Adhesion and cytotoxicity of Aeromonas caviae to rabbit intestinal epithelium ex vivo.

UNLABELLED: Aeromonads are considered potential pathogens for humans and animals and are responsible for the etiology of intestinal and extraintestinal diseases. The presence of Aeromonas spp. in food and water shows that it is an important vehicle of infection in humans. The pathology caused by these bacteria involves several virulence factors, such as the ability to produce toxins, adhesion and invasion. The present study investigated the interaction of five Aeromonas caviae strains isolated from human diarrheic faeces with rabbit ileal and colonic mucosa ex vivo, using in vitro organ culture model. The in vitro adhesion assays using cultured tissue were performed with A. caviae strains co-incubated with intestinal fragments of ileum and colon over a period of 6 h. The fragments were analyzed by light and electron microscopy. All strains adhered to rabbit ileal and colonic mucosa ex vivo, with higher degree of adherence presented on colonic mucosa. The typical aggregative adherence pattern was observed among strains studied. Through electron and light microscopy, we observed extensive colonization of ileal and colonic mucosa, large mucus production, biofilm formation and morphological alterations such as intense vacuolization, structural disorganization, cell extrusion and destruction of the villi. These results demonstrate that in vitro organ culture of intestinal mucosa from rabbit may be used to investigate Aeromonas spp. PATHOGENESIS: Finally, our results support the pathogenic potential of Aeromonas emphasising their importance in public health.

Adhesion, invasion, intracellular survival and cytotoxic activity of strains of Aeromonas spp. in HEp-2, Caco-2 and T-84 cell lines.

The genus Aeromonas contains important pathogen for both humans and other animals, being responsible for the etiology of intestinal and extraintestinal diseases. The pathology caused by these bacteria involves several virulence factors, such as the ability to produce toxins, adhesion and invasion. The properties conferred by these factors have been extensively studied in experiments of interaction between bacterial strains and cell culture. We evaluate the interaction of eight Aeromonas spp. strains, previously isolated from human faeces, food and water with HEp-2, Caco-2 and T-84 cell lines. Cytotoxic effects, the pattern of adhesion, invasive capacity and intracellular survival were analyzed. The results showed that Aeromonas strains were adherent to three cells lines in 6 h of incubation, displaying the aggregative adherence pattern. Among eight strains studied, 50% produced cytotoxic effects on HEp-2 cells, while none of the strains produced cytotoxic effects on Caco-2 and T-84 cells at 48 h. This study demonstrated that subsets of Aeromonas isolated from different sources were able to invade intestinal (T-84, Caco-2) and epithelial (HEp-2) cell lines cultivated in vitro surviving in intracellular environments up to 72 h. Finally, our results support the pathogenic potential of Aeromonas, especially those of food and clinical sources.