TABLE 2.
Phenotypic and genotypic characteristics of O157 STEC strains
| E. coli strain | Serotype | Origina | PCRb |
RT-PCRc |
Fimbria expression |
Cellulosef | Biofilm formation |
Phylogenetic groupg | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| fimH | csgA and crl | flu | cah | ehaAα | ehaAβ | Ag43 | Cah | EhaA | Curlid | T1Fe | 28°C | 37°C | 28°C | 37°C | |||||
| 581/1 | O157:H7 | C | + | + | − | + | + | + | NT | − | − | + | − | − | + | + | − | − | D |
| 691/1 | O157:H7 | C | + | + | − | − | + | + | NT | − | − | + | − | + | + | + | + | − | D |
| 1728/1 | O157:H7 | C | + | + | − | + | + | + | NT | − | − | + | − | + | + | + | + | − | D |
| 1770/1 | O157:H7 | C | + | + | − | + | + | + | NT | − | NT | − | − | − | − | − | − | − | D |
| 2004/1 | O157:H7 | C | + | + | − | + | − | + | NT | − | − | − | − | − | − | + | − | − | D |
| B1/1 | O157:H7 | C | + | + | − | + | + | + | NT | + | NT | − | − | − | − | − | − | − | D |
| B18/1 | O157:H7 | C | + | + | − | + | + | + | NT | − | NT | − | − | − | − | − | − | − | D |
| 339/02 | O157:H7 | C | + | + | + | + | + | + | − | − | − | − | − | + | − | + | − | − | D |
| 393/01 | O157:H7 | C | + | + | − | + | + | + | NT | − | NT | − | − | − | − | − | − | − | D |
| GC 148 | O157:H7 | C | + | + | − | + | + | + | NT | − | − | + | − | + | + | + | + | − | D |
| YB 20 | O157:H7 | C | + | + | − | + | + | + | NT | − | − | + | − | + | + | + | − | − | D |
| − | − | + | − | − | − | − | |||||||||||||
| 143/05 | O157:H7 | HUS | + | + | − | + | + | + | NT | − | NT | − | − | − | − | − | − | − | D |
| 337/01 | O157:H7 | BD | + | + | − | + | + | + | NT | − | NT | − | − | + | − | − | − | − | D |
| 385/01 | O157:H7 | BD | + | + | − | + | + | + | NT | − | NT | − | − | + | − | − | − | − | D |
| 156/90 | O157:H7 | D | + | + | − | + | + | + | − | − | NT | − | − | − | − | − | − | − | D |
| 255/03 | O157:H7 | BD | + | + | − | + | + | + | NT | − | NT | − | − | − | − | − | − | − | D |
| 622/03 | O157:H7 | BD | + | + | − | + | + | + | NT | − | NT | − | − | + | − | − | − | − | A |
| 102/97 | O157:H7 | W | + | + | − | + | + | + | NT | − | − | − | − | − | − | + | − | − | D |
| Total no. of strains (%) | 18 | 18 (100) | 18 (100) | 1 (6) | 17 (94) | 17 (94) | 18 (100) | 1 (6) | 5 (28) | 0 | 8 (44) | 5 (28) | 8 (44) | 3 (17) | 0 | ||||
C, cattle; D, humans with diarrhea; BD, humans with bloody diarrhea; HUS, humans with hemolytic-uremic syndrome; W, nontreated water.
No differences were observed between curli+ and curli− variants among gene sequences detected by PCR.
RT-PCR was performed only when the corresponding PCR result was positive. NT, not tested.
Detection of curli on CFA agar plates containing Congo red dye: +, red, curli-expressing colonies; −, white, non-curli-expressing colonies. Some strains presented both curli+ and curli− colonies which were purified, and the two variants were tested separately.
MSHA assay using guinea pig erythrocytes.
Cellulose production after growth on Calcofluor plates was indicated as follows: +, fluorescent colonies; −, nonfluorescent colonies.
Phylogenetic groups: A, chuA and TSPE4.C2 negative; D, chuA+ and yjaA negative.