Characterization of a Novel Diarrheagenic Strain of Associated With Food Poisoning in China.

is commonly considered to be an opportunistic pathogen causing urinary tract infections (UTIs) in humans. However, some strains of were found to be associated with food poisoning outbreaks, with the pathogenic mechanism still unclear. In our study, we described a novel strain of C02011 isolated from patients' specimens in a food poisoning in China. In order to determine its gastrointestinal pathogenicity, experiments were performed to compare B02005 strain (isolated from healthy people) and American Type Culture Collection (ATCC) 29906 strain both [Caco-2 cells: bacterial adhesion and invasion assays, Giemsa staining, and transmission electron microscopy (TEM)] and [BALB/c mouse model: fecal character, colon injury, histological examination, immunochemistry, and western blotting (WB)]. According to the results, C02011 strain exhibited almost identical characteristics with B02005 strain in bacterial appearance and proliferation. , Caco-2 cells were infected with C02011, B02005, and ATCC 29906 strains. After that, Giemsa staining and TEM were used for observing the infection process of C02011 strain. Meanwhile, the adhesive abilities of different strains were rated as follows: B02005 > C02011 > ATCC 29906 ( < 0.01). Invasive abilities of different strains were rated as follows: C02011 > B02005 > ATCC 29906 ( < 0.01). , BALB/c mice were infected with C02011 and B02005 strains. C02011 strain shows more virulence than B02005 strain in terms of the following indicators: (1) feces water content and fecal character; (2) colon length of mice; (3) histological examination on mouse intestine tissues; (4) ELISA for detecting TNF-α level in the colon; and (5) WB and immunohistochemistry (IHC) for detecting occludin protein expression in the colon. On the basis of these results, we firstly validated that the novel strain of C02011 shows more gastrointestinal pathogenicity than the other strains isolated from a healthy individual. In addition, type IV secretion system (T4SS) was preliminarily confirmed to play an important role in the pathogenesis of diarrheal isolated from the food poisoning incident.