Swine multifocal ulcerative colitis and crypt abscesses associated with Entamoeba polecki subtype 3 and Salmonella Typhimurium

Piglets aged approximately 50 days exhibited diarrhea and wasting. Multiple white foci were detected in the colon of a dead piglet; histopathological findings revealed multifocal ulcers and crypt abscesses with Entamoeba trophozoites and gram-negative bacilli in the piglet. These pathogens were identified as Entamoeba polecki subtype 3 and Salmonella enterica serovar Typhimurium, respectively. Numerous E. polecki subtype 3 trophozoites were located on the edge of the ulcerative and necrotic lesions in the lamina propria. Crypt abscesses were associated with S. Typhimurium. These results suggest that E. polecki subtype 3 caused multifocal ulcerative colitis accompanied by crypt abscesses with S. Typhimurium in the piglet. This study is the first report of colitis with E. polecki subtype 3 and S. Typhimurium coinfection.

Genetic identification of Entamoeba polecki subtype 3 from pigs in Japan and characterisation of its pathogenic role in ulcerative colitis

To date, three Entamoeba spp. (E. suis, zoonotic E. polecki and E. histolytica) have been identified in pigs, but their pathogenicity and molecular classification have not been fully determined. Examination and pathological analysis of pigs (n=3) with diarrhoea was conducted and revealed the presence of Entamoeba organisms. We performed a genetic analysis of the isolate using the small-subunit ribosomal RNA (SSU rRNA) gene region to identify the species. A severe ulcerative colitis was observed histopathologically with inflammatory cells, including macrophages and neutrophils, infiltrating the mucous membranes of the cecum and colon. Many Entamoeba trophozoites were found at the erosion site or at ulcerative lesions. Pathogenic viruses or bacteria were not detected. The SSU rRNA sequence of the Entamoeba isolate was found to be completely homologous to that of E. polecki subtype 3.