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Clinicians and Pathologists
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Clinicians and Pathologists
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Isolation of E. coli from Multiple Sites in Broilers Condemned for Cellulitis Brenda Allan Veterinary Infectious Disease Organization
Cellulitis is an important disease of broilers, resulting in significant losses to the industry due to condemnations at the time of slaughter. Cellulitis is characterized by an inflammation of the tissue under the skin. E. coli is commonly isolated from these lesions. An association between the occurrence of cellulitis and serositis has been reported. This study was undertaken to examine the relationship between E. coli isolated from cellulitis lesions and other lesions caused by E. coli in individual birds to determine if the bacteria present in all lesions were the same type. Birds condemned for cellulitis were obtained and examined for additional lesions. The cellulitis lesion, pericardium, liver, air sacs, lungs, and joints were cultured for bacteria using MacConkey agar and blood agar plates. Bacteria that were lactose positive (brick red in colour) when grown on MacConkey Agar were tentatively identified as E. coli. The identification of the E. coli isolates was confirmed using the BBL Crystal rapid identification system. In the summer of 1995, fourteen flocks were sampled and 127 birds with cellulitis examined. E. coli was isolated from all, but two of the cellulitis lesions cultured. Other lesions observed in birds that had been condemned for cellulitis included pericarditis, air sacculitis, osteomyelitis, polyserositis, hepatitis and arthritis. Forty two birds in all were observed to have at least one lesion in addition to cellulitis. From 26 of these birds we were able to culture E. coli from more than one additional site. Dual isolation of E. coli occurred in 7 of the 14 flocks sampled. Pairs of E. coli isolated from individual birds were serotyped at the E. coli Reference Center, Penn State University, for O and H antigens. Serogroups O78, O1 and O2 appeared to predominate in E. coli isolated from the cellulitis lesion and accounted for 57% of the cultures examined. Individual isolates of serogroups O15, O53, O56, O158, O115, and O152 were observed and five isolated were not typeable. When the O serogroup of the second E. coli isolated was compared to that of the E. coli isolated from the cellulitis lesion it was observed that 48% of the pairs were of the same serogroup and 48% of the pairs belonged to different serogroups. It was impossible to determine if one pair was the same of different as both isolates were not typeable. In conclusion, it appears that E. coli can be isolated from multiple sites in some birds condemned for cellulitis. The sites of isolation included the pericardium, air sacs, joints, liver, and lungs. The frequency of this dual isolation varied from flock to flock. In approximately half of the dual isolation, the pair of E. coli was of the same serogroup and is potentially the same bacterium. E. coli of serogroups O1, O2, and O78 were commonly isolated. It appears that E. coli of a single serogroup is capable of causing more than one type of lesion in an individual bird. Based on these data it is impossible to tell the relationship between the development of the lesions. It is tempting to speculate that E. coli escaped from the cellulitis lesion and was carried throughout the body. However, it is also possible that the lesion arose independently and was caused by a particularly virulent strain of E. coli present in the flock. |
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