TABLE 2.
Distribution of virulence factor-encoding genes according to the origins of the STEC isolatesa
| Genec | No. (%) of isolates of indicated originb
|
P valuee | |
|---|---|---|---|
| Dairy product or environmentd | HUS/HC patient | ||
| stx1 | 25 (62) | 4 (27) | 0.018 |
| stx2 | 20 (50) | 12 (80) | 0.045 |
| eae | 5 (12) | 8 (53) | 0.003 |
| efa1 | 5 (12) | 8 (53) | 0.003 |
| ehxA | 15 (37) | 9 (60) | NS |
| espP | 9 (22) | 8 (53) | 0.032 |
| katP | 1 (2) | 6 (40) | 0.001 |
| astA | 9 (22) | 0 | NS |
The bfp gene was absent from all strains tested.
Forty STEC strains from 1,130 dairy products or dairy environments and 15 pathogenic STEC strains were analyzed. The numbers in parentheses indicate percentages of isolates positive for the indicated genes.
The presence of the following genes was determined by PCR: stx1, stx2, eae, efa1, ehxA, katP, and astA. The presence of the following genes was determined by colony blot hybridization: ehxA, espP, and katP.
The five dairy isolates harboring the eae and efa1 genes belong to the same serogroup and share identical virulence gene patterns.
A P value of <0.05 was considered statistically significant. P values for the genes eae, efa1, espP, and katP were determined by the Fisher exact test. NS, not significant.