STEC were detected and isolated from 520 patients with diarrhea. The antibiotic drug sensitivity in vitro and ability to form biofilm were quantitatively analyzed. Shiga toxin related gene stx1 and stx2 were amplified and detected by multiplex polymerase chain reaction (PCR). The expressions of eae and ehxA genes were detected by real-time quantitative reverse transcriptase (RT)-PCR. A total of 98 isolates of Escherichia coli from fecal specimens in healthy subjects were included as control isolates.

A total of 328 isolates of Escherichia coli were isolated from patients with diarrhea. The stx1 and stx2 gene positive bacteria (STEC) had 78 isolates, accounting for 23.8%. There were 57 isolates of STEC formed biofilm (73.1%). The relative expression of eae gene was 6.57(2.82-27.8), and the expression of ehxA gene was 1.81(1.07-5.28). There were 21 isolates of STEC unformed biofilm (26.9%).The relative expression of eae gene was 3.41(0.96-12.1), and the expression of ehxA gene was 1.76(0.89-6.06). A total of 18 isolates of Vibrio parahaemolyticus were isolated, and 10 isolates were formed biofilm (55.6%). There were 3 isolates of Proteus mirabilis.Among 98 control isolates, 39 isolates were formed biofilm (39.7%). The relative expression of eae gene was 1.02(0.86-3.47), and the expression of ehxA gene was 1.03(0.88-3.03). Biofilm-formed STEC resistance to ampicillin / sulbactam, trimethoprim and ciprofloxacin was significantly higher than that of biofilm-unformed STEC and control isolates.

The STEC biofilm formation rate is significantly higher than that in healthy subjects' colonization Escherichia coli. The expression of eae gene in biofilm-formed STEC is significantly improved. The expression of ehxA gene has no significant difference with biofilm-unformed STEC.