Prevalence of noncanonical virulence factors in the adherence and invasion by enterotoxigenic Escherichia coli in the small and large intestines
Abstract
Introduction: Enterotoxigenic Escherichia coli (ETEC) expresses a diverse set of noncanonical genes that increase its virulence and are involved in mucin degradation, epithelial invasion, and biofilm formation. Collectively, these factors enable effective intestinal colonization, leading to watery diarrhea.
Aim: This study investigated the prevalence of the noncanonical genes tia, tibA, and leoA and their effects on the ability of ETEC to adhere, invade, and form biofilms.
Materials and methods: A total of 244 ETEC strains were analyzed by PCR to confirm the presence of noncanonical virulence genes (tia, tibA, and leoA) and toxins, including heat-labile toxins (LTs) and/or heat-stable toxins (STs). The ability of the strains to adhere to and invade HT-29 colorectal adenocarcinoma cells (large intestine) and HuTu80 duodenal adenocarcinoma cells (small intestine) was evaluated, along with their ability to form biofilms. The susceptibility of these strains to 18 antibiotics was evaluated in accordance with the Clinical & Laboratory Standards Institute (CLSI) 2025 guidelines.
Results: Our data revealed that the tia, tibA and leoA genes were amplified in 11.34% (11/97), 15.46% (15/97), and 7.21% (7/97) of the ETEC strains, respectively. ETEC tia+ strains showed adherence values ranging from 3.6 × 105 to 34.1 × 105 CFUs/mL in HT-29 cells and from 4.1 × 105 to 16.6 × 105 CFUs/mL in HuTu80 cells. ETEC tibA + strains exhibited adherence values ranging from 11.16 × 105 to 65.1 × 105…
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