Western
Meeting of Poultry
Clinicians and Pathologists
|
Clinicians and Pathologists
|
|
Identification and Characterization of the Causative Agent of a New Type of Cellulitis in Turkeys Dr. Brenda AllanVeterinary Infectious Disease Organization
BackgroundOver the last 10 years, cellulitis has emerged as a major problem in the broiler industry and is consistently the largest single cause of condemnation due to infectious disease. Escherichia coli is usually the causative agent of cellulitis in broilers. Cellulitis lesions in turkeys have been associated with damaged skin and contact dermatitis. In the past, Clostridium perfringens and other Clostridium species have been identified as the causative agent of cellulitis in turkeys. Although both problems are referred to as cellulitis, they are two distinct syndromes.
In the past two years, observations of a new type of cellulitis lesions in turkeys have been made. This new lesion closely resembles that observed in broiler chickens. To date little information has been collected on the causative agent(s) of these lesions. At this time the new type of cellulitis lesion in turkeys is a relatively minor problem but, based on the experience with broilers where cellulitis has increased dramatically, it should not be ignored. Collection of information on this new syndrome will facilitate its control before it becomes a problem of the magnitude of cellulitis in the broiler industry.
Research Approach Birds that appeared to have cellulitis were identified at the time of slaughter (after the feathers were removed but before evisceration). The birds were examined to confirm the presence of the lesion and the size, location and physical characteristics of the lesions were recorded. Bacterial cultures were taken from the lesion and incubated on selective and nonselective media to detect aerobic, microaerophilic, and anaerobic bacteria. Lesions were also sampled and examined for histopathology. The birds were examined for other lesions. Samples for bacteriologic culture were taken from the air sacs, pericardium, and joints whether or not gross abnormalities had been identified. The bacteria were identified using appropriate biochemical tests.
Results and DiscussionEighteen flocks of turkeys from nine producers in Saskatchewan were examined in the fall of 1999. Only 37 of the over 25,000 birds examined were identified as having cellulitis lesions similar to those observed in broilers. The lesions occurred on the legs and caudal thoracic area. Some birds had lesions in more than one area. The lesions contained a dry to semi-dry exudate. Clearly the incidence of this type of lesion remains very low and no other lesions were observed in these birds.
On gross examination, lesions were grouped into two groups: (a) cellulitis with unopened skin lesions and (b) cellulitis with open skin lesions. Histopathologically, cellulitis with unopened skin lesions had dermal necrosis with underlying fibrin and inflammatory exudate. In contrast, cellulitis lesions with open skin had chronic granulomatous/granulation tissue type reaction associated with the presence of foreign material.
A complete bacteriologic study was conducted on 25 of the 37 birds. Aerobic bacteria were isolated from 12 of the 25 birds with cellulitis lesions. E. coli was isolated in low numbers from 9 of the 12 birds. E. coli was never isolated in pure culture. Other bacteria isolated with E. coli included Proteus mirabilis, Lactobacillus spp. Klebsiella spp. and Staphylococcus spp. The remaining three cases yielded P. mirabilis in pure culture or mixed with Pseudomonas aeruginosa. No aerobic, microaerophilic or anaerobic bacteria were isolated from the other 13 birds. Clostridium species were not isolated from any of the birds examined.
It appears that, while these lesions appear similar to those observed in broiler chickens, the situation is somewhat different. It is almost always possible to isolate E. coli from cellulitis lesions observed in broilers and it is often possible to isolate E. coli in pure culture. In contrast, we isolated E. coli in very low numbers from the turkeys and never in pure culture. While it is not possible to eliminate the possibility of infection contributing to the lesions, it appears that no single organism is responsible. It is possible that turkeys are able to clear the infection while the broilers are not able to do this by time of slaughter. ConclusionThe new syndrome observed in turkeys is similar in physical appearance to cellulitis in broilers. However, the underlying cause of the lesions seems to be different. The unopened skin lesions appeared to be due to contact dermatitis while the open skin lesions appeared to be due to a primary skin abrasion followed by contamination with foreign material.
|
|
To send us your comments or questions regarding this web site, click here. |