Entero-hepatic pathobiology: histopathology and semi-quantitative bacteriology of the duodenum

Abstract

Duodenum swabs were harvested from 80 broilers in 15 flocks of 8 broiler farms and were submitted to bacteriological evaluation. Five broiler breeders were sampled to obtain comparative data. Macro and microscopic lesions in the gut and the liver were evaluated in all birds submitted to swab harvesting and also broilers of two slaughter plants. Semiquantitative bacterial examination in duodenum swabs demonstrated higher microorganism growth in blood agar than in MacConkey medium. Staphylococcus sp, Enterococcus sp and Escherichia coli were found in some broiler flocks. An increased cellularity of the muscular mucosae of duodenum villi and/or the presence of some gametocytes or schizonts of coccidia were found in the lesioned gut in addition to high bacterial growth in blood agar. In some flocks, enlarged yellowish livers with vacuolated hepatocytes and/or increased reticuloendothelial response were seen in some birds. Liver and gut samples were collected in two slaughter plants in order to establish a pattern of response in broilers after withdrawal of growth promoters. Livers with macroscopic lesions presented microscopic lesions in the parenchyma such as increased leukocyte response in the sinusoidal space, vacuolar degeneration of hepatocytes or focal necrosis in the perilobular region, increased size or number of lymphoid nests in the perilobular region, the perivascular space and surrounding the biliary duct and increased extramedular granulocytopoiesis. Duodenum with hyperemic patches showed increased cellular response in the muscular mucosa of villi. These observations support the concept that semi-quantitative bacteriology and liver lesion evaluation could be used as a model to study gut bacterial imbalance in chickens.