PATHOLOGICALSTUDY ON COLIBACILLOSIS IN CHICKENS AND DETECTION OF ESCHERICHIA COLI BY PCR
The aim of the present study was to detect the pathogenic Escherichia coli (E. coli) through pathological study of the colibacillosis affected birds. These isolated E. coli were further confirmed by PCR using specific primer. For this purpose, a total of 20 swabs (10 from lung and 10 from intestine of 10 dead birds) were collected in sterile nutrient broth. The histopathological samples were collected in 10% buffered neutral formalin. The used methods were histopathology, isolation and identification of E. coli by conventional methods and as well as by PCR method. A total of 10 isolates of E. coli from 20 swabs of lung and intestine was characterized by conventional routine methods of bacteriology. Gross pathological lesions of all lungs in the present investigation were congested and consolidated. Duodenum showed congestion and hemorrhages with excess mucus in the luminal surface of it. Microscopically, all the lungs showed severe congestion, infiltration of heterophils, macrophages and lymphocytes in the wall of bronchus as well as in the peribronchial alveoli. E. coli infected all the duodenum showed severe infiltration of leukocytes mainly heterophils, lymphocytes and macrophages in the submucosa of the duodenal wall. In this study, DNA of 8 isolates out of 10 isolated E. coli organisms was amplified by PCR using ECO-f and ECO-r primer targeting 16S ribosomal DNA and found 585 bp amplicon which is specific for E. coli with enteroinvasive type confirmed by histopathological lesions in duodenum. Further investigation should be focused on serotyping and detection of genes of E. coli which are responsible for pathogenicity of the organism.
Bangl. J. Vet. Med. (2011). 9(1): 17-25