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Pathological Investigation And Molecular Detection Of Avian Pathogenic E.Coli Serogroups In Broiler Birds

By: Muhammad Azeem Riaz (2008-VA-132) | Prof. Dr. Asim Aslam.
Contributor(s): Dr. Muti Ur Rehman Khan | Prof. Dr. Tahir Yaqub.
Material type: materialTypeLabelBookPublisher: 2016Description: 50p.Subject(s): PathologyDDC classification: 2591-T Dissertation note: The present study was designed to identify the serogroups present in field and to study their pathological effects in experimentally infected broiler chicks. The present study was attempted to scan the rfb gene clusters in APEC predominant serotypes O1, O2 and O78 strains and to develop Multiplex PCR method for serotyping of the O-antigens. The Multiplex PCR method was used for the identification of serotypes of APEC. The second part of the study was to study the pathological lesions caused by most prevalent serogroup in experimentally infected broiler chicks. A total of 100 tissue samples (lungs and livers) were collected from colibacillosis suspected broiler birds. Streaking was done from these samples on three different media and it was found that 80% isolates were positive on MacConkey media, 60% were positive on EMB media and 40% were found pathogenic for E.coli on Congo red media. The colonies which were of pink color on congo red media were considered as pathogenic. DNA was extracted from these colonies by boiling method by picking single colony from each petri plate. Extracted DNA was further used for PCR to confirm the three serogroups i.e O1, O2 and O78. The PCR results showed that 8% isolated samples were found as pathogenic as O2 strain was found dominant among all. Only two genomic DNA samples were found of O1 serogroup After confirmation of serogroups inoculum of Avian pathogenic E.coli O2 strain was prepared to experimentally infect the broiler birds. Birds were infected at the age of day 7 via intratracheal route. Following the experimental infection of birds, they were monitored for any pathological lesions which were not present significantly while some birds were off feed, reluctant to move, head down posture and were keeping themselves in isolation. Summary 46 Postmortem of dead birds was performed and pathological lesions were noted. Livers were found to be congested, enlarged and white fibrinous layer over liver was present. Lungs were also affected with the disease and white layer was present on lungs too. Lungs were consolidated and congested. Histopathology of lungs and livers was performed. It was noted that there was mononuclear cells infiltration and thin fibrinous layer over liver. Thickening of the liver capsule was noted due to infiltration of mononuclear cells and there was marked congestion in hepatic portal areas and the central vein. There was atrophy of adjoining hepatic cords due to greatly distended and congested sinusoids. Besides these changes, hepatocytes in various stages of degeneration along with hemorrhages, areas of congestion and fatty changes in a few places could be seen. There was infiltration of heterophils, severe congestion, lymphocytes and macrophages in the wall of the bronchus as well as in the peribronchial alveoli. There was marked presence of granuloma in lungs. Some birds displayed thickening of the pleura and consolidated areas covered with yellowish fibrin in lungs. The experimental infection of avian pathogenic E.coli confirmed the hypothesis that it causes pronounced histopathological lesions in broiler birds.
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The present study was designed to identify the serogroups present in field and to study their pathological effects in experimentally infected broiler chicks. The present study was attempted to scan the rfb gene clusters in APEC predominant serotypes O1, O2 and O78 strains and to develop Multiplex PCR method for serotyping of the O-antigens. The Multiplex PCR method was used for the identification of serotypes of APEC. The second part of the study was to study the pathological lesions caused by most prevalent serogroup in experimentally infected broiler chicks.
A total of 100 tissue samples (lungs and livers) were collected from colibacillosis suspected broiler birds. Streaking was done from these samples on three different media and it was found that 80% isolates were positive on MacConkey media, 60% were positive on EMB media and 40% were found pathogenic for E.coli on Congo red media.
The colonies which were of pink color on congo red media were considered as pathogenic. DNA was extracted from these colonies by boiling method by picking single colony from each petri plate. Extracted DNA was further used for PCR to confirm the three serogroups i.e O1, O2 and O78.
The PCR results showed that 8% isolated samples were found as pathogenic as O2 strain was found dominant among all. Only two genomic DNA samples were found of O1 serogroup After confirmation of serogroups inoculum of Avian pathogenic E.coli O2 strain was prepared to experimentally infect the broiler birds. Birds were infected at the age of day 7 via intratracheal route.
Following the experimental infection of birds, they were monitored for any pathological lesions which were not present significantly while some birds were off feed, reluctant to move, head down posture and were keeping themselves in isolation.
Summary
46
Postmortem of dead birds was performed and pathological lesions were noted. Livers were found to be congested, enlarged and white fibrinous layer over liver was present. Lungs were also affected with the disease and white layer was present on lungs too. Lungs were consolidated and congested.
Histopathology of lungs and livers was performed. It was noted that there was mononuclear cells infiltration and thin fibrinous layer over liver. Thickening of the liver capsule was noted due to infiltration of mononuclear cells and there was marked congestion in hepatic portal areas and the central vein. There was atrophy of adjoining hepatic cords due to greatly distended and congested sinusoids. Besides these changes, hepatocytes in various stages of degeneration along with hemorrhages, areas of congestion and fatty changes in a few places could be seen.
There was infiltration of heterophils, severe congestion, lymphocytes and macrophages in the wall of the bronchus as well as in the peribronchial alveoli. There was marked presence of granuloma in lungs. Some birds displayed thickening of the pleura and consolidated areas covered with yellowish fibrin in lungs.
The experimental infection of avian pathogenic E.coli confirmed the hypothesis that it causes pronounced histopathological lesions in broiler birds.

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