ISOLATION AND PATHOLOGICAL INVESTIGATION OF COLIBACILLOSIS IN BROILER AT SYLHET DISTRICT 2014

Abstract

The aim of the present study was to determine the isolation of causal organisms and pathology of colibacillosis in broilers at Sylhet district of Bangladesh during the period from December 2013 to May 2014. For this purpose, a total of 122 swab samples were collected from 74 healthy and 48 sick and dead broilers during the period from December 2013 to May 2014. Cloacal swabs were collected only from apparently healthy birds and visceral swabs were collected only from sick and dead birds. After collection, samples were subjected to bacterial isolation and identification. The isolation and identification of bacteria were performed by culturing in different media, staining and biochemical tests. The histopathological samples from dead birds were collected in 10% neutral buffered formalin. The collected tissues were fixed, processed, sectioned, stained and studied under light microscope. E. coli was isolated from 81.08% of cloacal swabs of apparently healthy birds and 85.42% from sick and dead birds. The overall isolation was 82.79% in healthy, sick and dead broiler. The organism produced yellow green metallic sheen in EMB agar and pink color colony on MacConkey agar. On gram staining, organisms were found gram negative, pink color, rod shaped organism. On biochemical tests, organisms fermented five basic sugars (dextrose, lactose, sucrose, maltose and mannitol) with production of acid and gas and these were found Indole test, MR test and Catalase test positive but VP test negative. Grossly there were cloudy and thickened air sacs, fibrinous perihepatitis, pericarditis, congestion and consolidation in the liver, lung and spleen in some broilers. Congestion and hemorrhages in the duodenum and excess mucus in the duodenum was also observed. There were also petechial hemorrhages in spleen, heart and liver. Microscopically there were infiltration of heterophils, lymphocytes and macrophages in liver and lung. Thickening of pericardium of the heart was found due to infiltration of RE cells. In spleen there was scattered pyknosis of lymphocyte. E coli infected all the duodenum showed severe infiltration of leukocytes mainly heterophils, lymphocytes and macrophages in the sub mucosa of the duodenal wall.