Early Epithelial Invasion by Salmonella enterica Serovar Typhimurium DT104 in the Swine Ileum

• Published in: Veterinary pathology Vol. 39; no. 6; pp. 712 - 720
• Main Authors: Meyerholz, D. K., Stabel, T. J., Ackermann, M. R., Carlson, S. A., Jones, B. D., Pohlenz, J.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.11.2002
• Subjects: Animals; Ileum - microbiology; Ileum - pathology; Ileum - ultrastructure; In Vitro Techniques; Intestinal Diseases - microbiology; Intestinal Diseases - pathology; Intestinal Diseases - veterinary; Intestinal Mucosa - microbiology; Intestinal Mucosa - pathology; Intestinal Mucosa - ultrastructure; Microscopy, Electron, Scanning - veterinary; Random Allocation; Salmonella Infections, Animal - microbiology; Salmonella Infections, Animal - pathology; Salmonella typhimurium - growth & development; Swine; Swine Diseases - microbiology; Swine Diseases - pathology; DT104; ileum; swine; Salmonella; Typhimurium; invasion; extrusion; electron microscopy; enterocyte
• ISSN: 0300-9858; 1544-2217
• DOI: 10.1354/vp.39-6-712

Salmonella enterica serovar Typhimurium is an important intestinal pathogen in swine. This study was performed to document the early cellular invasion of Salmonella serovar Typhimurium in swine ileum. Ileal gut-loops were surgically prepared in ten 4- to 5-week-old mixed-breed pigs and inoculated for 0-60 minutes. Loops were harvested and prepared for both scanning and transmission electron microscopy (SEM and TEM, respectively). Preferential bacterial adherence to microfold cells (M cells) was seen within 5 minutes, and by 10 minutes bacterial invasion of the apical membrane was seen in M cells, goblet cells, and enterocytes. This multicellular invasion was observed throughout the course of infection. In addition, SEM revealed a specific affinity of Salmonella serovar Typhimurium to sites of cell extrusion. Using TEM, bacteria in these areas were focused in the crevices formed by the extruding cell and the adjacent cells and in the cytoplasm immediately beneath the extruding cell. Our results suggest that early cellular invasion by Salmonella serovar Typhimurium is nonspecific and rapid in swine. Furthermore, the combination of SEM and TEM data suggests that Salmonella serovar Typhimurium may use sites of cell extrusion as an additional mechanism for early invasion.