Interactions of clinical and environmental Aeromonas isolates with Caco-2 and HT29 intestinal epithelial cells

Aim:  Evaluation of adherence and invasion of Aeromonas spp. to human colon carcinoma cell lines Caco-2 and HT29 and assessment of cytotoxic activity. Methods and Results:  A number of 27 strains of Aeromonas caviae and 23 strains of Aeromonas hydrophila was analysed. All strains were capable to adhere to sub-confluent monolayers of Caco-2 and HT29 cell types, presenting aggregative and diffuse adherence patterns cells, respectively. In the cytotoxic assays all strains showed cytopathic and/or cytotoxic activities to Vero cells. The evaluation of the tetrazolium salt (MTT test) reduction capability was carried out in Vero, Caco-2, and HT29 cells. MTT test showed that Vero cell line was the most sensitive cell type. In the invasion test, 13 strains were analysed on Caco-2 and HT29 monolayers. Only two (15%) of the 13 strains, A. hydrophila and A. caviae species, both isolated from vegetables were invasive to Caco-2 cells. No strains were able to invade the HT29 cells. Conclusions: A. hydrophila and A. caviae isolated from human diarrhoeic faeces, vegetables, and water, were able to adhere to and produce cytotoxic/cytopathic effects in intestinal epithelial cell lines. Significance and Impact of the Study:  The presence of Aeromonas spp. in food and water samples expressing virulence factors suggest that these sources may act as dissemination vehicles of human pathogen with implication in the public health.