Macroscopical and Microscopical Changes of Body Organs after E. coli O157:H7 Inoculation in Puppies

Abstract

E. coli O157:H7 are an important pathogen of human and animals. The puppies were divided into two groups randomly, infected group: (15 puppies) were drenched once orally with 5 ml bacterial suspension of PBS containing 5×107 CFU, and control group: (5 puppies) drenched 5 ml PBS, then specimens from internal organs including: kidney, intestine, liver, spleen, brain and lung after sacrificed puppies at (24hrs, 48hrs, 72hrs, 6 days, 12days, 24days, and 36days) from infected and control groups were used for histopathological examination. After inoculation, all animals were examined for presence or absence of signs. The shedding patterns of E. coli O157:H7 in feces were started after 24hrs. after inoculation and ceased at day 14th.The results of gross lesions of internal organs revealed no gross lesions in the intestine, kidney, lung and spleen at 24, 48 and 72 hours. While at days 6, 12, 24, 36 the intestine showed congestion and hemorrhage. Also the kidneys were swollen and showed congestion. The lung showed sever hemorrhages at day 12 post infection, also the spleen showed enlargement at day 24 post infection. The results of histopathological changes showed that E. coli O157:H7 infection caused thrombus development, necrosis, vacuolar degeneration of epithelial lining cells and congestion of blood vessels of kidney and intestine with superficial sloughing of epithelial mucosa of intestine at 24hrs and 48hrs. post-infection at 48hrs post-infection. Also the result revealed infiltration of inflammatory cells, vacuolar degeneration appeared in the examined organs at 72hrs. At 6-day post infection the infiltration of inflammatory cells became more prominent with severe congestion of blood vessels in examined organs. At day 12 post infection, there was mucus attachment in the epithelium of intestine, congestion of blood vessels, necrosis, with infiltration of the inflammatory cells in the examined organs. The most important event at day 24 post infection is the presence of regeneration in the intestine which became more prominent at day 36 post infection. This study aimed to highlighting the gross and histopathological effect of E. coli O157:H7 in different organs post inoculation in puppies. In conclusion, the shiga toxin can cause damage in many body organs like liver, spleen, kidney, lung, brain and intestine.