A total of 381 Escherichia coli strains were isolated from 264 fecal samples of the diarrheic and healthy nursing piglets and post-weaning piglets. PCR technique was used to detect the enterotoxin producing genes (It-I, sta, stb and ast), Shiga toxin producing genes (stx1, stx2, stx2e), adherent genes (eae, F4 and F18) of E. coli. The studied results showed that in 84 E. coli strains isolated from fecal samples of the healthy piglets, there were 7/10 virulent genes including stx1, stx2, eae, It-I, sta, ast and F18 genes with the rates of 7.2 percent, 1.2 percent,2.4 percent, 1.2 percent, 10.4 percent,35.7 percent and 2.4 percent respectively identified. The rate of isolated E. coli strains carrying at least one gene was 53.6 percent (45/84)
Of which, there were 7 E. coli strains possessing two genes, 38 strains carried only one gene. Whereas, from 50 E. coli strains isolated from the healthy post-weaning piglets, there were only 4 genes: astA, stx2, sta and F18 with the rates of 28 percent, 8 percent, 2 percent and 2 percent respectively identified. From a total of 50 E. coli strains passed through PCR test, there were 18 (36 percent) strains carrying virulent genes
Of which, 17 strains carried one gene and 1 strain carried three genes (F18, stx2 and sta) identified. Meanwhile, from 94 E. coli strains isolated from fecal samples of the diarrheic nursing piglets, there were 56 strains (59.6 percent) carrying at least one gene detected
Of which, 9 strains possessed two genes, 3 strains possessed three genes, 1 strains possessed four genes (It-I, ast, stb and F4) and 43 strains possessed only one gene. Similarly, from 153 E. coli strains isolated from diarrhea/oedema post-weaning piglets, there were 99 strains (54.9 percent) carrying at least one gene detected
Of which, 70 strains possessed only one gene, 25 strains possessed two genes, 2 strains possessed three genes, 1 strain possessed four genes (stx2, sta, stx2e and F18), 1 strain possessed five genes (stx2e, ast, sta, It-I and F18). In summary, the rate of genes producing Shiga toxins of E. coli isolated from fecal samples of the post-weaning piglets was higher than that of E. coli isolated from fecal samples of the healthy or diarrheic piglets. By contrast, the rate of sta gene in fecal samples of the nursing piglets was higher than that of the post-weaning piglets or in the same age group, the rate of this gene in the diarrheic piglets was higher than that of the healthy piglets. There was not significant difference of ast gene presenting in fecal samples of the healthy and diarrheic nursing piglets or post-weaning piglets and ast gene accounted for the highest rate among 10 virulent genes. Identified frequency of eae, F4 (4 strains) and F18 (11 strains) genes was relatively low.