasia, mucosal sloughing and inflammation (enteritis). The maintenance of good health by probiotics has again been re-emphasized.