Isolation and characterization of Escherichia coli from broilers and layers
2000
Nizamani, Z.
Poultry carcasses from various poultry farms were collected and brought to the Department of Microbiology, Sindh Agriculture University, Tandojam and Central Veterinary Diagnostic Laboratory, Tandojam and were investigated through postmortem examination and lesions of typical appearance caused by E. coli were recorded. A total of 150 poultry carcasses. 75 broilers and 75 layers were collected and examined for the presence of gross necrotic lesions on various organs of the 75 broilers, 3 age groups were investigated. Group A with age of 1-4 weeks, group B and C were of 4 - 8 and 8 - 12 weeks of age respectively. From each group 25 poultry carcasses were investigated. The higher incidence of E. coli infection was recorded in group A followed by groups B and C respectively. On the other hand, 75 carcasses of layers were studied through postmortem examination. Of the 25 carcasses with age of 1-8 weeks from group A, where as the birds of 8-16 and 16-24 weeks of age from group B and C respectively. During this study, a higher infection rate recorded in birds of 1-8 weeks compare to letter two groups. Five deferent organs, livers, intestines. lungs, hearts and ovaries of broilers each of 25 in number from 3 age groups collected and examined. The highest positive percentage for E. coli was recorded in intestine (80%) followed by liver (68%), heart (64%), lungs (56%) and ovary (32%) in age group of I - 4 weeks as compared to other two groups. From layers same type and number of organs were examined. The highest infection rate was recorded in intestine (84%) followed by liver (72%), heart (68þ%), lungs (60%) and ovary (30%) in age group of I-8 weeks as compared to group B and C. Morphologically, E. coli were coccobacilli shaped with 0.5 x 1 to 3 micron in size and found singly, and occasionally in pairs. They were gram-negative and motile. E. coli produced turbid growth in nutrient broth, and pinkish, small circular entire, smooth, translucent, and convex colonies on MacConkey's agar. On blood agar, colonies were non-hemolytic, grey white. moist, glistening, opaque, circular and convex with entire edge. Biochemical, E. coli was positive for urease, indole, catalase and methyl red but negative for urease, Simmon,s citrate, hydrogen sulphide, oxidase, Voges Proskauer and gelatin. E. coli also fermented different sugars and properties, such as acid and gas productions were noted. In this study antibiotic sensitivity of the identified organism was investigated. Eight different antibiotics were applied and sensitivity was observed. Gentamycin and kanamycin were observed highly effective against E. coli.
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