Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Diagnosing clostridial enteric disease in poultry

The world’s poultry industry has grown into a multibillion-dollar business, the success of which hinges on healthy intestinal tracts, which result in effective feed conversion. Enteric disease in poultry can have devastating economic effects on producers, due to high mortality rates and poor feed efficiency. Clostridia are considered to be among the most important agents of enteric disease in poultry. Diagnosis of enteric diseases produced by clostridia is usually challenging, mainly because many clostridial species can be normal inhabitants of the gut, making it difficult to determine their role in virulence. The most common clostridial enteric disease in poultry is necrotic enteritis, caused by Clostridium perfringens, which typically occurs in broiler chickens but has also been diagnosed in various avian species including turkeys, waterfowl, and ostriches. Diagnosis is based on clinical and pathological findings. Negative culture and toxin detection results may be used to rule out this disease, but isolation of C. perfringens and/or detection of its alpha toxin are of little value to confirm the disease because both are often found in the intestine of healthy birds. Ulcerative enteritis, caused by Clostridium colinum, is the other major clostridial enteric disease of poultry. Diagnosis of ulcerative enteritis is by documentation of typical pathological findings, coupled with isolation of C. colinum from the intestine of affected birds. Other clostridial enteric diseases include infections produced by Clostridium difficile, Clostridium fallax, and Clostridium baratii.

Quantification of cell proliferation and alpha-toxin gene expression of Clostridium perfringens in the development of necrotic enteritis in broiler chickens

Cell proliferation and alpha-toxin gene expression of Clostridium perfringens in relation to the development of necrotic enteritis (NE) were investigated. Unlike bacitracin-treated chickens, non-bacitracin-treated birds exhibited typical NE symptoms and reduced growth performance. They also demonstrated increased C. perfringens proliferation and alpha-toxin gene expression that were positively correlated and progressed according to the regression model y = b(0) + b(1)X - b(2)X(2). The average C. perfringens count of 5 log(10) CFU/g in the ileal digesta appears to be a threshold for developing NE with a lesion score of 2.

Highly conserved alpha-toxin sequences of avian isolates of Clostridium perfringens

Clostridium perfringens causes necrotic enteritis in chickens, and alpha-toxin has been suggested to be a key virulence determinant. Analysis of the alpha-toxin of 25 chicken-derived C. perfringens strains demonstrated high homology to mammal-derived strains rather than to the only avian-derived C. perfringens alpha-toxin sequence reported previously.

Clostridial population and the intestinal lesions in chickens infected with Clostridium perfringens and Eimeria necatrix

Chickens infected with Clostridium perfringens and Eimeria necatrix were examined bacteriologically and pathologically. When chickens were inoculated with 1.0 x 10(8) C. perfringens and/or 2 x 10(4) E. necatrix sporulated oocysts, populations of C. perfringens in the intestinal contents were examined on 3, 5 and 7 days after E. necatrix inoculation. In both groups infected with E. necatrix, the mean clostridial counts were significantly higher than those of uninfected controls. The concurrent infection had no enhancing effects on increasing the clostridial population more than E. necatrix-alone. Mortality of 4-day-old chickens inoculated on 5 consecutive days with C.perfringens after receiving E. necatrix was higher than those of chickens inoculated with the both organisms. However, intestinal lesions of the concurrently infected group were not different from E. necatrix-alone-infected group on 5 and 7 days after the coccidial infection. When chickens received a large dose (1.5 x 10(9)) of C. perfringens after the inoculation with E. necatrix, edema in the duodenum through jejunum were observed early after the bacterial broth inoculation. These results suggest that the concurrent infection with E. necatrix and C. perfringens increases clostridial population in the intestine of the chickens and has synergic effects on mortality and edema in the upper intestine.

In vitro and in vivo evaluations of the antibiotic efrotomycin

Experiments were conducted to determine the potential of the antibiotic efrotomycin as a growth permittant for poultry and to further elucidate the mode of action of antimicrobial agents for that purpose. Efrotomycin as the semipurified antibiotic and as fermentation solids demonstrated excellent activity against Clostridium perfringens at .1 to .2 ppm based on suppression of gas production in an anaerobic tube test. Supplementing a soybean protein and sucrose-based diet with levels of 2.2, 11, and 55 ppm of the antibiotic, from the two sources each with two different purities, improved weight gain of chicks an average of 23% and improved feed efficiency an average of 13% at the higher levels (all P less than .01). Computed indexes for each antibiotic treatment, which represent the combined effects of both weight gain and feed efficiency, showed that a maximum response was generally obtained at the 11 ppm level and that the antibiotic as fermentation solids was slightly more active than the semipurified material. Supplementing the soybean protein and sucrose-based diet with levels of 1.1, 5.5, 16.5, and 55 ppm of efrotomycin reduced the numbers of C. perfringens organisms in ileal contents of chicks (all P less than .01). The effects were dose-related. Control chicks in this experiment averaged greater than 7.7 log10 of C. perfringens counts per gram of contents. The results of these experiments show that efrotomycin has excellent growth-permittant activity and the activity correlates with the antibacterial activity against C. perfringens.